Method for seamlessly changing power modes in a ADSL system

• US 6,567,473 B1
• Filed: 03/10/2000
• Issued: 05/20/2003
• Est. Priority Date: 03/12/1999
• Status: Expired due to Term

• Current Assignee: Intellectual Ventures II LLC (Intellectual Ventures LLC)
• Original Assignee: Aware Incorporated (Crowley Holdings Preferred LLC)
• Inventors: Tzannes, Marcos
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Lugo, David B.
• Application Number:
  US09/522,870
• Time in Patent Office: 1,166 Days
• Field of Search: 375/260, 375/222, 375/349, 375/259, 375/261, 375/219, 370/465, 370/466, 370/538
• US Class Current: 375/260
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0016 involving special memory structures, e.g. look-up tables
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/004 by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/0075 Transmission of coding parameters to receiver H04L1/0023 takes precedence
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/18 End to end
• CPC Class Codes: H04L 47/263 Rate modification at the source after receiving feedback
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0046 Determination of how many bits are transmitted on different sub-channels
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0064 Rate requirement of the data, e.g. scalable bandwidth, data priority
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated
• CPC Class Codes: H04L 5/1446 of transmission speed
• CPC Class Codes: H04M 11/062 : using different frequency bands for speech and other data
• CPC Class Codes: Y02D 30/50 : in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

A DMT system and method with the capability to adapt the system bit rate on-line in a seamless manner. The DMT system provides a robust and fast protocol for completing this seamless rate adaptation. The DMT system also provides a framing and encoding method with reduced overhead compared to conventional DMT systems. The DMT system and method provide seamless rate adaptation with the provision of different power levels. This framing and encoding method enables a system with seamless rate adaptation capability. The system and method of the invention can be implemented in hardware, or alternatively in a combination of hardware and software.

Claims

1. In a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, a method for seamlessly entering a second power mode, the method comprising:

storing a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the transmitter and receiver;

seamlessly transitioning to the second power mode based on the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode also being used to transmit and receive codewords in the second power mode; and

transmitting and receiving codewords using the second bit allocation table.

2. The method of claim 1 wherein the synchronizing includes sending a flag signal.

3. The method of claim 2 wherein the flag signal is a predefined signal.

4. The method of claim 3 wherein the predefined signal is a sync symbol with a predefined phase shift.

5. The method of claim 3 wherein the predefined signal is an inverted sync symbol.

6. The method of claim 2 wherein the transmitter transmits the flag signal to the receiver.

7. The method of claim 2 wherein the receiver transmits the flag signal to the transmitter.

8. The method of claim 1 wherein the second power mode is a low power mode.

9. The method of claim 8 further comprising allocating zero bits to carrier signals to achieve a transmission bit rate of approximately zero kilobits per second in the low power mode.

10. The method of claim 8 further comprising transmitting a pilot tone for timing recovery when operating in the low power mode.

11. The method of claim 8 further comprising periodically transmitting a sync symbol when operating in the low power mode.

12. The method of claim 2 further comprising using the first bit allocation table for transmitting a plurality of DMT symbols in the first power mode and switching to the second bit allocation table for transmitting the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for transmission starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal.

13. The method of claim 12 wherein the predetermined DMT symbol is the first DMT symbol that follows the transmission of the flag signal.

14. The method of claim 1 wherein the second power mode is a full power mode.

15. The method of claim 1 wherein the first power mode is a full power mode, and the second power mode is a low power mode.

16. The method of claim 1 wherein the first power mode is a low power mode, and the second power mode is a full power mode.

17. The method of claim 2, further comprising using the first bit allocation table for receiving a plurality of DMT symbols in the first power mode and switching to the second bit allocation table for receiving the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for receiving starting with a predetermined one of the DMT symbols that follows the reception of the flag signal.

18. The method of claim 12, wherein the predetermined DMT symbol is a first DMT symbol that follows the reception of the flag signal.

19. The method of claim 1, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

20. The method of claim 2, wherein the flag signal comprises at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

21. The method of claim 1, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

22. In a multicarrier transmitter operating in a low power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, a method for exiting the low power mode and entering a full power mode, the method comprising:

storing a second bit allocation table for modulating bits on to subchannels to be used for transmission at a second increased data rate during the full power mode;

synchronizing use of the second bit allocation table between the transmitter and a receiver by transmitting a flag signal; and

seamlessly entering the full power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

23. The method of claim 22, wherein the predetermined DMT symbol is a first DMT symbol that follows the transmission of the flag signal.

24. The method of claim 22, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

25. The method of claim 22, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

26. The method of claim 22, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

27. In a multicarrier receiver operating in a low power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, a method for exiting the low power mode and entering a full power mode, the method comprising:

storing a second bit allocation table for demodulating bits from subchannels to be used for reception at a second increased data rate during the full power mode;

synchronizing use of the second bit allocation table between the receiver and a transmitter by receiving a flag signal; and

seamlessly entering the full power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

28. The method of claim 27, wherein the predetermined DMT symbol is the first DMT symbol that follows the reception of the flag signal.

29. The method of claim 27, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

30. The method of claim 27, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

31. The method of claim 27, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

32. In a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, a method for entering a low power mode, the method comprising:

receiving from a second transceiver a message comprising at least one parameter of a second bit allocation table for modulating bits on to at least one subchannel to be used for transmitting at a second reduced data rate during the low power mode;

synchronizing use of the second bit allocation table between the transceiver and the second transceiver by transmitting a flag signal; and

seamlessly entering the low power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols, and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

33. The method of claim 32, wherein the predetermined DMT symbol is a first DMT symbol that follows the transmission of the flag signal.

34. The method of claim 32, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

35. The method of claim 32, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

36. The method of claim 32, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

37. In a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, a method for entering a low power mode, the method comprising:

transmitting to a second transceiver a message comprising at least one parameter of a second bit allocation table for demodulating bits from at least one subchannel to be used for receiving at a second reduced data rate during the low power mode;

synchronizing use of the second bit allocation table between the transceiver and the second transceiver by receiving a flag signal; and

seamlessly entering the low power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols, and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

38. The method of claim 37, wherein the predetermined DMT symbol is a first DMT symbol that follows the reception of the flag signal.

39. The method of claim 37, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

40. The method of claim 37, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

41. The method of claim 37, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

42. In a multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, a method for seamlessly entering a second power mode, the method comprising:

storing a second bit allocation table to be used for transmitting codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the transmitter and a receiver;

seamlessly transitioning to the second power mode based on the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit codewords in the first power mode also being used to transmit codewords in the second power mode; and

transmitting codewords using the second bit allocation table.

43. The method of claim 42, wherein synchronizing includes sending a flag signal.

44. The method of claim 43, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

45. The method of claim 43, wherein at least one of the transmitter transmits the flag signal to the receiver and the receiver transmits the flag signal to the transmitter.

46. The method of claim 42, wherein the second power mode is a low power mode.

47. The method of claim 46, further comprising allocating zero bits to one or more carrier signals to achieve a transmission bit rate of approximately zero kilobits per second in the low power mode.

48. The method of claim 46, further comprising transmitting a pilot tone for timing recovery when operating in the low power mode.

49. The method of claim 46, further comprising periodically transmitting a sync symbol when operating in the low power mode.

50. The method of claim 43, further comprising using the first bit allocation table for transmitting a plurality of DMT symbols in the first power mode and switching to the second bit allocation table for transmitting the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for transmission starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal.

51. The method of claim 50, wherein the predetermined DMT symbol is a first DMT symbol that follows the transmission of the flag signal.

52. The method of claim 42, wherein the second power mode is a full power mode.

53. The method of claim 42, wherein the first power mode is a full power mode, and the second power mode is a low power mode.

54. The method of claim 42, wherein the first power mode is a low power mode, and the second power mode is a full power mode.

55. The method of claim 42, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

56. The method of claim 42, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

57. In a multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, a method for seamlessly entering a second power mode, the method comprising:

storing a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the receiver and a transmitter;

seamlessly transitioning to the second power mode based on the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to receive codewords in the first power mode also being used to receive codewords in the second power mode; and

receiving codewords using the second bit allocation table.

58. The method of claim 57, wherein the synchronizing includes receiving a flag signal.

59. The method of claim 58, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

60. The method of claim 58, wherein at least one of the transmitter transmits the flag signal to the receiver and the receiver transmits the flag signal to the transmitter.

61. The method of claim 57, wherein the second power mode is a low power mode.

62. The method of claim 61, further comprising allocating zero bits to carrier signals to achieve a bit rate of approximately zero kilobits per second in the low power mode.

63. The method of claim 61, further comprising receiving a pilot tone for timing recovery when operating in the low power mode.

64. The method of claim 61, further comprising periodically receiving a sync symbol when operating in the low power mode.

65. The method of claim 58, further comprising using the first bit allocation table for receiving a plurality of DMT symbols in the first power mode and switching to the second bit allocation table for receiving the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for receiving starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal.

66. The method of claim 65, wherein the predetermined DMT symbol is a first DMT symbol that follows the transmission of the flag signal.

67. The method of claim 57, wherein the second power mode is a full power mode.

68. The method of claim 57, wherein the first power mode is a full power mode, and the second power mode is a low power mode.

69. The method of claim 57, wherein the first power mode is a low power mode, and the second power mode is a full power mode.

70. The method of claim 57, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

71. The method of claim 57, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

72. An information storage media comprising information for a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, instructions on the media operable to seamlessly enter a second power mode comprising:

information that stores a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode;

information that synchronizes use of the second bit allocation table between the transmitter and receiver;

information that seamlessly transitions to the second power mode based on the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode also being used to transmit and receive codewords in the second power mode; and

information that transmits and receives codewords using the second bit allocation table.

73. The media of claim 72, wherein the synchronizing includes sending a flag signal.

74. The media of claim 73, wherein the flag signal comprises at least one of a predefined signal, a sync symbol with a predefined phase shift, an inverted sync symbol and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

75. The media of claim 73, wherein the transmitter transmits the flag signal to the receiver.

76. The media of claim 73, wherein the receiver transmits the flag signal to the transmitter.

77. The media of claim 73, wherein the second power mode is a low power mode.

78. The media of claim 77, further comprising information that allocates zero bits to one or more carrier signals to achieve a transmission bit rate of approximately zero kilobits per second in the low power mode.

79. The media of claim 77, further comprising information that transmits a pilot tone for timing recovery when operating in the low power mode.

80. The media of claim 77, further comprising information that periodically transmits a sync symbol when operating in the low power mode.

81. The media of claim 73, further comprising information that uses the first bit allocation table to transmit a plurality of DMT symbols in the first power mode and to switch to the second bit allocation table to transmit the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for transmission starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal.

82. The media of claim 81, wherein the predetermined DMT symbol is the first DMT symbol that follows the transmission of the flag signal.

83. The media of claim 72, wherein the second power mode is a full power mode.

84. The media of claim 72, wherein the first power mode is a full power mode, and the second power mode is a low power mode.

85. The media of claim 72, wherein the first power mode is a low power mode, and the second power mode is a full power mode.

86. The media of claim 73, further comprising information that uses the first bit allocation table to receive a plurality of DMT symbols in the first power mode and to switch to the second bit allocation table to receive the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for receiving starting with a predetermined one of the DMT symbols that follows the reception of the flag signal.

87. The media of claim 81, wherein the predetermined DMT symbol is a first DMT symbol that follows the reception of the flag signal.

88. The media of claim 72, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

89. The media of claim 72, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

90. In a multicarrier transmitter operating in a low power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, an information storage media including information operable to exit the low power mode and to enter a full power mode comprising:

information that stores a second bit allocation table to modulate bits on to subchannels to be used for transmission at a second increased data rate during the full power mode;

information that synchronizes use of the second bit allocation table between the transmitter and a receiver by transmitting a flag signal; and

information that is operable to seamlessly enter the full power mode by using the second bit allocation table to modulate bits on to subchannels to generate the plurality of DMT symbols and to transmit at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

91. The media of claim 90, wherein the predetermined DMT symbol is a first DMT symbol that follows the transmission of the flag signal.

92. The media of claim 91, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

93. The media of claim 90, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

94. The media of claim 90, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

95. In a multicarrier receiver operating in a low power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, an information storage media including information to exit the low power mode and to enter a full power mode comprising:

information that stores a second bit allocation table to demodulate bits from subchannels to be used for reception at a second increased data rate during the full power mode;

information that synchronizes use of the second bit allocation table between the receiver and a transmitter by receiving a flag signal; and

information that is operable to seamlessly enter the full power mode by using the second bit allocation table to demodulate bits from subchannels in the plurality of DMT symbols and to receive at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

96. The media of claim 95, wherein the predetermined DMT symbol is the first DMT symbol that follows the reception of the flag signal.

97. The media of claim 95, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

98. The media of claim 95, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

99. The media of claim 95, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

100. In a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, an information storage media including information operable to enter a low power mode comprising:

information that receives from a second transceiver a message comprising at least one parameter of a second bit allocation table for modulating bits on to at least one subchannel to be used for transmitting at a second reduced data rate during the low power mode;

information that synchronizes use of the second bit allocation table between the transceiver and the second transceiver by transmitting a flag signal; and

information that is operable to seamlessly enter the low power mode by using the second bit allocation table to modulate bits on to subchannels to generate the plurality of DMT symbols, and to transmit at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

101. The media of claim 100, wherein the predetermined DMT symbol is a first DMT symbol that follows the transmission of the flag signal.

102. The media of claim 100, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

103. The media of claim 100, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

104. The media of claim 100, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

105. In a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, an information storage media including information to enter a low power mode comprising:

information that transmits to a second transceiver a message comprising at least one parameter of a second bit allocation table for demodulating bits from at least one subchannel to be used for receiving at a second reduced data rate during the low power mode;

information that synchronizes use of the second bit allocation table between the transceiver and the second transceiver by receiving a flag signal; and

information that is operable to seamlessly enter the low power mode by using the second bit allocation table to demodulate bits from subchannels in the plurality of DMT symbols, and to receive at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

106. The media of claim 105, wherein the predetermined DMT symbol is a first DMT symbol that follows the reception of the flag signal.

107. The media of claim 105, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

108. The media of claim 105, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

109. The media of claim 105, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

110. In a multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, an information storage media including information to seamlessly entering a second power mode comprising:

information that stores a second bit allocation table to be used for transmitting codewords at a second bit rate in the second power mode;

information that synchronizes use of the second bit allocation table between the transmitter and a receiver;

information operable to seamlessly transition to the second power mode based on the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit codewords in the first power mode also being used to transmit codewords in the second power mode; and

information that transmits codewords using the second bit allocation table.

111. The media of claim 110, wherein synchronizing includes sending a flag signal.

112. The media of claim 111, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

113. The media of claim 111, wherein at least one of the transmitter transmits the flag signal to the receiver and the receiver transmits the flag signal to the transmitter.

114. The media of claim 110, wherein the second power mode is a low power mode.

115. The media of claim 114, further comprising information that allocates zero bits to one or more carrier signals to achieve a transmission bit rate of approximately zero kilobits per second in the low power mode.

116. The media of claim 114, further comprising information that transmits a pilot tone for timing recovery when operating in the low power mode.

117. The media of claim 114, further comprising information that periodically transmits a sync symbol when operating in the low power mode.

118. The media of claim 114, further comprising information that uses the first bit allocation table for transmitting a plurality of DMT symbols in the first power mode and switching to the second bit allocation table for transmitting the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for transmission starting with a predetermined one of the DMT symbols that follows the transmission of a flag signal.

119. The media of claim 118, wherein the predetermined DMT symbol is a first DMT symbol that follows the transmission of the flag signal.

120. The media of claim 110, wherein the second power mode is a full power mode.

121. The media of claim 110, wherein the first power mode is a full power mode, and the second power mode is a low power mode.

122. The media of claim 110, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

123. The media of claim 110, wherein the first power mode is a low power mode, and the second power mode is a full power mode.

124. The media of claim 110, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

125. In a multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, an information storage media including information operable to seamlessly enter a second power mode comprising:

information that stores a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode;

information that synchronizes use of the second bit allocation table between the receiver and a transmitter;

information operable to seamlessly transition to the second power mode based on the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to receive codewords in the first power mode also being used to receive codewords in the second power mode; and

information that receives codewords using the second bit allocation table.

126. The media of claim 125, wherein the synchronizing includes information that receives a flag signal.

127. The media of claim 126, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

128. The media of claim 126, wherein at least one of the transmitter transmits the flag signal to the receiver and the receiver transmits the flag signal to the transmitter.

129. The media of claim 125, wherein the second power mode is a low power mode.

130. The media of claim 129, further comprising information that allocates zero bits to carrier signals to achieve a bit rate of approximately zero kilobits per second in the low power mode.

131. The media of claim 129, further comprising information that receives a pilot tone for timing recovery when operating in the low power mode.

132. The media of claim 129, further comprising information that periodically receives a sync symbol when operating in the low power mode.

133. The media of claim 125, further comprising information that uses the first bit allocation table for receiving a plurality of DMT symbols in the first power mode and switching to the second bit allocation table for receiving the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for receiving starting with a predetermined one of the DMT symbols that follows the receiving of a flag signal.

134. The media of claim 133, wherein the predetermined DMT symbol is a first DMT symbol that follows the receiving of the flag signal.

135. The media of claim 125, wherein the second power mode is a full power mode.

136. The media of claim 125, wherein the first power mode is a full power mode, and the second power mode is a low power mode.

137. The media of claim 125, wherein the first power mode is a low power mode, and the second power mode is a full power mode.

138. The media of claim 125, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel, and the fine gain values for at least one subchannel.

139. The media of claim 125, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

140. A multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the system operable to seamlessly enter a second power mode comprising:

a plurality of memory devices that store a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode; and

a flag signal that synchronizes use of the second bit allocation table between the transmitter and receiver, the multicarrier communication system seamlessly transitioning to the second power mode based on the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode also being used to transmit and receive codewords in the second power mode and transmitting and receiving codewords using the second bit allocation table.

141. The system of claim 140, wherein the flag signal comprises at least one of a predefined signal, a sync symbol with a predefined phase shift, an inverted sync symbol and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

142. The system of claim 141, wherein the transmitter transmits the flag signal to the receiver.

143. The system of claim 141, wherein the receiver transmits the flag signal to the transmitter.

144. The system of claim 140, wherein the second power mode is a low power mode.

145. The system of claim 144, further comprising at least one of the transmitter and the receiver allocating zero bits to one or more carrier signals to achieve a transmission bit rate of approximately zero kilobits per second in the low power mode.

146. The system of claim 144, further comprising at least one of the transmitter and receiver transmitting a pilot tone for timing recovery when operating in the low power mode.

147. The system of claim 144, further comprising at least one of the transmitter and receiver periodically transmitting a sync symbol when operating in the low power mode.

148. The system of claim 141, wherein transmitter uses the first bit allocation table for transmitting a plurality of DMT symbols in the first power mode and switches to the second bit allocation table for transmitting the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for transmission starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal.

149. The system of claim 148, wherein the predetermined DMT symbol is the first DMT symbol that follows the transmission of the flag signal.

150. The system of claim 140, wherein the second power mode is a full power mode.

151. The system of claim 140, wherein the first power mode is a full power mode, and the second power mode is a low power mode.

152. The system of claim 140, wherein the first power mode is a low power mode, and the second power mode is a full power mode.

153. The system of claim 141, wherein the receiver uses the first bit allocation table for receiving a plurality of DMT symbols in the first power mode and switches to the second bit allocation table for receiving the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for receiving starting with a predetermined one of the DMT symbols that follows the reception of the flag signal.

154. The system of claim 153, wherein the predetermined DMT symbol is a first DMT symbol that follows the reception of the flag signal.

155. The system of claim 140, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

156. The system of claim 140, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

157. A multicarrier transmitter operating in a low power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the transmitter exiting the low power mode and entering a full power mode comprising:

a memory that stores a second bit allocation table for modulating bits on to subchannels to be used for transmission at a second increased data rate during the full power mode;

a flag signal that synchronizes use of the second bit allocation table between the transmitter and a receiver, wherein the transmitter seamlessly enters the full power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmits at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

158. The system of claim 157, wherein the predetermined DMT symbol is a first DMT symbol that follows the transmission of the flag signal.

159. The system of claim 157, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

160. The system of claim 157, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

161. The system of claim 157, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

162. A multicarrier receiver operating in a low power mode at a first data rate using a first bit allocation table to demodulating bits from subchannels in a plurality of DMT symbols, the receiver exiting the low power mode and entering a full power mode comprising:

a memory that stores a second bit allocation table for demodulating bits from subchannels to be used for reception at a second increased data rate during the full power mode; and

a flag signal that synchronizes use of the second bit allocation table between the receiver and a transmitter, wherein the receiver seamlessly enters the full power mode by using the second bit allocation table to demodulate bits from subchannels in the plurality of DMT symbols and receives at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

163. The system of claim 162, wherein the predetermined DMT symbol is the first DMT symbol that follows the reception of the flag signal.

164. The system of claim 162, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

165. The system of claim 162, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

166. The system of claim 162, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

167. A multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the transmitter entering a low power mode comprising:

a message received from a second transceiver comprising at least one parameter of a second bit allocation table for modulating bits on to at least one subchannel to be used for transmitting at a second reduced data rate during the low power mode; and

a flag signal that synchronizes use of the second bit allocation table between the transceiver and the second transceiver, wherein the transceiver seamlessly enters the low power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols, and transmits at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

168. The system of claim 167, wherein the predetermined DMT symbol is a first DMT symbol that follows the transmission of the flag signal.

169. The system of claim 167, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

170. The system of claim 167, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

171. The system of claim 167, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

172. A multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, the receiver entering a low power mode comprising:

a message transmitted to a second transceiver comprising at least one parameter of a second bit allocation table for demodulating bits from at least one subchannel to be used for receiving at a second reduced data rate during the low power mode;

a flag signal that synchronizes use of the second bit allocation table between the transceiver and the second transceiver, wherein the transceiver seamlessly enters the low power mode by using the second bit allocation table to demodulating bits from subchannels in the plurality of DMT symbols, and receives at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

173. The system of claim 172, wherein the predetermined DMT symbol is a first DMT symbol that follows the reception of the flag signal.

174. The system of claim 172, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

175. The system of claim 172, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

176. The system of claim 172, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

177. A multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the system seamlessly entering a second power mode comprising:

a plurality of memory devices that store a second bit allocation table to be used for transmitting codewords at a second bit rate in the second power mode; and

a flag signal that synchronizes use of the second bit allocation table between the transmitter and a receiver wherein the transmitter seamlessly transitions to the second power mode based on the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit codewords in the first power mode also being used to transmit codewords in the second power mode and transmits codewords using the second bit allocation table.

178. The system of claim 177, wherein synchronizing includes sending the flag signal to at least one of the transmitter and receiver.

179. The system of claim 177, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

180. The system of claim 178, wherein at least one of the transmitter transmits the flag signal to the receiver and the receiver transmits the flag signal to the transmitter.

181. The system of claim 177, wherein the second power mode is a low power mode.

182. The system of claim 181, wherein the transmitter allocates zero bits to one or more carrier signals to achieve a transmission bit rate of approximately zero kilobits per second in the low power mode.

183. The system of claim 181, wherein the transmitter transmits a pilot tone for timing recovery when operating in the low power mode.

184. The system of claim 181, wherein the transmitter periodically transmitting a sync symbol when operating in the low power mode.

185. The system of claim 178, wherein the transmitter uses the first bit allocation table for transmitting a plurality of DMT symbols in the first power mode and switches to the second bit allocation table for transmitting the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for transmission starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal.

186. The system of claim 185, wherein the predetermined DMT symbol is a first DMT symbol that follows the transmission of the flag signal.

187. The system of claim 177, wherein the second power mode is a full power mode.

188. The system of claim 177, wherein the first power mode is a full power mode, and the second power mode is a low power mode.

189. The system of claim 177, wherein the first power mode is a low power mode, and the second power mode is a full power mode.

190. The system of claim 177, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

191. The system of claim 177, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

192. A multicarrier communication system receiver using a first sit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the receiver seamlessly entering a second power mode comprising:

a memory that stores a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode; and

a flag signal that synchronizes use of the second bit allocation table between the receiver and a transmitter, wherein the receiver seamlessly transitions to the second power mode based on the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to receive codewords in the first power mode also being used to receive codewords in the second power mode and receives codewords using the second bit allocation table.

193. The system of claim 192, wherein the synchronizing includes receiving the flag signal at at least one of the transmitter and receiver.

194. The system of claim 193, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

195. The system of claim 193, wherein at least one of the transmitter transmits the flag signal to the receiver and the receiver transmits the flag signal to the transmitter.

196. The system of claim 192, wherein the second power mode is a low power mode.

197. The system of claim 196, wherein the receiver allocates zero bits to carrier signals to achieve a bit rate of approximately zero kilobits per second in the low power mode.

198. The system of claim 196, wherein the receiver receives a pilot tone for timing recovery when operating in the low power mode.

199. The system of claim 196, wherein the receiver periodically receiving a sync symbol when operating in the low power mode.

200. The system of claim 192, wherein the receiver uses the first bit allocation table for receiving a plurality of DMT symbols in the first power mode and switching to the second bit allocation table for receiving the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for receiving starting with a predetermined one of the DMT symbols that follows the receiving of the flag signal.

201. The system of claim 200, wherein the predetermined DMT symbol is a first DMT symbol that follows the receiving of the flag signal.

202. The system of claim 192, wherein the second power mode is a full power mode.

203. The system of claim 192, wherein the first power mode is a full power mode, and the second power mode is a low power mode.

204. The system of claim 192, wherein the first power mode is a low power mode, and the second power mode is a full power mode.

205. The system of claim 192, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

206. The system of claim 192, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

207. A communications protocol for a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the protocol operable to seamlessly enter a second power mode comprising:

storing a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the transmitter and receiver;

seamlessly transitioning to the second power mode based on the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode also being used to transmit and receive codewords in the second power mode; and

transmitting and receiving codewords using the second bit allocation table.

208. The protocol of claim 207, wherein the synchronizing includes sending the flag signal.

209. The protocol of claim 208, wherein the flag signal comprises at least one of a predefined signal, a sync symbol with a predefined phase shift, an inverted sync symbol and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

210. The protocol of claim 208, wherein the transmitter transmits the flag signal to the receiver.

211. The protocol of claim 208, wherein the receiver transmits the flag signal to the transmitter.

212. The protocol of claim 207, wherein the second power mode is a low power mode.

213. The protocol of claim 212, further comprising allocating zero bits to one or more carrier signals to achieve a transmission bit rate of approximately zero kilobits per second in the low power mode.

214. The protocol of claim 212, further comprising transmitting a pilot tone for timing recovery when operating in the low power mode.

215. The protocol of claim 212, further comprising periodically transmitting a sync symbol when operating in the low power mode.

216. The protocol of claim 208, further comprising using the first bit allocation table to transmit a plurality of DMT symbols in the first power mode and to switch to the second bit allocation table to transmit the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for transmission starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal.

217. The protocol of claim 216, wherein the predetermined DMT symbol is the first DMT symbol that follows the transmission of the flag signal.

218. The protocol of claim 207, wherein the second power mode is a full power mode.

219. The protocol of claim 207, wherein the first power mode is a full power mode, and the second power mode is a low power mode.

220. The protocol of claim 207, wherein the first power mode is a low power mode, and the second power mode is a full power mode.

221. The protocol of claim 208, further comprising using the first bit allocation table to receive a plurality of DMT symbols in the first power mode and to switch to the second bit allocation table to receive the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for receiving starting with a predetermined one of the DMT symbols that follows the reception of the flag signal.

222. The protocol of claim 221, wherein the predetermined DMT symbol is a first DMT symbol that follows the reception of the flag signal.

223. The protocol of claim 207, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

224. The protocol of claim 207, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

225. A multicarrier transmitter communications protocol that operates in a low power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the protocol operable to exit the low power mode and to enter a full power mode comprising:

storing a second bit allocation table for modulating bits on to subchannels to be used for transmission at a second increased data rate during the full power mode;

synchronizing use of the second bit allocation table between the transmitter and a receiver by transmitting a flag signal; and

seamlessly entering the full power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

226. The protocol of claim 225, wherein the predetermined DMT symbol is a first DMT symbol that follows the transmission of the flag signal.

227. The protocol of claim 225, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

228. The protocol of claim 225, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

229. The protocol of claim 225, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

230. A multicarrier receiver communications protocol operating in a low power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, the protocol operable to exit the low power mode and to enter a full power mode comprising:

storing a second bit allocation table for demodulating bits from subchannels to be used for reception at a second increased data rate during the full power mode;

synchronizing use of the second bit allocation table between the receiver and a transmitter by receiving a flag signal; and

seamlessly entering the full power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols and receive at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

231. The protocol of claim 230, wherein the predetermined DMT symbol is a first DMT symbol that follows the reception of the flag signal.

232. The protocol of claim 230, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

233. The protocol of claim 230, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

234. The protocol of claim 230, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

235. A multicarrier transceiver communications protocol operating in a full power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the protocol operable to enter a low power mode comprising:

receiving from a second transceiver a message comprising at least one parameter of a second bit allocation table for modulating bits on to at least one subchannel to be used for transmitting at a second reduced data rate during the low power mode;

synchronizing use of the second bit allocation table between the transceiver and the second transceiver by transmitting a flag signal; and

seamlessly entering the low power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols, and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

236. The protocol of claim 235, wherein the predetermined DMT symbol is a first DMT symbol that follows the transmission of the flag signal.

237. The protocol of claim 235, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

238. The protocol of claim 235, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

239. The protocol of claim 235, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

240. A multicarrier transceiver communications protocol operating in a full power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, the protocol operable to enter a low power mode comprising:

transmitting to a second transceiver a message comprising at least one parameter of a second bit allocation table for demodulating bits from at least one subchannel to be used for receiving at a second reduced data rate during the low power mode;

synchronizing use of the second bit allocation table between the transceiver and the second transceiver by receiving a flag signal; and

seamlessly entering the low power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols, and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

241. The protocol of claim 240, wherein the predetermined DMT symbol is a first DMT symbol that follows the reception of the flag signal.

242. The protocol of claim 240, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

243. The protocol of claim 240, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

244. The protocol of claim 240, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

245. A multicarrier communication system transmitter protocol operable to use a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the protocol allowing seamless entering of a second power mode comprising:

storing a second bit allocation table to be used for transmitting codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the transmitter and a receiver;

seamlessly transitioning to the second power mode based on the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit codewords in the first power mode also being used to transmit codewords in the second power mode; and

transmitting codewords using the second bit allocation table.

246. The protocol of claim 245, wherein synchronizing includes sending the flag signal.

247. The protocol of claim 246, wherein the flag signal comprises ate least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

248. The protocol of claim 246, wherein at least one of the transmitter transmits the flag signal to the receiver and the receiver transmits the flag signal to the transmitter.

249. The protocol of claim 245, wherein the second power mode is a low power mode.

250. The protocol of claim 249, further comprising allocating zero bits to one or more carrier signals to achieve a transmission bit rate of approximately zero kilobits per second in the low power mode.

251. The protocol of claim 249, further comprising transmitting a pilot tone for timing recovery when operating in the low power mode.

252. The protocol of claim 249, further comprising periodically transmitting a sync symbol when operating in the low power mode.

253. The protocol of claim 246, further comprising using the first bit allocation table for transmitting a plurality of DMT symbols in the first power mode and switching to the second bit allocation table for transmitting the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for transmission starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal.

254. The protocol of claim 253, wherein the predetermined DMT symbol is a first DMT symbol that follows the transmission of the flag signal.

255. The protocol of claim 245, wherein the second power mode is a full power mode.

256. The protocol of claim 245, wherein the first power mode is a full power mode, and the second power mode is a low power mode.

257. The protocol of claim 245, wherein the first power mode is a low power mode, and the second power mode is a full power mode.

258. The protocol of claim 245, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

259. The protocol of claim 245, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

260. A multicarrier communication system receiver protocol that uses a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the protocol operable to seamlessly enter a second power mode comprising:

storing a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the receiver and a transmitter;

seamlessly transitioning to the second power mode based on the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to receive codewords in the first power mode also being used to receive codewords in the second power mode; and

receiving codewords using the second bit allocation table.

261. The protocol of claim 260, wherein the synchronizing includes at least one of the receiver and transmitter receiving the flag signal.

262. The protocol of claim 261, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

263. The protocol of claim 261, wherein at least one of the transmitter transmits the flag signal to the receiver and the receiver transmits the flag signal to the transmitter.

264. The protocol of claim 260, wherein the second power mode is a low power mode.

265. The protocol of claim 264, further comprising allocating zero bits to carrier signals to achieve a bit rate of approximately zero kilobits per second in the low power mode.

266. The protocol of claim 264, further comprising receiving a pilot tone for timing recovery when operating in the low power mode.

267. The protocol of claim 264, further comprising periodically receiving a sync symbol when operating in the low power mode.

268. The protocol of claim 260, further comprising using the first bit allocation table for receiving a plurality of DMT symbols in the first power mode and switching to the second bit allocation table for receiving the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for receiving starting with a predetermined one of the DMT symbols that follows the reception of the flag signal.

269. The protocol of claim 268, wherein the predetermined DMT symbol is a first DMT symbol that follows the reception of the flag signal.

270. The protocol of claim 260, wherein the second power mode is a full power mode.

271. The protocol of claim 260, wherein the first power mode is a full power mode, and the second power mode is a low power mode.

272. The protocol of claim 260, wherein the first power mode is a low power mode, and the second power mode is a full power mode.

273. The protocol of claim 260, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

274. The protocol of claim 260, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

275. A multicarrier communication system including a transmitter a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the system operable to seamlessly enter a second power mode comprising:

means for storing a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode; and

means for synchronizing use of the second bit allocation table between the transmitter and receiver, the multicarrier communication system seamlessly transitioning to the second power mode based on the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode also being used to transmit and receive codewords in the second power mode; and

means for transmitting and receiving codewords using the second bit allocation table.

276. The system of claim 275, wherein the means for synchronizing comprises at least one of a flag signal, a predefined signal, a sync symbol with a predefined phase shift, an inverted sync symbol and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

277. The system of claim 276, wherein the transmitter transmits the flag signal to the receiver.

278. The system of claim 276, wherein the receiver transmits the flag signal to the transmitter.

279. The system of claim 275, wherein the second power mode is a low power mode.

280. The system of claim 279, further comprising means for at least one of the transmitter and the receiver allocating zero bits to one or more carrier signals to achieve a transmission bit rate of approximately zero kilobits per second in the low power mode.

281. The system of claim 279, further comprising means for at least one of the transmitter and receiver transmitting a pilot tone for timing recovery when operating in the low power mode.

282. The system of claim 279, further comprising means for at least one of the transmitter and receiver periodically transmitting a sync symbol when operating in the low power mode.

283. The system of claim 279, wherein the receiver uses the first bit allocation table for transmitting a plurality of DMT symbols in the first power mode and switches to the second bit allocation table for transmitting the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for transmission starting with a predetermined one of the DMT symbols that follows the transmission of a flag signal.

284. The system of claim 283, wherein the predetermined DMT symbol is a first DMT symbol that follows the transmission of the flag signal.

285. The system of claim 275, wherein the second power mode is a full power mode.

286. The system of claim 275, wherein the first power mode is a full power mode, and the second power mode is a low power mode.

287. The system of claim 275, wherein the first power mode is a low power mode, and the second power mode is a full power mode.

288. The system of claim 276, wherein the receiver uses the first bit allocation table for receiving a plurality of DMT symbols in the first power mode and switches to the second bit allocation table for receiving the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for receiving starting with a predetermined one of the DMT symbols that follows the reception of the flag signal.

289. The system of claim 288, wherein the predetermined DMT symbol is a first DMT symbol that follows the reception of the flag signal.

290. The system of claim 275, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

291. The system of claim 275, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

292. A multicarrier transmitter operating in a low power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the transmitter exiting the low power mode and entering a full power mode comprising:

means for storing a second bit allocation table for modulating bits on to subchannels to be used for transmission at a second increased data rate during the full power mode;

means for synchronizing use of the second bit allocation table between the transmitter and a receiver, wherein the transmitter seamlessly enters the full power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmits at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

293. The system of claim 292, wherein the predetermined DMT symbol is a first DMT symbol that follows the transmission of a flag signal.

294. The system of claim 292, wherein the means for synchronizing comprises at least one of a flag signal, a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

295. The system of claim 292, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

296. The system of claim 292, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

297. A multicarrier receiver operating in a low power mode at a first data rate using a first bit allocation table to demodulating bits from subchannels in a plurality of DMT symbols, the receiver exiting the low power mode and entering a full power mode comprising:

means for storing a second bit allocation table for demodulating bits from subchannels to be used for reception at a second increased data rate during the full power mode; and

means for synchronizing use of the second bit allocation table between the receiver and a transmitter, wherein the receiver seamlessly enters the full power mode by using the second bit allocation table to demodulate bits from subchannels in the plurality of DMT symbols and receives at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of a flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

298. The system of claim 297, wherein the predetermined DMT symbol is the first DMT symbol that follows the reception of the flag signal.

299. The system of claim 297, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

300. The system of claim 297, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

301. The system of claim 297, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

302. A multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the transmitter entering a low power mode comprising:

means for receiving a message from a second transceiver including at least one parameter of a second bit allocation table for modulating bits on to at least one subchannel to be used for transmitting at a second reduced data rate during the low power mode; and

an the means for synchronizing use of the second bit allocation table between the transceiver and the second transceiver with a flag signal, wherein the transceiver seamlessly enters the low power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols, and transmits at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

303. The system of claim 302, wherein the predetermined DMT symbol is a first DMT symbol that follows the transmission of the flag signal.

304. The system of claim 302, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

305. The system of claim 302, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

306. The system of claim 302, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

307. A multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, the receiver entering a low power mode comprising:

means for transmitting a message to a second transceiver comprising at least one parameter of a second bit allocation table for demodulating bits from at least one subchannel to be used for receiving at a second reduced data rate during the low power mode;

means for synchronizing use of the second bit allocation table between the transceiver and the second transceiver, wherein the transceiver seamlessly enters the low power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols, and receives at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of a flag signal, wherein the plurality of DMT symbols are decoupled from at least one of a plurality of codewords and a plurality of ADSL frames in at least one of the full and low power modes.

308. The system of claim 307, wherein the predetermined DMT symbol is a first DMT symbol that follows the reception of the flag signal.

309. The system of claim 307, wherein the means for synchronizing is at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

310. The system of claim 307, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

311. The system of claim 307, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

312. A multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the system seamlessly entering a second power mode comprising:

means for storing a second bit allocation table to be used for transmitting codewords at a second bit rate in the second power mode; and

means for synchronizing use of the second bit allocation table between the transmitter and a receiver wherein the transmitter seamlessly transitions to the second power mode based on the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit codewords in the first power mode also being used to transmit codewords in the second power mode; and

means for transmitting codewords using the second bit allocation table.

313. The system of claim 312, wherein synchronizing includes sending a flag signal to at least one of the transmitter and receiver.

314. The system of claim 313, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

315. The system of claim 312, wherein at least one of the transmitter transmits the flag signal to the receiver and the receiver transmits the flag signal to the transmitter.

316. The system of claim 312, wherein the second power mode is a low power mode.

317. The system of claim 316, wherein the transmitter allocates zero bits to one or more carrier signals to achieve a transmission bit rate of approximately zero kilobits per second in the low power mode.

318. The system of claim 316, wherein the transmitter transmits a pilot tone for timing recovery when operating in the low power mode.

319. The system of claim 316, wherein the transmitter periodically transmitting a sync symbol when operating in the low power mode.

320. The system of claim 313, wherein the transmitter uses the first bit allocation table for transmitting a plurality of DMT symbols in the first power mode and switches to the second bit allocation table for transmitting the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for transmission starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal.

321. The system of claim 320, wherein the predetermined DMT symbol is a first DMT symbol that follows the transmission of the flag signal.

322. The system of claim 312, wherein the second power mode is a full power mode.

323. The system of claim 312, wherein the first power mode is a full power mode, and the second power mode is a low power mode.

324. The system of claim 312, wherein the first power mode is a low power mode, and the second power mode is a full power mode.

325. The system of claim 312, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

326. The system of claim 312, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

327. A multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the receiver seamlessly entering a second power mode comprising:

means for storing a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode; and

means for synchronizing use of the second bit allocation table between the receiver and a transmitter, wherein the receiver seamlessly transitions to the second power mode based on the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to receive codewords in the first power mode also being used to receive codewords in the second power mode; and

means for receiving codewords using the second bit allocation table.

328. The system of claim 327, wherein the synchronizing includes receiving a flag signal at at least one of the transmitter and receiver.

329. The system of claim 328, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and at least one non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

330. The system of claim 328, wherein at least one of the transmitter transmits the flag signal to the receiver and the receiver transmits the flag signal to the transmitter.

331. The system of claim 327, wherein the second power mode is a low power mode.

332. The system of claim 331, wherein the receiver allocates zero bits to carrier signals to achieve a bit rate of approximately zero kilobits per second in the low power mode.

333. The system of claim 331, wherein the receiver receives a pilot tone for timing recovery when operating in the low power mode.

334. The system of claim 331, wherein the receiver periodically receiving a sync symbol when operating in the low power mode.

335. The system of claim 327, wherein the receiver uses the first bit allocation table for receiving a plurality of DMT symbols in the first power mode and switching to the second bit allocation table for receiving the plurality of the DMT symbols in the second power mode, wherein the second bit allocation table is used for receiving starting with a predetermined one of the DMT symbols that follows the reception of a flag signal.

336. The system of claim 335, wherein the predetermined DMT symbol is a first DMT symbol that follows the receiving of the flag signal.

337. The system of claim 328, wherein the second power mode is a full power mode.

338. The system of claim 327, wherein the first power mode is a full power mode, and the second power mode is a low power mode.

339. The system of claim 327, wherein the first power mode is a low power mode, and the second power mode is a full power mode.

340. The system of claim 327, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

341. The system of claim 327, wherein each bit allocation table specifies the data rate for each latency path in a multiple latency path multicarrier system.

342. In a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, a method for seamlessly entering a second power mode, the method comprising:

storing a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the transmitter and receiver; and

seamlessly entering the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a plurality of DMT symbols are decoupled from at least one of the plurality of codewords and a plurality of ADSL frames in at least one of the first and second power modes.

343. The method of claim 342, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

344. The method of claim 342, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

345. In a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, a method for seamlessly entering a second power mode, the method comprising:

storing a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the transmitter and receiver; and

seamlessly entering the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

346. The method of claim 345, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

347. The method of claim 345, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

348. In a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, a method for seamlessly entering a second power mode, the method comprising:

storing a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second, bit rate in the second power mode;

synchronizing use of the second bit allocation table between the transmitter and receiver; and

seamlessly entering the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode,

a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the first power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the second power mode, and

the number of bits in a DMT symbol (N_BAT) for the first power mode is different than the number of bits in a DMT symbol (N_BAT) for the second power mode.

349. The method of claim 348, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

350. The method of claim 348, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

351. In a multicarrier transmitter operating in a low power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, a method for exiting the low power mode and entering a full power mode, the method comprising:

storing a second bit allocation table for modulating bits on to subchannels to be used for transmission at a second increased data rate during the full power mode;

synchronizing use of the second bit allocation table between the transmitter and a receiver by transmitting a flag signal; and

seamlessly entering the full power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

352. The method of claim 351, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

353. The method of claim 351, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

354. In a multicarrier transmitter operating in a low power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, a method for exiting the low power mode and entering a full power mode, the method comprising:

storing a second bit allocation table for modulating bits on to subchannels to be used for transmission at a second increased data rate during the full power mode;

synchronizing use of the second bit allocation table between the transmitter and a receiver by transmitting a flag signal; and

seamlessly entering the full power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

355. The method of claim 354, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

356. The method of claim 354, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

357. In a multicarrier receiver operating in a low power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, a method for exiting the low power mode and entering a full power mode, the method comprising:

storing a second bit allocation table for demodulating bits from subchannels to be used for reception at a second increased data rate during the full power mode;

synchronizing use of the second bit allocation table between the receiver and a transmitter by receiving a flag signal; and

seamlessly entering the full power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

358. The method of claim 357, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

359. The method of claim 357, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

360. In a multicarrier receiver operating in a low power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, a method for exiting the low power mode and entering a full power mode, the method comprising:

storing a second bit allocation table for demodulating bits from subchannels to be used for reception at a second increased data rate during the full power mode;

synchronizing use of the second bit allocation table between the receiver and a transmitter by receiving a flag signal; and

seamlessly entering the full power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

361. The method of claim 360, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

362. The method of claim 360, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

363. In a multicarrier transmitter operating in a full power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, a method for entering a low power mode, the method comprising:

receiving from a second transceiver a message comprising at least one parameter of a second bit allocation table for modulating bits on to at least one subchannel to be used for transmission at a second reduced data rate during the low power mode;

synchronizing use of the second bit allocation table between the transceiver and the second transceiver by transmitting a flag signal; and

seamlessly entering the low power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols, and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

364. The method of claim 363, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

365. The method of claim 363, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

366. In a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, a method for entering a low power mode, the method comprising:

receiving from a second transceiver a message comprising at least one parameter of a second bit allocation table for modulating bits on to at least one subchannel to be used for transmission at a second reduced data rate during the low power mode;

synchronizing use of the second bit allocation table between the transceiver and the second transceiver by transmitting a flag signal; and

seamlessly entering the low power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

367. The method of claim 366, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

368. The method of claim 366, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

369. In a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, a method for entering a low power mode, the method comprising:

transmitting to a second transceiver a message comprising at least one parameter of a second bit allocation table for demodulating bits from at least one subchannel to be used for receiving at a second reduced data rate during the low power mode;

synchronizing use of the second bit allocation table between the transceiver and the second transceiver by receiving a flag signal; and

seamlessly entering the low power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols, and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

370. The method of claim 369, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

371. The method of claim 369, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

372. In a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, a method for entering a low power mode, the method comprising:

transmitting to a second transceiver a message comprising at least one parameter of a second bit allocation table for demodulating bits from at least one subchannel to be used for receiving at a second reduced data rate during the low power mode;

synchronizing use of the second bit allocation table between the transceiver and the second transceiver by receiving a flag signal; and

seamlessly entering the low power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols, and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

373. The method of claim 372, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

374. The method of claim 372, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

375. In a multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, a method for seamlessly entering a second power mode, the method comprising:

storing a second bit allocation table to be used for transmitting codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the transmitter and a receiver; and

seamlessly entering the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit codewords in the first power mode are also used to transmit codewords in the second power mode, and a plurality of DMT symbols are decoupled from at least one of the plurality of codewords and a plurality of ADSL frames in at least one of the first and second power modes.

376. The method of claim 375, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

377. The method of claim 375, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

378. In a multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, a method for seamlessly entering a second power mode, the method comprising:

storing a second bit allocation table be used for transmitting codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the transmitter and a receiver; and

seamlessly entering the second power mode by using the second bit allocation table to transmit codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit codewords in the first power mode are also used to transmit codewords in the second power mode, and a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

379. The method of claim 378, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

380. The method of claim 378, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

381. In a multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, a method for seamlessly entering a second power mode, the method comprising:

storing a second bit allocation table to be used for transmitting codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the transmitter and a receiver; and

seamlessly entering the second power mode by using the second bit allocation table to transmit codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode,

a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the first power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the second power mode, and

the number of bits in a DMT symbol (N_BAT) for the first power mode is different than the number of bits in a DMT symbol (N_BAT) for the second power mode.

382. The method of claim 381, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

383. The method of claim 381, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

384. In a multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, a method for seamlessly entering a second power mode, the method comprising:

storing a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the receiver and a transmitter; and

seamlessly entering the second power mode by using the second bit allocation table receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a plurality of DMT symbols are decoupled from at least one of the plurality of codewords and a plurality of ADSL frames in at least one of the first and second power modes.

385. The method of claim 384, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

386. The method of claim 384, wherein synchronizing includes receiving a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

387. In a multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, a method for seamlessly entering a second power mode, the method comprising:

storing a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the receiver and a transmitter; and

seamlessly entering the second power mode by using the second bit allocation table to receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

388. The method of claim 387, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

389. The method of claim 387, wherein synchronizing includes receiving a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

390. In a multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, a method for seamlessly entering a second power mode, the method comprising:

storing a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the receiver and transmitter; and

seamlessly entering the second power mode by using the second bit allocation table to receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode,

a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the first power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the second power mode, and

the number of bits in a DMT symbol (N_BAT) for the first power mode is different than the number of bits in a DMT symbol (N_BAT) for the second power mode.

391. The method of claim 390, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

392. The method of claim 390, wherein synchronizing includes receiving a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

393. An information storage media comprising information for a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, instructions on the media operable to seamlessly enter a second power mode comprising:

information that stores a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode;

information that synchronizes use of the second bit allocation table between the transmitter and receiver; and

information operable to seamlessly enter the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a plurality of DMT symbols are decoupled from at least one of the plurality of codewords and a plurality of ADSL frames in at least one of the first and second power modes.

394. The media of claim 393, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

395. The media of claim 393, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

396. An information storage media comprising information for a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, instructions on the media operable to seamlessly enterer a second power mode comprising:

information that stores a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode;

information that synchronizes use of the second bit allocation table between the transmitter and receiver; and

information operable to seamlessly enter the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

397. The media of claim 396, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

398. The media of claim 396, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

399. An information storage media comprising information for a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, instructions on the media operable to seamlessly enterer a second power mode comprising:

information that stores a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode;

information that synchronizes use of the second bit allocation table between the transmitter and receiver; and

information operable to seamlessly enter the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode,

a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the first power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the second power mode, and

the number of bits in a DMT symbol (N_BAT) for the first power mode is different than the number of bits in a DMT symbol (N_BAT) for the second power mode.

400. The media of claim 399, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

401. The media of claim 399, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

402. An information storage media comprising information for a multicarrier transmitter operating in a low power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, instructions on the media operable to exit the low power mode and enter a full power mode comprising:

information that stores a second bit allocation table for modulating bits on to subchannels to be used for transmission at a second increased data rate during the full power mode;

information that synchronizes use of the second bit allocation table between the transmitter and a receiver by transmitting a flag signal; and

information operable to seamlessly enter the full power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

403. The media of claim 402, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

404. The media of claim 402, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

405. An information storage media comprising information for a multicarrier transmitter operating in a low power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, instructions on the media operable to exit the low power mode and enter a full power mode comprising:

information that stores a second bit allocation table for modulating bits on to subchannels to be used for transmission at a second increased data rate during the fill power mode;

information that synchronizes use of the second bit allocation table between the transmitter and a receiver by transmitting a flag signal; and

information operable to seamlessly enter the full power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

406. The media of claim 405, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

407. The media of claim 405, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

408. An information storage media comprising information for a multicarrier receiver operating in a low power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, instructions on the media operable to exit the low power mode and enter a full power mode comprising:

information that stores a second bit allocation table for demodulating bits from subchannels to be used for reception at a second increased data rate during the full power mode;

information that synchronizes use of the second bit allocation table between the receiver and a transmitter by receiving a flag signal; and

information operable to seamlessly enter the full power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

409. The media of claim 408, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

410. The media of claim 408, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

411. An information storage media comprising information for a multicarrier receiver operating in a low power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, instructions on the media operable to exit the low power mode and enter a full power mode comprising:

information that stores a second bit allocation table for demodulating bits from subchannels to be used for reception at a second increased data rate during the full power mode;

information that synchronizes use of the second bit allocation table between the receiver and a transmitter by receiving a flag signal; and

information operable to seamlessly enter the full power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

412. The media of claim 411, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

413. The media of claim 411, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

414. An information storage media comprising information for a multicarrier transmitter operating in a full power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, instructions on the media operable to enter a low power mode comprising:

information that receives from a second transceiver a message comprising at least one parameter of a second bit allocation table for modulating bits on to at least one subchannel to be used for transmission at a second reduced data rate during the low power mode;

information that synchronizes use of the second bit allocation table between the transceiver and the second transceiver by transmitting a flag signal; and

information operable to seamlessly enter the low power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols, and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

415. The media of claim 414, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

416. The media of claim 414, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

417. An information storage media comprising information for a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, instructions on the media operable to enter a low power mode comprising:

information that receives from a second transceiver a message comprising at least one parameter of a second bit allocation table for modulating bits on to at least one subchannel to be used for transmission at a second reduced data rate during the low power mode;

information that synchronizes use of the second bit allocation table between the transceiver and the second transceiver by transmitting a flag signal; and

information operable to seamlessly enter the low power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

418. The media of claim 417, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

419. The media of claim 417, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

420. An information storage media comprising information for a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, instructions on the media operable to enter a low power mode comprising:

information that transmits to a second transceiver a message comprising at least one parameter of a second bit allocation table for demodulating bits from at least one subchannel to be used for receiving at a second reduced data rate during the low power mode;

information that synchronizes use of the second bit allocation table between the transceiver and the second transceiver by receiving a flag signal; and

information operable to seamlessly enter the low power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols, and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

421. The media of claim 420, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

422. The media of claim 420, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

423. An information storage media comprising information for a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, instructions on the media operable to enter a low power mode comprising:

information that transmits to a second transceiver a message comprising at least one parameter of a second bit allocation table for demodulating bits from at least one subchannel to be used for receiving at a second reduced data rate during the low power mode;

information that synchronizes use of the second bit allocation table between the transceiver and the second transceiver by receiving a flag signal; and

information operable to seamlessly enter the low power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols, and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

424. The media of claim 423, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

425. The media of claim 423, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

426. An information storage media comprising information for a multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, instructions on the media operable to seamlessly enter a second power mode comprising:

information that stores a second bit allocation table to be used for transmitting codewords at a second bit rate in the second power mode;

information that synchronizes use of the second bit allocation table between the transmitter and a receiver; and

information operable to seamlessly enter the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit codewords in the first power mode are also used to transmit codewords in the second power mode, and a plurality of DMT symbols are decoupled from at least one of the plurality of codewords and a plurality of ADSL frames in at least one of the first and second power modes.

427. The media of claim 426, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

428. The media of claim 426, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

429. An information storage media comprising information for a multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, instructions on the media operable to seamlessly enter a second power mode comprising:

information that stores a second bit allocation table be used for transmitting codewords at a second bit rate in the second power mode;

information that synchronizes use of the second bit allocation table between the transmitter and a receiver; and

information operable to seamlessly enter the second power mode by using the second bit allocation table to transmit codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit codewords in the first power mode are also used to transmit codewords in the second power mode, and a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

430. The media of claim 429, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

431. The media of claim 429, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

432. An information storage media comprising information for a multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, instructions on the media operable to seamlessly enter a second power mode comprising:

information that stores a second bit allocation table to be used for transmitting codewords at a second bit rate in the second power mode;

information that synchronizes use of the second bit allocation table between the transmitter and a receiver; and

information operable to seamlessly enter the second power mode by using the second bit allocation table to transmit codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode,

a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the first power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the second power mode, and

the number of bits in a DMT symbol (N_BAT) for the first power mode is different than the number of bits in a DMT symbol (N_BAT) for the second power mode.

433. The media of claim 432, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

434. The media of claim 432, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

435. An information storage media comprising information for a multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, instructions on the media operable to seamlessly enter a second power mode comprising:

information that stores a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode;

information that synchronizes use of the second bit allocation table between the receiver and a transmitter; and

information operable to seamlessly enter the second power mode by using the second bit allocation table receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a plurality of DMT symbols are decoupled from at least one of the plurality of codewords and a plurality of ADSL frames in at least one of the first and second power modes.

436. The media of claim 435, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

437. The media of claim 435, wherein synchronizing includes receiving a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

438. An information storage media comprising information for multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, instructions on the media operable to seamlessly enter a second power mode comprising:

information that stores a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode;

information that synchronizes use of the second bit allocation table between the receiver and a transmitter; and

information operable to seamlessly enter the second power mode by using the second bit allocation table to receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

439. The media of claim 438, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

440. The media of claim 438, wherein synchronizing includes receiving a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

441. An information storage media comprising information for a multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, instructions on the media operable to seamlessly enter a second power mode comprising:

information that stores a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode;

information that synchronizes use of the second bit allocation table between the receiver and transmitter; and

information operable to seamlessly enter the second power mode by using the second bit allocation table to receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode,

a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the first power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the second power mode, and

the number of bits in a DMT symbol (N_BAT) for the first power mode is different than the number o f bits in a DMT symbol (N_BAT) for the second power mode.

442. The media of claim 441, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

443. The media of claim 441, wherein synchronizing includes receiving a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

444. In a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the system operable to seamlessly enter a second power mode comprising:

a plurality of memory devices that store a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode; and

a flag signal that synchronizes use of the second bit allocation table between the transmitter and receiver, the multicarrier communication system seamlessly entering the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a plurality of DMT symbols are decoupled from at least one of the plurality of codewords and a plurality of ADSL frames in at least one of the first and second power modes.

445. The system of claim 444, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

446. The system of claim 444, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

447. In a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the system operable to seamlessly enter a second power mode comprising:

a plurality of memory devices that store a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode; and

a flag signal that synchronizes use of the second bit allocation table between the transmitter and receiver, the multicarrier communication system seamlessly entering the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

448. The system of claim 447, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

449. The system of claim 447, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

450. In a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the system operable to seamlessly enter a second power mode comprising:

a plurality of memory devices that store a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode; and

a flag signal that synchronizes use of the second bit allocation table between the transmitter and receiver, the multicarrier communication system seamlessly entering the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode,

a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the first power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the second power mode, and

the number of bits in a DMT symbol (N_BAT) for the first power mode is different than the number of bits in a DMT symbol (N_BAT) for the second power mode.

451. The system of claim 450, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

452. The system of claim 450, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

453. In a multicarrier transmitter operating in a low power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the transmitter exiting the low power mode and entering a full power mode comprising:

a memory that stores a second bit allocation table for modulating bits on to subchannels to be used for transmission at a second increased data rate during the full power mode; and

a flag signal that synchronizes use of the second bit allocation table between the transmitter and a receiver, wherein the transmitter seamlessly enters the full power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

454. The system of claim 453, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

455. The system of claim 453, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

456. In a multicarrier transmitter operating in a low power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the transmitter exiting the low power mode and entering a full power mode comprising:

a memory that stores a second bit allocation table for modulating bits on to subchannels to be used for transmission at a second increased data rate during the full power mode; and

a flag signal that synchronizes use of the second bit allocation table between the transmitter and a receiver, wherein the transmitter seamlessly enters the full power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

457. The system of claim 456, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

458. The system of claim 456, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

459. In a multicarrier receiver operating in a low power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, the receiver exiting the low power mode and entering a full power mode comprising:

a memory that stores a second bit allocation table for demodulating bits from subchannels to be used for reception at a second increased data rate during the full power mode; and

a flag signal that synchronizes use of the second bit allocation table between the receiver and a transmitter, wherein the receiver seamlessly enters the full power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

460. The system of claim 459, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

461. The system of claim 459, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

462. In a multicarrier receiver operating in a low power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, the receiver exiting the low power mode and entering a full power mode comprising:

a memory that stores a second bit allocation table for demodulating bits from subchannels to be used for reception at a second increased data rate during the full power mode; and

a flag signal that synchronizes use of the second bit allocation table between the receiver and a transmitter, wherein the receiver seamlessly enters the full power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

463. The system of claim 462, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

464. The system of claim 462, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

465. In a multicarrier transmitter operating in a full power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the transmitter entering a low power mode comprising:

a message received from a second transceiver comprising at least one parameter of a second bit allocation table for modulating bits on to at least one subchannel to be used for transmission at a second reduced data rate during the low power mode; and

a flag signal that synchronizes use of the second bit allocation table between the transceiver and the second transceiver, wherein the transmitter seamlessly enters the low power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols, and transmits at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

466. The system of claim 465, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

467. The system of claim 465, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

468. In a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the transceiver entering a low power mode comprising:

a message received from a second transceiver comprising at least one parameter of a second bit allocation table for modulating bits on to at least one subchannel to be used for transmission at a second reduced data rate during the low power mode; and

a flag signal that synchronizes use of the second bit allocation table between the transceiver and the second transceiver, wherein the transceiver seamlessly enters the low power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmits at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

469. The system of claim 468, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

470. The system of claim 468, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

471. In a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, the transceiver entering a low power mode comprising:

a message transmitted to a second transceiver comprising at least one parameter of a second bit allocation table for demodulating bits from at least one subchannel to be used for receiving at a second reduced data rate during the low power mode; and

a flag signal that synchronizes use of the second bit allocation table between the transceiver and the second transceiver, wherein the transceiver seamlessly enters the low power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols, and receives at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

472. The system of claim 471, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

473. The system of claim 471, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

474. In a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, the transceiver entering a low power mode comprising:

a message transmitted to a second transceiver comprising at least one parameter of a second bit allocation table for demodulating bits from at least one subchannel to be used for receiving at a second reduced data rate during the low power mode; and

a flag signal that synchronizes use of the second bit allocation table between the transceiver and the second transceiver, wherein the transceiver seamlessly enters the low power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols, and receives at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

475. The system of claim 474, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

476. The system of claim 474, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

477. In a multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the transmitter seamlessly entering a second power mode comprising:

a memory that stores a second bit allocation table to be used for transmitting codewords at a second bit rate in the second power mode; and

a flag signal that synchronizes use of the second bit allocation table between the transmitter and a receiver, wherein the transmitter seamlessly enters the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit codewords in the first power mode are also used to transmit codewords in the second power mode, and a plurality of DMT symbols are decoupled from at least one of the plurality of codewords and a plurality of ADSL frames in at least one of the first and second power modes.

478. The system of claim 477, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

479. The system of claim 477, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

480. In a multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the transmitter seamlessly entering a second power mode comprising:

a memory that stores a second bit allocation table be used for transmitting codewords at a second bit rate in the second power mode; and

a flag signal that synchronizes use of the second bit allocation table between the transmitter and a receiver, wherein the transmitter seamlessly enters the second power mode by using the second bit allocation table to transmit codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit codewords in the first power mode are also used to transmit codewords in the second power mode, and a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

481. The system of claim 480, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

482. The system of claim 480, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

483. In a multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the transmitter seamlessly entering a second power mode comprising:

a memory that stores a second bit allocation table to be used for transmitting codewords at a second bit rate in the second power mode; and

a flag signal that synchronizes use of the second bit allocation table between the transmitter and a receiver, wherein the transmitter seamlessly enters the second power mode by using the second bit allocation table to transmit codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode,

a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the first power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the second power mode, and

the number of bits in a DMT symbol (N_BAT) for the first power mode is different than the number of bits in a DMT symbol (N_BAT) for the second power mode.

484. The system of claim 483, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

485. The system of claim 483, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

486. In a multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the receiver seamlessly entering a second power mode comprising:

a memory that stores a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode; and

a flag signal that synchronizes use of the second bit allocation table between the receiver and a transmitter, wherein the receiver seamlessly enters the second power mode by using the second bit allocation table receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a plurality of DMT symbols are decoupled from at least one of the plurality of codewords and a plurality of ADSL frames in at least one of the first and second power modes.

487. The system of claim 486, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

488. The system of claim 486, wherein synchronizing includes receiving a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

489. In a multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the receiver seamlessly entering a second power mode comprising:

a memory that stores a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode; and

a flag signal that synchronizes use of the second bit allocation table between the receiver and a transmitter, wherein the receiver seamlessly enters the second power mode by using the second bit allocation table to receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

490. The system of claim 489, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

491. The system of claim 489, wherein synchronizing includes receiving a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

492. In a multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the receiver seamlessly entering a second power mode comprising:

a memory that stores a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode; and

a flag signal that synchronizes use of the second bit allocation table between the receiver and transmitter, wherein the receiver seamlessly enters the second power mode by using the second bit allocation table to receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode,

a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the first power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the second power mode, and

the number of bits in a DMT symbol (N_BAT) for the first power mode is different than the number of bits in a DMT symbol (N_BAT) for the second power mode.

493. The system of claim 492, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

494. The system of claim 492, wherein synchronizing includes receiving a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

495. A communication protocol for a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the protocol operable to seamlessly entering a second power mode comprising:

storing a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the transmitter and receiver; and

seamlessly entering the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a plurality of DMT symbols are decoupled from at least one of the plurality of codewords and a plurality of ADSL frames in at least one of the first and second power modes.

496. The protocol of claim 495, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

497. The protocol of claim 495, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

498. A communication protocol for a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the protocol operable to seamlessly enter a second power mode comprising:

storing a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the transmitter and receiver; and

seamlessly entering the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

499. The protocol of claim 498, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

500. The protocol of claim 498, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

501. A communication protocol for a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the protocol operable to seamlessly entering a second power mode comprising:

storing a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the transmitter and receiver; and

seamlessly entering the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode,

a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the first power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the second power mode, and

the number of bits in a DMT symbol (N_BAT) for the first power mode is different than the number of bits in a DMT symbol (N_BAT) for the second power mode.

502. The protocol of claim 501, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

503. The protocol of claim 501, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

504. A communication protocol for a multicarrier transmitter operating in a low power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the protocol operable to exit the low power mode and enter a full power mode comprising:

storing a second bit allocation table for modulating bits on to subchannels to be used for transmission at a second increased data rate during the full power mode;

synchronizing use of the second bit allocation table between the transmitter and a receiver by transmitting a flag signal; and

seamlessly entering the full power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

505. The protocol of claim 504, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

506. The protocol of claim 504, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

507. A communication protocol for a multicarrier transmitter operating in a low power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the protocol operable to exit the low power mode and enter a full power mode comprising:

storing a second bit allocation table for modulating bits on to subchannels to be used for transmission at a second increased data rate during the full power mode;

synchronizing use of the second bit allocation table between the transmitter and a receiver by transmitting a flag signal; and

seamlessly entering the full power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

508. The protocol of claim 507, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

509. The protocol of claim 507, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

510. A communication protocol for a multicarrier receiver operating in a low power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, the protocol operable to exit the low power mode and enter a full power mode comprising:

storing a second bit allocation table for demodulating bits from subchannels to be used for reception at a second increased data rate during the full power mode;

synchronizing use of the second bit allocation table between the receiver and a transmitter by receiving a flag signal; and

seamlessly entering the full power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

511. The protocol of claim 510, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

512. The protocol of claim 510, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

513. A communication protocol for a multicarrier receiver operating in a low power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, the protocol operable to exit the low power mode and enter a full power mode comprising:

storing a second bit allocation table for demodulating bits from subchannels to be used for reception at a second increased data rate during the full power mode;

synchronizing use of the second bit allocation table between the receiver and a transmitter by receiving a flag signal; and

seamlessly entering the full power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

514. The protocol of claim 513, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

515. The protocol of claim 513, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

516. A communication protocol for a multicarrier transmitter operating in a full power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the protocol operable to enter a low power mode comprising:

receiving from a second transceiver a message comprising at least one parameter of a second bit allocation table for modulating bits on to at least one subchannel to be used for transmission at a second reduced data rate during the low power mode;

synchronizing use of the second bit allocation table between the transceiver and the second transceiver by transmitting a flag signal; and

seamlessly entering the low power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols, and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

517. The protocol of claim 516, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

518. The protocol of claim 516, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

519. A communication protocol for a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the protocol operable to enter a low power mode comprising:

receiving from a second transceiver a message comprising at least one parameter of a second bit allocation table for modulating bits on to at least one subchannel to be used for transmission at a second reduced data rate during the low power mode;

synchronizing use of the second bit allocation table between the transceiver and the second transceiver by transmitting a flag signal; and

seamlessly entering the low power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

520. The protocol of claim 519, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

521. The protocol of claim 519, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

522. A communication protocol for a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, the protocol operable to enter a low power mode comprising:

transmitting to a second transceiver a message comprising at least one parameter of a second bit allocation table for demodulating bits from at least one subchannel to be used for receiving at a second reduced data rate during the low power mode;

synchronizing use of the second bit allocation table between the transceiver and the second transceiver by receiving a flag signal; and

seamlessly entering the low power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols, and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

523. The protocol of claim 522, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

524. The protocol of claim 522, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

525. A communication protocol for a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, the protocol operable to enter a low power mode comprising:

transmitting to a second transceiver a message comprising at least one parameter of a second bit allocation table for demodulating bits from at least one subchannel to be used for receiving at a second reduced data rate during the low power mode;

synchronizing use of the second bit allocation table between the transceiver and the second transceiver by receiving a flag signal; and

seamlessly entering the low power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols, and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

526. The protocol of claim 525, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

527. The protocol of claim 525, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

528. A communication protocol for a multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the protocol operable to seamlessly enter a second power mode comprising:

storing a second bit allocation table to be used for transmitting codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the transmitter and a receiver; and

seamlessly entering the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit codewords in the first power mode are also used to transmit codewords in the second power mode, and a plurality of DMT symbols are decoupled from at least one of the plurality of codewords and a plurality of ADSL frames in at least one of the first and second power modes.

529. The protocol of claim 528, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

530. The protocol of claim 528, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

531. A communication protocol for a multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the protocol operable to seamlessly enter a second power mode comprising:

storing a second bit allocation table be used for transmitting codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the transmitter and a receiver; and

seamlessly entering the second power mode by using the second bit allocation table to transmit codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit codewords in the first power mode are also used to transmit codewords in the second power mode, and a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

532. The protocol of claim 531, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

533. The protocol of claim 531, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

534. A communication protocol for a multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the protocol operable to seamlessly enter a second power mode comprising:

storing a second bit allocation table to be used for transmitting codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the transmitter and a receiver; and

seamlessly entering the second power mode by using the second bit allocation table to transmit codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode,

a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the first power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the second power mode, and

the number of bits in a DMT symbol (N_BAT) for the first power mode is different than the number of bits in a DMT symbol (N_BAT) for the second power mode.

535. The protocol of claim 534, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

536. The protocol of claim 534, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

537. A communication protocol for a multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the protocol operable to seamlessly enter a second power mode comprising:

storing a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the receiver and a transmitter; and

seamlessly entering the second power mode by using the second bit allocation table receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a plurality of DMT symbols are decoupled from at least one of the plurality of codewords and a plurality of ADSL frames in at least one of the first and second power modes.

538. The protocol of claim 537, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

539. The protocol of claim 537, wherein synchronizing includes receiving a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

540. A communication protocol for a multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the protocol operable to seamlessly enter a second power mode comprising:

storing a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the receiver and a transmitter; and

seamlessly entering the second power mode by using the second bit allocation table to receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

541. The protocol of claim 540, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

542. The protocol of claim 540, wherein synchronizing includes receiving a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

543. A communication protocol for a multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the protocol operable to seamlessly enter a second power mode comprising:

storing a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode;

synchronizing use of the second bit allocation table between the receiver and transmitter; and

seamlessly entering the second power mode by using the second bit allocation table to receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode,

a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the first power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the second power mode, and

the number of bits in a DMT symbol (N_BAT) for the first power mode is different than the number of bits in a DMT symbol (N_BAT) for the second power mode.

544. The protocol of claim 543, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

545. The protocol of claim 543, wherein synchronizing includes receiving a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

546. In a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the system operable to seamlessly enter a second power mode comprising:

means for storing a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode;

means for synchronizing use of the second bit allocation table between the transmitter and receiver; and

means for seamlessly entering the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a plurality of DMT symbols are decoupled from at least one of the plurality of codewords and a plurality of ADSL frames in at least one of the first and second power modes.

547. The system of claim 546, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

548. The system of claim 546, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

549. In a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the system operable to seamlessly enter a second power mode comprising:

means for storing a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode;

means for synchronizing use of the second bit allocation table between the transmitter and receiver; and

means for seamlessly entering the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

550. The system of claim 549, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

551. The system of claim 549, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

552. In a multicarrier communication system including a transmitter and a receiver, the transmitter and receiver using a first bit allocation table to transmit and receive, respectively, a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the system operable to seamlessly enter a second power mode comprising:

means for storing a second bit allocation table at the receiver and at the transmitter to be used for receiving and transmitting, respectively, codewords at a second bit rate in the second power mode;

means for synchronizing use of the second bit allocation table between the transmitter and receiver; and

means for seamlessly entering the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode,

a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the first power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the second power mode, and

the number of bits in a DMT symbol (N_BAT) for the first power mode is different than the number of bits in a DMT symbol (N_BAT) for the second power mode.

553. The system of claim 552, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

554. The system of claim 552, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

555. In a multicarrier transmitter operating in a low power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the system operable to exit the low power mode and enter a full power mode comprising:

means for storing a second bit allocation table for modulating bits on to subchannels to be used for transmission at a second increased data rate during the full power mode;

means for synchronizing use of the second bit allocation table between the transmitter and a receiver by transmitting a flag signal; and

means for seamlessly entering the full power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

556. The system of claim 555, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

557. The system of claim 555, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

558. In a multicarrier transmitter operating in a low power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the system operable to exit the low power mode and enter a full power mode comprising:

means for storing a second bit allocation table for modulating bits on to subchannels to be used for transmission at a second increased data rate during the full power mode;

means for synchronizing use of the second bit allocation table between the transmitter and a receiver by transmitting a flag signal; and

means for seamlessly entering the full power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

559. The system of claim 558, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

560. The system of claim 558, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

561. In a multicarrier receiver operating in a low power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, the system operable to exit the low power mode and enter a full power mode comprising:

means for storing a second bit allocation table for demodulating bits from subchannels to be used for reception at a second increased data rate during the full power mode;

means for synchronizing use of the second bit allocation table between the receiver and a transmitter by receiving a flag signal; and

means for seamlessly entering the full power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

562. The system of claim 561, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

563. The system of claim 561, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

564. In a multicarrier receiver operating in a low power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, the system operable to exit the low power mode and enter a full power mode comprising:

means for storing a second bit allocation table for demodulating bits from subchannels to be used for reception at a second increased data rate during the full power mode;

means for synchronizing use of the second bit allocation table between the receiver and a transmitter by receiving a flag signal; and

means for seamlessly entering the full power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

565. The system of claim 564, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

566. The system of claim 564, wherein the flag signal comprises at least one of a redefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

567. In a multicarrier transmitter operating in a full power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the system operable to enter a low power mode comprising:

means for receiving from a second transceiver a message comprising at least one parameter of a second bit allocation table for modulating bits on to at least one subchannel to be used for transmission at a second reduced data rate during the low power mode;

means for synchronizing use of the second bit allocation table between the transceiver and the second transceiver by transmitting a flag signal; and

means for seamlessly entering the low power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols, and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

568. The system of claim 567, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

569. The system of claim 567, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

570. In a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for modulating bits on to subchannels to generate a plurality of DMT symbols, the system operable to enter a low power mode comprising:

means for receiving from a second transceiver a message comprising at least one parameter of a second bit allocation table for modulating bits on to at least one subchannel to be used for transmission at a second reduced data rate during the low power mode;

means for synchronizing use of the second bit allocation table between the transceiver and the second transceiver by transmitting a flag signal; and

means for seamlessly entering the low power mode by using the second bit allocation table for modulating bits on to subchannels to generate the plurality of DMT symbols and transmitting at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

571. The system of claim 570, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

572. The system of claim 570, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

573. In a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, the system operable to enter a low power mode comprising:

means for transmitting to a second transceiver a message comprising at least one parameter of a second bit allocation table for demodulating bits from at least one subchannel to be used for receiving at a second reduced data rate during the low power mode;

means for synchronizing use of the second bit allocation table between the transceiver and the second transceiver by receiving a flag signal; and

means for seamlessly entering the low power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols, and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the reception of the flag signal, wherein a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

574. The system of claim 573, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

575. The system of claim 573, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

576. In a multicarrier transceiver operating in a full power mode at a first data rate using a first bit allocation table for demodulating bits from subchannels in a plurality of DMT symbols, the system operable to enter a low power mode comprising:

means for transmitting to a second transceiver a message comprising at least one parameter of a second bit allocation table for demodulating bits from at least one subchannel to be used for receiving at a second reduced data rate during the low power mode;

means for synchronizing use of the second bit allocation table between the transceiver and the second transceiver by receiving a flag signal; and

means for seamlessly entering the low power mode by using the second bit allocation table for demodulating bits from subchannels in the plurality of DMT symbols, and receiving at the second data rate starting with a predetermined one of the DMT symbols that follows the transmission of the flag signal,

wherein a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the low power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the full power mode, and

the number of bits in a DMT symbol (N_BAT) for the low power mode is different than the number of bits in a DMT symbol (N_BAT) for the full power mode.

577. The system of claim 576, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

578. The system of claim 576, wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation.

579. In a multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the system operable to seamlessly enter a second power mode comprising:

means for storing a second bit allocation table to be used for transmitting codewords at a second bit rate in the second power mode;

means for synchronizing use of the second bit allocation table between the transmitter and a receiver; and

means for seamlessly entering the second power mode by using the second bit allocation table to transmit and receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit codewords in the first power mode are also used to transmit codewords in the second power mode, and a plurality of DMT symbols are decoupled from at least one of the plurality of codewords and a plurality of ADSL frames in at least one of the firs t and second power modes.

580. The system of claim 579, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

581. The system of claim 579, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

582. In a multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the system operable to seamlessly enter a second power mode comprising:

means for storing a second bit allocation table be used for transmitting codewords at a second bit rate in the second power mode;

means for synchronizing use of the second bit allocation table between the transmitter and a receiver; and

means for seamlessly entering the second power mode by using the second bit allocation table to transmit codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit codewords in the first power mode are also used to transmit codewords in the second power mode, and a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

583. The system of claim 582, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

584. The system of claim 582, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

585. In a multicarrier communication system transmitter using a first bit allocation table to transmit a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the system operable to seamlessly enter a second power mode comprising:

means for storing a second bit allocation table to be used for transmitting codewords at a second bit rate in the second power mode;

means for synchronizing use of the second bit allocation table between the transmitter and a receiver; and

means for seamlessly entering the second power mode by using the second bit allocation table to transmit codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode,

a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the first power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the second power mode, and

the number of bits in a DMT symbol (N_BAT) for the first power mode is different than the number of bits in a DMT symbol (N_BAT) for the second power mode.

586. The system of claim 585, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

587. The system of claim 585, wherein synchronizing includes transmitting a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

588. In a multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the system operable to seamlessly enter a second power mode comprising:

means for storing a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode;

means for synchronizing use of the second bit allocation table between the receiver and a transmitter; and

means for seamlessly entering the second power mode by using the second bit allocation table receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a plurality of DMT symbols are decoupled from at least one of the plurality of codewords and a plurality of ADSL frames in at least one of the first and second power modes.

589. The system of claim 588, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

590. The system of claim 588, wherein synchronizing includes receiving a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

591. In a multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the system operable to seamlessly enter a second power mode comprising:

means for storing a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode;

means for synchronizing use of the second bit allocation table between the receiver and a transmitter; and

means for seamlessly entering the second power mode by using the second bit allocation table to receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode, and a number of overhead framing bits in one DMT symbol is capable of being different than a number of overhead framing bits in another DMT symbol.

592. The system of claim 591, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

593. The system of claim 591, wherein synchronizing includes receiving a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.

594. In a multicarrier communication system receiver using a first bit allocation table to receive a plurality of codewords at a first bit rate in a first power mode, the plurality of codewords having a specified codeword size and including a specified number of parity bits for forward error correction, and a specified interleaving parameter for interleaving the plurality of codewords, the system operable to seamlessly enter a second power mode comprising:

means for storing a second bit allocation table to be used for receiving codewords at a second bit rate in the second power mode;

means for synchronizing use of the second bit allocation table between the receiver and transmitter; and

means for seamlessly entering the second power mode by using the second bit allocation table to receive codewords,

wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used to transmit and receive codewords in the first power mode are also used to transmit and receive codewords in the second power mode,

a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the first power mode is different than a ratio of the number of bits in a codeword (N_FEC) to the number of bits in a DMT symbol (N_BAT) for the second power mode, and

the number of bits in a DMT symbol (N_BAT) for the first power mode is different than the number of bits in a DMT symbol (N_BAT) for the second power mode.

595. The system of claim 594, wherein the bit allocation tables specify the number of bits modulated on to at least one subchannel and the fine gain values for at least one subchannel.

596. The system of claim 594, wherein synchronizing includes receiving a flag signal wherein the flag signal comprises at least one of a predefined signal, an inverted sync symbol, a sync symbol with a predefined phase shift, and a non-data carrying DMT symbol constructed by modulating subchannels with a predefined pseudo random bit sequence using QPSK modulation and wherein the transmitter transmits the flag signal to the receiver.