Seamless rate adaptive multicarrier modulation system and protocols

• US 6,498,808 B1
• Filed: 03/10/2000
• Issued: 12/24/2002
• 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): Kim, Kevin
• Application Number:
  US09/522,869
• Time in Patent Office: 1,019 Days
• Field of Search: 375/260, 375/225, 375/349, 375/222, 375/240.2, 370/538, 370/545
• US Class Current: 375/225
• 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. A method for seamlessly changing a transmission bit rate in a multicarrier communication system, the method comprising:

providing a plurality of codewords (i) having a specified codeword size, and (ii) including a specified number of parity bits for forward error correction;

providing a specified interleaving parameter for interleaving the plurality of codewords;

transmitting a first plurality of codewords at a first transmission bit rate; and

seamlessly transitioning to transmitting a second plurality of codewords at a second transmission bit rate, wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used for the first plurality of codewords are used for the second plurality of codewords and wherein transmitting at the first transmission bit rate comprises allocating a first number of bits specified by a first bit allocation table to a first DMT symbol and transmitting at the second transmission bit rate comprises allocating a second number of bits specified by a second bit allocation table to a second DMT symbol.

2. The method of claim 1 wherein an average parity bit ratio for DMT symbols transmitted at the first and the second transmission rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

18. 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.

3. A method for seamlessly changing a transmission bit rate in a multicarrier communication system, the method comprising:

providing a plurality of codewords having a plurality of codeword bits, the number of codeword bits determined by a specified codeword size, wherein a specified number of the codeword bits are parity bits for forward error correction;

allocating the plurality of codeword bits of a first plurality of codewords to at least one of a plurality of carrier subchannels using a first bit allocation table for transmitting the first plurality of codewords at a first transmission bit rate;

transmitting the first plurality of codewords at the first transmission bit rate;

allocating the plurality of codeword bits of a second plurality of codewords to at least one of the plurality of carrier subchannels using a second bit allocation table for transmitting the second plurality of codewords at a second transmission bit rate; and

seamlessly transitioning from the first transmission bit rate to the second transmission bit rate by transmitting the second plurality of codewords, wherein the specified codeword size and the specified number of parity bits for forward error correction used when transmitting each of the first plurality of codewords are used when transmitting each of the second plurality of codewords.

4. The method of claim 3 further comprising interleaving the first plurality and the second plurality of codewords according to a specified interleaving parameter, wherein the specified interleaving parameter used to interleave the first plurality of codewords is the same specified interleaving parameter used to interleave the second plurality of codewords.

5. The method of claim 3 wherein transmitting at the first transmission bit rate comprises allocating a first number of the codeword bits to a first DMT symbol as determined by the first bit allocation table;

and wherein transmitting at the second transmission bit rate comprises allocating a second number of the codeword bits to a second DMT symbol as determined by the second bit allocation table.

6. The method of claim 5 wherein an average parity bit ratio for DMT symbols transmitted at the first and the second transmission rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

19. The method of claim 3, 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.

7. A method for seamlessly changing a reception bit rate in a multicarrier communication system, the method comprising:

receiving a first plurality of codewords from at least one of a plurality of carrier subchannels at a first reception bit rate, the plurality of codewords having a plurality of codeword bits, the number of codeword bits determined by a specified codeword size, wherein a specified number of the codeword bits are parity bits for forward error correction;

demodulating the plurality of codeword bits of the first plurality of codewords using a first bit allocation table;

seamlessly transitioning from the first reception bit rate to a second reception bit rate;

receiving a second plurality of codewords from at least one of the plurality of carrier subchannels at the second reception bit rate;

demodulating the plurality of codeword bits of the second plurality of codewords using a second bit allocation table,

wherein the specified codeword size, and the specified number of parity bits for forward error correction used when demodulating each of the first plurality of codewords is used when demodulating each of the second plurality of codewords.

8. The method of claim 7 further comprising deinterleaving the first plurality and the second plurality of codewords according to a specified deinterleaving parameter, wherein the specified deinterleaving parameter used to deinterleave the first plurality of codewords is the same specified deinterleaving parameter used to deinterleave the second plurality of codewords.

9. The method of claim 7 wherein an average parity bit ratio for DMT symbols received at the first and the second reception rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

20. The method of claim 7, 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.

10. A method for seamlessly changing a reception bit rate in a multicarrier communication system, the method comprising:

providing a specified deinterleaving parameter;

receiving a first plurality of codewords at a first reception bit rate, the plurality of codewords (i) having a specified codeword size, and (ii) including a specified number of parity bits for forward error correction; and

seamlessly transitioning to receiving a second plurality of codewords at a second reception bit rate, wherein the specified deinterleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used for the first plurality of codewords are used for the second plurality of codewords and wherein receiving at the first reception bit rate comprises demodulating a first number of bits of a first DMT symbol as determined by a first bit allocation table and receiving at the second reception bit rate comprises demodulating a second number of bits of a second DMT symbol as determined by a second bit allocation table.

11. The method of claim 10 wherein an average parity bit ratio for DMT symbols received at the first and the second reception rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

21. The method of claim 10, 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.

12. A transmitter in a multicarrier communication system for seamlessly changing a transmission bit rate, comprising:

an encoder producing a plurality of codewords having a plurality of codeword bits, the number of codeword bits determined by a specified codeword size, wherein a specified number of codeword bits are parity bits for forward error correction;

an interleaver in communication with the encoder, the interleaver interleaving the plurality of codewords according to a specified interleaving parameter; and

a modulator in communication with the interleaver, the modulator allocating the plurality of codeword bits of each interleaved codeword to at least one of a plurality of carrier subchannels to achieve transmission at a first transmission bit rate and seamlessly changing the bit allocation to achieve transmission at a second transmission bit rate, wherein the specified interleaving parameter, specified codeword size, and the specified number of parity bits for forward error correction remain unchanged after the modulator changes the allocation of bits to achieve transmission at the second transmission bit rate.

13. The transmitter of claim 12, wherein the modulator transmits a first DMT symbol having a first number of the codeword bits, determined by a first bit allocation table, at the first transmission bit rate;

and a second DMT symbol having a second number of the codeword bits, determined by a second bit allocation table, at the second transmission rate.

14. The transmitter of claim 13 wherein the modulator transmits a first DMT symbol at the first transmission bit rate and a second DMT symbol at the second transmission rate, and wherein an average parity bit ratio for DMT symbols transmitted at the first and the second transmission rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

22. The system of claim 13, 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.

15. A receiver in a multicarrier communication system for seamlessly changing a reception bit rate, the receiver comprising:

a demodulator operating at a first reception bit rate to produce a first plurality of interleaved codewords and seamlessly changing operation to a second reception bit rate to produce a second plurality of interleaved codewords, each codeword having a specified codeword size and including a specified number of parity bits for error correction;

a deinterleaver in communication with the demodulator, the deinterleaver deinterleaving the first and the second plurality of interleaved codewords according to a specified interleaving parameter;

a decoder in communication with the demodulator to receive and decode the first and the second plurality of deinterleaved codewords, wherein the specified interleaving parameter used to deinterleave the first plurality of interleaved codewords is the same specified interleaving parameter used to deinterleave the second plurality of interleaved codewords, and the specified codeword size and the specified number of parity bits for error correction used to decode the first plurality of deinterleaved codewords are the same specified codeword size and specified number of parity bits for error correction used to decode the second plurality of deinterleaved codewords and wherein the demodulator receives a first DMT symbol at the first reception bit rate and a second DMT symbol at the second reception bit rate, the first DMT symbol having a first number of bits determined by a first bit allocation table and the second DMT symbol having a second number of bits determined by a second bit allocation table.

16. The receiver of claim 15 wherein an average parity bit ratio for DMT symbols received by the demodulator at the first and the second reception rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

23. The system of claim 15, 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.

17. A method for seamlessly changing a reception bit rate in a multicarrier communication system, the method comprising:

receiving a first plurality of codewords at a first reception bit rate using a first bit allocation table the plurality of codewords (i) having a specified codeword size, and (ii) including a specified number of parity bits for forward error correction;

seamlessly changing from the first reception bit rate to a second reception bit rate using a second bit allocation table; and

receiving a second plurality of codewords at the second reception bit rate, wherein the specified codeword size and the specified number of parity bits for forward error correction used for the first plurality of codewords are used for the second plurality of codewords and the number of bits in the first bit allocation table is different than the number of bits in the second bit allocation table.

24. The method of claim 17, 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.

25. A system that seamlessly changes a transmission bit rate in a multicarrier communication system comprising:

an encoder that provides a plurality of codewords (i) having a specified codeword size, and (ii) including a specified number of parity bits for forward error correction;

an interleaver that provides a specified interleaving parameter for interleaving the plurality of codewords;

a transmitter that transmits a first plurality of codewords at a first transmission bit rate and seamlessly transitions to transmitting a second plurality of codewords at a second transmission bit rate, wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used for the first plurality of codewords are used for the second plurality of codewords; and

a modulator that allocates a first number of bits specified by a first bit allocation table to a first DMT symbol for transmission at the first transmission bit rate, and allocates a second number of bits specified by a second bit allocation table to a second DMT symbol for transmission at the second transmission bit rate.

26. The system of claim 25, 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.

27. The system of claim 25, wherein an average parity bit ratio for DMT symbols transmitted at the first and the second transmission rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

28. A system that seamlessly changes a transmission bit rate in a multicarrier communication system comprising:

an encoder that provides a plurality of codewords having a plurality of codeword bits, the number of codeword bits determined by a specified codeword size, wherein a specified number of the codeword bits are parity bits for forward error correction;

a modulator that allocates the plurality of codeword bits of a first plurality of codewords to at least one of a plurality of carrier subchannels using a first bit allocation table for transmitting the first plurality of codewords at a first transmission bit rate, and the plurality of codeword bits of a second plurality of codewords to at least one of the plurality of carrier subchannels using a second bit allocation table for transmitting the second plurality of codewords at a second transmission bit rate; and

a transmitter that transmits the first plurality of codewords at the first transmission bit rate and seamlessly transitions from the first transmission bit rate to the second transmission bit rate by transmitting the second plurality of codewords, wherein the specified codeword size and the specified number of parity bits for forward error correction used when transmitting each of the first plurality of codewords are used when transmitting each of the second plurality of codewords.

29. The system of claim 28, further comprising an interleaver that interleaves the first plurality and the second plurality of codewords according to a specified interleaving parameter, wherein the specified interleaving parameter used to interleave the first plurality of codewords is the same specified interleaving parameter used to interleave the second plurality of codewords.

30. The system of claim 28, wherein the transmitter transmits at the first transmission bit rate by allocating a first number of the codeword bits to a first DMT symbol as determined by the first bit allocation table, and transmits at the second transmission bit rate by allocating a second number of the codeword bits to a second DMT symbol as determined by the second bit allocation table.

31. The system of claim 30, wherein an average parity bit ratio for DMT symbols transmitted at the first and the second transmission rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

32. The system of claim 28, 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.

33. A system that seamlessly changes a reception bit rate in a multicarrier communication system comprising:

a receiver that receives a first plurality of codewords from at least one of a plurality of carrier subchannels at a first reception bit rate, the plurality of codewords having a plurality of codeword bits, the number of codeword bits determined by a specified codeword size, wherein a specified number of the codeword bits are parity bits for forward error correction, and seamlessly transitions from the first reception bit rate to a second reception bit rate to receive a second plurality of codewords from at least one of the plurality of carrier subchannels at the second reception bit rate; and

a demodulator that demodulates the plurality of codeword bits of the first plurality of codewords using a first bit allocation table and the plurality of codeword bits of the second plurality of codewords using a second bit allocation table,

wherein the specified codeword size, and the specified number of parity bits for forward error correction used when demodulating each of the first plurality of codewords is used when demodulating each of the second plurality of codewords.

34. The system of claim 33, further comprising a deinterleaver that deinterleaves the first plurality and the second plurality of codewords according to a specified deinterleaving parameter, wherein the specified deinterleaving parameter used to deinterleave the first plurality of codewords is the same specified deinterleaving parameter used to deinterleave the second plurality of codewords.

35. The system of claim 33, wherein an average parity bit ratio for DMT symbols received at the first and the second reception rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

36. The system of claim 33, 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.

37. A system that seamlessly changes a reception bit rate in a multicarrier communication system comprising:

a deinterleaver that determines a specified deinterleaving parameter;

a receiver that receives a first plurality of codewords at a first reception bit rate, the plurality of codewords (i) having a specified codeword size, and (ii) including a specified number of parity bits for forward error correction, the receiver seamlessly transitioning to receiving a second plurality of codewords at a second reception bit rate, wherein the specified deinterleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used for the first plurality of codewords are used for the second plurality of codewords; and

a demodulator that demodulates a first number of bits of a first DMT symbol as determined by a first bit allocation table and a second number of bits of a second DMT symbol as determined by a second bit allocation table.

38. The system of claim 37, wherein an average parity bit ratio for DMT symbols received at the first and the second reception rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

39. The system 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.

40. A method for multicarrier communication that seamlessly changes a transmission bit rate comprising:

producing a plurality of codewords having a plurality of codeword bits, the number of codeword bits determined by a specified codeword size, wherein a specified number of codeword bits are parity bits for forward error correction;

interleaving the plurality of codewords according to a specified interleaving parameter; and

allocating the plurality of codeword bits of each interleaved codeword to at least one of a plurality of carrier subchannels to achieve transmission at a first transmission bit rate and seamlessly changing the bit allocation to achieve transmission at a second transmission bit rate, wherein the specified interleaving parameter, specified codeword size, and the specified number of parity bits for forward error correction remain unchanged after the modulator changes the allocation of bits to achieve transmission at the second transmission bit rate.

41. The method of claim 40, further comprising transmitting a first DMT symbol having a first number of the codeword bits, determined by a first bit allocation table, at the first transmission bit rate;

and

transmitting a second DMT symbol having a second number of the codeword bits, determined by a second bit allocation table, at the second transmission rate.

42. The method of claim 41, further comprising transmitting a first DMT symbol at the first transmission bit rate and a second DMT symbol at the second transmission rate, wherein an average parity bit ratio for DMT symbols transmitted at the first and the second transmission rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

43. The method of claim 41, 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.

44. A method for multicarrier communication that seamlessly changes a reception bit rate comprising:

producing a first plurality of interleaved codewords;

seamlessly changing operation to a second reception bit rate to produce a second plurality of interleaved codewords, each codeword having a specified codeword size and including a specified number of parity bits for error correction;

deinterleaving the first and the second plurality of interleaved codewords according to a specified interleaving parameter;

decoding the first and the second plurality of deinterleaved codewords, wherein the specified interleaving parameter used to deinterleave the first plurality of interleaved codewords is the same specified interleaving parameter used to deinterleave the second plurality of interleaved codewords, and the specified codeword size and the specified number of parity bits for error correction used to decode the first plurality of deinterleaved codewords are the same specified codeword size and specified number of parity bits for error correction used to decode the second plurality of deinterleaved codewords; and

receiving a first DMT symbol at the first reception bit rate and a second DMT symbol at the second reception bit rate, the first DMT symbol having a first number of bits determined by a first bit allocation table and the second DMT symbol having a second number of bits determined by a second bit allocation table.

45. The method of claim 44, wherein an average parity bit ratio for DMT symbols received by the demodulator at the first and the second reception rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

46. The method of claim 44, 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.

47. A multicarrier communication system that seamlessly changes a reception bit rate comprising:

a first plurality of codewords that are received at a first reception bit rate using a first bit allocation table, the plurality of codewords (i) having a specified codeword size, and (ii) including a specified number of parity bits for forward error correction; and

a receiver that seamlessly changes from the first reception bit rate to a second reception bit rate using a second bit allocation table to receive a second plurality of codewords at the second reception bit rate, wherein the specified codeword size and the specified number of parity bits for forward error correction used for the first plurality of codewords are used for the second plurality of codewords and the number of bits in the first bit allocation table is different than the number of bits in the second bit allocation table.

48. The system of claim 47, 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.

49. An information storage media comprising information that seamlessly changes a transmission bit rate in a multicarrier communication system comprising:

information that provides a plurality of codewords (i) having a specified codeword size, and (ii) including a specified number of parity bits for forward error correction;

information that provides a specified interleaving parameter for interleaving the plurality of codewords;

information that transmits a first plurality of codewords at a first transmission bit rate and seamlessly transitions to transmitting a second plurality of codewords at a second transmission bit rate, wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used for the first plurality of codewords are used for the second plurality of codewords; and

information that allocates a first number of bits specified by a first bit allocation table to a first DMT symbol for transmission at the first transmission bit rate, and allocates a second number of bits specified by a second bit allocation table to a second DMT symbol for transmission at the second transmission bit rate.

50. The media of claim 49, 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.

51. The media of claim 49, wherein an average parity bit ratio for DMT symbols transmitted at the first and the second transmission rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

52. An information storage media comprising information that seamlessly changes a transmission bit rate in a multicarrier communication system comprising:

information that provides a plurality of codewords having a plurality of codeword bits, the number of codeword bits determined by a specified codeword size, wherein a specified number of the codeword bits are parity bits for forward error correction;

information that allocates the plurality of codeword bits of a first plurality of codewords to at least one of a plurality of carrier subchannels using a first bit allocation table for transmitting the first plurality of codewords at a first transmission bit rate, and the plurality of codeword bits of a second plurality of codewords to at least one of the plurality of carrier subchannels using a second bit allocation table for transmitting the second plurality of codewords at a second transmission bit rate; and

information that transmits the first plurality of codewords at the first transmission bit rate and seamlessly transitions from the first transmission bit rate to the second transmission bit rate by transmitting the second plurality of codewords, wherein the specified codeword size and the specified number of parity bits for forward error correction used when transmitting each of the first plurality of codewords are used when transmitting each of the second plurality of codewords.

53. The media of claim 52, further comprising information that interleaves the first plurality and the second plurality of codewords according to a specified interleaving parameter, wherein the specified interleaving parameter used to interleave the first plurality of codewords is the same specified interleaving parameter used to interleave the second plurality of codewords.

54. The media of claim 52, wherein the information transmits at the first transmission bit rate by allocating a first number of the codeword bits to a first DMT symbol as determined by the first bit allocation table, and transmits at the second transmission bit rate by allocating a second number of the codeword bits to a second DMT symbol as determined by the second bit allocation table.

55. The media of claim 54, wherein an average parity bit ratio for DMT symbols transmitted at the first and the second transmission rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

56. The media of claim 52, 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.

57. An information storage media comprising information that seamlessly changes a reception bit rate in a multicarrier communication system comprising:

information that receives a first plurality of codewords from at least one of a plurality of carrier subchannels at a first reception bit rate, the plurality of codewords having a plurality of codeword bits, the number of codeword bits determined by a specified codeword size, wherein a specified number of the codeword bits are parity bits for forward error correction, and seamlessly transitions from the first reception bit rate to a second reception bit rate to receive a second plurality of codewords from at least one of the plurality of carrier subchannels at the second reception bit rate; and

information that demodulates the plurality of codeword bits of the first plurality of codewords using a first bit allocation table and the plurality of codeword bits of the second plurality of codewords using a second bit allocation table,

wherein the specified codeword size, and the specified number of parity bits for forward error correction used when demodulating each of the first plurality of codewords is used when demodulating each of the second plurality of codewords.

58. The media of claim 57, further comprising information that deinterleaves the first plurality and the second plurality of codewords according to a specified deinterleaving parameter, wherein the specified deinterleaving parameter used to deinterleave the first plurality of codewords is the same specified deinterleaving parameter used to deinterleave the second plurality of codewords.

59. The media of claim 57, wherein an average parity bit ratio for DMT symbols received at the first and the second reception rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

60. The media 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.

61. An information storage media comprising information that seamlessly changes a reception bit rate in a multicarrier communication system comprising:

information that determines a specified deinterleaving parameter;

information that receives a first plurality of codewords at a first reception bit rate, the plurality of codewords (i) having a specified codeword size, and (ii) including a specified number of parity bits for forward error correction, and seamlessly transitions to receiving a second plurality of codewords at a second reception bit rate, wherein the specified deinterleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used for the first plurality of codewords are used for the second plurality of codewords; and

information that demodulates a first number of bits of a first DMT symbol as determined by a first bit allocation table and a second number of bits of a second DMT symbol as determined by a second bit allocation table.

62. The media of claim 61, wherein an average parity bit ratio for DMT symbols received at the first and the second reception rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

63. The media of claim 61, 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.

64. An information storage media comprising information for seamlessly changing a transmission bit rate in a multicarrier communication system comprising:

information that produces a plurality of codewords having a plurality of codeword bits, the number of codeword bits determined by a specified codeword size, wherein a specified number of codeword bits are parity bits for forward error correction;

information that interleaves the plurality of codewords according to a specified interleaving parameter; and

information that allocates the plurality of codeword bits of each interleaved codeword to at least one of a plurality of carrier subchannels to achieve transmission at a first transmission bit rate and seamlessly changes the bit allocation to achieve transmission at a second transmission bit rate, wherein the specified interleaving parameter, specified codeword size, and the specified number of parity bits for forward error correction remain unchanged after the modulator changes the allocation of bits to achieve transmission at the second transmission bit rate.

65. The media of claim 64, wherein the information transmits a first DMT symbol having a first number of the codeword bits, determined by a first bit allocation table, at the first transmission bit rate;

and a second DMT symbol having a second number of the codeword bits, determined by a second bit allocation table, at the second transmission rate.

66. The media of claim 65, wherein the information transmits a first DMT symbol at the first transmission bit rate and a second DMT symbol at the second transmission rate, and wherein an average parity bit ratio for DMT symbols transmitted at the first and the second transmission rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

67. The media of claim 65, 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.

68. An information storage media comprising information for seamlessly changing a reception bit rate in a multicarrier communication system comprising:

information that operates at a first reception bit rate to produce a first plurality of interleaved codewords and seamlessly changes operation to a second reception bit rate to produce a second plurality of interleaved codewords, each codeword having a specified codeword size and including a specified number of parity bits for error correction;

information that deinterleaves the first and the second plurality of interleaved codewords according to a specified interleaving parameter; and

information that receives and decodes the first and the second plurality of deinterleaved codewords, wherein the specified interleaving parameter used to deinterleave the first plurality of interleaved codewords is the same specified interleaving parameter used to deinterleave the second plurality of interleaved codewords, the specified codeword size and the specified number of parity bits for error correction used to decode the first plurality of deinterleaved codewords are the same specified codeword size and specified number of parity bits for error correction used to decode the second plurality of deinterleaved codewords, and

a receiver receives a first DMT symbol at the first reception bit rate and a second DMT symbol at the second reception bit rate, the first DMT symbol having a first number of bits determined by a first bit allocation table and the second DMT symbol having a second number of bits determined by a second bit allocation table.

69. The media of claim 68, wherein an average parity bit ratio for DMT symbols received by a demodulator at the first and the second reception rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

70. The media of claim 68, 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. An information storage media that seamlessly changes a reception bit rate in a multicarrier communication system comprising:

information that receives a first plurality of codewords at a first reception bit rate using a first bit allocation table, the plurality of codewords (i) having a specified codeword size, and (ii) including a specified number of parity bits for forward error correction; and

information that seamlessly changes from the first reception bit rate to a second reception bit rate using a second bit allocation table to receive a second plurality of codewords at the second reception bit rate, wherein the specified codeword size and the specified number of parity bits for forward error correction used for the first plurality of codewords are used for the second plurality of codewords and the number of bits in the first bit allocation table is different than the number of bits in the second bit allocation table.

72. The media of claim 71, 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.

73. A multicarrier communication system that seamlessly changes a transmission bit rate in a multicarrier communication system comprising:

means for providing a plurality of codewords (i) having a specified codeword size, and (ii) including a specified number of parity bits for forward error correction;

means for providing a specified interleaving parameter for interleaving the plurality of codewords;

means for transmitting a first plurality of codewords at a first transmission bit rate and seamlessly transitioning to transmitting a second plurality of codewords at a second transmission bit rate, wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used for the first plurality of codewords are used for the second plurality of codewords; and

means for allocating a first number of bits specified by a first bit allocation table to a first DMT symbol for transmission at the first transmission bit rate, and allocating a second number of bits specified by a second bit allocation table to a second DMT symbol for transmission at the second transmission bit rate.

74. The system of claim 73, 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.

75. The system of claim 73, wherein an average parity bit ratio for DMT symbols transmitted at the first and the second transmission rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

76. A multicarrier communication system that seamlessly changes a transmission bit rate comprising:

means for providing a plurality of codewords having a plurality of codeword bits, the number of codeword bits determined by a specified codeword size, wherein a specified number of the codeword bits are parity bits for forward error correction;

means for allocating the plurality of codeword bits of a first plurality of codewords to at least one of a plurality of carrier subchannels using a first bit allocation table for transmitting the first plurality of codewords at a first transmission bit rate, and the plurality of codeword bits of a second plurality of codewords to at least one of the plurality of carrier subchannels using a second bit allocation table for transmitting the second plurality of codewords at a second transmission bit rate; and

means for transmitting the first plurality of codewords at the first transmission bit rate and seamlessly transitioning from the first transmission bit rate to the second transmission bit rate by transmitting the second plurality of codewords, wherein the specified codeword size and the specified number of parity bits for forward error correction used when transmitting each of the first plurality of codewords are used when transmitting each of the second plurality of codewords.

77. The system of claim 76, further comprising means for interleaving the first plurality and the second plurality of codewords according to a specified interleaving parameter, wherein the specified interleaving parameter used to interleave the first plurality of codewords is the same specified interleaving parameter used to interleave the second plurality of codewords.

78. The system of claim 76, wherein the means for transmitting transmits at the first transmission bit rate by allocating a first number of the codeword bits to a first DMT symbol as determined by the first bit allocation table, and transmits at the second transmission bit rate by allocating a second number of the codeword bits to a second DMT symbol as determined by the second bit allocation table.

79. The system of claim 78, wherein an average parity bit ratio for DMT symbols transmitted at the first and the second transmission rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

80. The system of claim 76, 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.

81. A multicarrier communication system seamlessly changes a reception bit rate comprising:

means for receiving a first plurality of codewords from at least one of a plurality of carrier subchannels at a first reception bit rate, the plurality of codewords having a plurality of codeword bits, the number of codeword bits determined by a specified codeword size, wherein a specified number of the codeword bits are parity bits for forward error correction, and seamlessly transitions from the first reception bit rate to a second reception bit rate to receive a second plurality of codewords from at least one of the plurality of carrier subchannels at the second reception bit rate; and

means for demodulating the plurality of codeword bits of the first plurality of codewords using a first bit allocation table and the plurality of codeword bits of the second plurality of codewords using a second bit allocation table,

wherein the specified codeword size, and the specified number of parity bits for forward error correction used when demodulating each of the first plurality of codewords is used when demodulating each of the second plurality of codewords.

82. The system of claim 81, further comprising means for deinterleaving the first plurality and the second plurality of codewords according to a specified deinterleaving parameter, wherein the specified deinterleaving parameter used to deinterleave the first plurality of codewords is the same specified deinterleaving parameter used to deinterleave the second plurality of codewords.

83. The system of claim 81, wherein an average parity bit ratio for DMT symbols received at the first and the second reception rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

84. The system of claim 81, 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.

85. A multicarrier communication system that seamlessly changes a reception bit rate comprising:

means for determining a specified deinterleaving parameter;

means for receiving a first plurality of codewords at a first reception bit rate, the plurality of codewords (i) having a specified codeword size, and (ii) including a specified number of parity bits for forward error correction, and seamlessly transitioning to receiving a second plurality of codewords at a second reception bit rate, wherein the specified deinterleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used for the first plurality of codewords are used for the second plurality of codewords; and

means for demodulating a first number of bits of a first DMT symbol as determined by a first bit allocation table and a second number of bits of a second DMT symbol as determined by a second bit allocation table.

86. The system of claim 85, wherein an average parity bit ratio for DMT symbols received at the first and the second reception rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

87. The system of claim 85, 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.

88. A multicarrier communication system that seamlessly changes a transmission bit rate comprising:

means for producing a plurality of codewords having a plurality of codeword bits, the number of codeword bits determined by a specified codeword size, wherein a specified number of codeword bits are parity bits for forward error correction;

means for interleaving the plurality of codewords according to a specified interleaving parameter; and

means for allocating the plurality of codeword bits of each interleaved codeword to at least one of a plurality of carrier subchannels to achieve transmission at a first transmission bit rate and seamlessly changes the bit allocation to achieve transmission at a second transmission bit rate, wherein the specified interleaving parameter, specified codeword size, and the specified number of parity bits for forward error correction remain unchanged after the modulator changes the allocation of bits to achieve transmission at the second transmission bit rate.

89. The system of claim 88, wherein the means for allocating transmits a first DMT symbol having a first number of the codeword bits, determined by a first bit allocation table, at the first transmission bit rate;

and a second DMT symbol having a second number of the codeword bits, determined by a second bit allocation table, at the second transmission rate.

90. The system of claim 89, wherein the means for allocating transmits a first DMT symbol at the first transmission bit rate and a second DMT symbol at the second transmission rate, and wherein an average parity bit ratio for DMT symbols transmitted at the first and the second transmission rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

91. The system of claim 89, 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.

92. A multicarrier communication system that seamlessly changes a reception bit rate comprising:

means for operating at a first reception bit rate to produce a first plurality of interleaved codewords and seamlessly changing operation to a second reception bit rate to produce a second plurality of interleaved codewords, each codeword having a specified codeword size and including a specified number of parity bits for error correction;

means for deinterleaving the first and the second plurality of interleaved codewords according to a specified interleaving parameter; and

means for receiving and decoding the first and the second plurality of deinterleaved codewords, wherein the specified interleaving parameter used to deinterleave the first plurality of interleaved codewords is the same specified interleaving parameter used to deinterleave the second plurality of interleaved codewords, and the specified codeword size and the specified number of parity bits for error correction used to decode the first plurality of deinterleaved codewords are the same specified codeword size and specified number of parity bits for error correction used to decode the second plurality of deinterleaved codewords, and

the receiving means receives a first DMT symbol at the first reception bit rate and a second DMT symbol at the second reception bit rate, the first DMT symbol having a first number of bits determined by a first bit allocation table and the second DMT symbol having a second number of bits determined by a second bit allocation table.

93. The system of claim 92, wherein an average parity bit ratio for DMT symbols received by a demodulator at the first and the second reception rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

94. The system of claim 92, 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.

95. A multicarrier communication system that seamlessly changes a reception bit rate comprising:

means for receiving a first plurality of codewords at a first reception bit rate using a first bit allocation table, the plurality of codewords (i) having a specified codeword size, and (ii) including a specified number of parity bits for forward error correction; and

means for seamlessly changing from the first reception bit rate to a second reception bit rate using a second bit allocation table to receive a second plurality of codewords at the second reception bit rate, wherein the specified codeword size and the specified number of parity bits for forward error correction used for the first plurality of codewords are used for the second plurality of codewords and the number of bits in the first bit allocation table is different than the number of bits in the second bit allocation table.

96. The system 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.

97. A communication protocol that seamlessly changes a transmission bit rate in a multicarrier communication system comprising:

providing a plurality of codewords (i) having a specified codeword size, and (ii) including a specified number of parity bits for forward error correction;

providing a specified interleaving parameter for interleaving the plurality of codewords;

transmitting a first plurality of codewords at a first transmission bit rate and seamlessly transitioning to transmitting a second plurality of codewords at a second transmission bit rate, wherein the specified interleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used for the first plurality of codewords are used for the second plurality of codewords; and

allocating a first number of bits specified by a first bit allocation table to a first DMT symbol for transmission at the first transmission bit rate, and allocating a second number of bits specified by a second bit allocation table to a second DMT symbol for transmission at the second transmission bit rate.

98. The protocol of claim 97, 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 protocol of claim 97, wherein an average parity bit ratio for DMT symbols transmitted at the first and the second transmission rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

100. A communications protocol that seamlessly changes a transmission bit rate in a multicarrier communication system comprising:

providing a plurality of codewords having a plurality of codeword bits, the number of codeword bits determined by a specified codeword size, wherein a specified number of the codeword bits are parity bits for forward error correction;

allocating the plurality of codeword bits of a first plurality of codewords to at least one of a plurality of carrier subchannels using a first bit allocation table for transmitting the first plurality of codewords at a first transmission bit rate, and the plurality of codeword bits of a second plurality of codewords to at least one of the plurality of carrier subchannels using a second bit allocation table for transmitting the second plurality of codewords at a second transmission bit rate; and

transmitting the first plurality of codewords at the first transmission bit rate and seamlessly transitions from the first transmission bit rate to the second transmission bit rate by transmitting the second plurality of codewords, wherein the specified codeword size and the specified number of parity bits for forward error correction used when transmitting each of the first plurality of codewords are used when transmitting each of the second plurality of codewords.

101. The protocol of claim 100, further comprising interleaving the first plurality and the second plurality of codewords according to a specified interleaving parameter, wherein the specified interleaving parameter used to interleave the first plurality of codewords is the same specified interleaving parameter used to interleave the second plurality of codewords.

102. The protocol of claim 100, wherein transmitting at the first transmission bit rate comprises allocating a first number of the codeword bits to a first DMT symbol as determined by the first bit allocation table, and transmitting at the second transmission bit rate by allocating a second number of the codeword bits to a second DMT symbol as determined by the second bit allocation table.

103. The protocol of claim 102, wherein an average parity bit ratio for DMT symbols transmitted at the first and the second transmission rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

104. The protocol 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.

105. A communications protocol that seamlessly changes a reception bit rate in a multicarrier communication system comprising:

receiving a first plurality of codewords from at least one of a plurality of carrier subchannels at a first reception bit rate, the plurality of codewords having a plurality of codeword bits, the number of codeword bits determined by a specified codeword size, wherein a specified number of the codeword bits are parity bits for forward error correction, and seamlessly transitions from the first reception bit rate to a second reception bit rate to receive a second plurality of codewords from at least one of the plurality of carrier subchannels at the second reception bit rate; and

demodulating the plurality of codeword bits of the first plurality of codewords using a first bit allocation table and the plurality of codeword bits of the second plurality of codewords using a second bit allocation table,

wherein the specified codeword size, and the specified number of parity bits for forward error correction used when demodulating each of the first plurality of codewords is used when demodulating each of the second plurality of codewords.

106. The protocol of claim 105, further comprising deinterleaving the first plurality and the second plurality of codewords according to a specified deinterleaving parameter, wherein the specified deinterleaving parameter used to deinterleave the first plurality of codewords is the same specified deinterleaving parameter used to deinterleave the second plurality of codewords.

107. The protocol of claim 105, wherein an average parity bit ratio for DMT symbols received at the first and the second reception rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

108. The protocol 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. A communications protocol that seamlessly changes a reception bit rate in a multicarrier communication system comprising:

determining a specified deinterleaving parameter;

receiving a first plurality of codewords at a first reception bit rate, the plurality of codewords (i) having a specified codeword size, and (ii) including a specified number of parity bits for forward error correction, and seamlessly transitioning to receiving a second plurality of codewords at a second reception bit rate, wherein the specified deinterleaving parameter, the specified codeword size, and the specified number of parity bits for forward error correction used for the first plurality of codewords are used for the second plurality of codewords; and

demodulating a first number of bits of a first DMT symbol as determined by a first bit allocation table and a second number of bits of a second DMT symbol as determined by a second bit allocation table.

110. The protocol of claim 109, wherein an average parity bit ratio for DMT symbols received at the first and the second reception rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

111. The protocol of claim 109, 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.

112. A communications protocol that seamlessly changes a transmission bit rate in a multicarrier communication system comprising:

producing a plurality of codewords having a plurality of codeword bits, the number of codeword bits determined by a specified codeword size, wherein a specified number of codeword bits are parity bits for forward error correction;

interleaving the plurality of codewords according to a specified interleaving parameter; and

allocating the plurality of codeword bits of each interleaved codeword to at least one of a plurality of carrier subchannels to achieve transmission at a first transmission bit rate and seamlessly changes the bit allocation to achieve transmission at a second transmission bit rate, wherein the specified interleaving parameter, specified codeword size, and the specified number of parity bits for forward error correction remain unchanged after the modulator changes the allocation of bits to achieve transmission at the second transmission bit rate.

113. The protocol of claim 112, further comprising transmitting a first DMT symbol having a first number of the codeword bits, determined by a first bit allocation table, at the first transmission bit rate;

and a second DMT symbol having a second number of the codeword bits, determined by a second bit allocation table, at the second transmission rate.

114. The protocol of claim 113, further comprising transmitting a first DMT symbol at the first transmission bit rate and a second DMT symbol at the second transmission rate, and wherein an average parity bit ratio for DMT symbols transmitted at the first and the second transmission rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

115. The protocol of claim 113, 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.

116. A communications protocol that seamlessly changes a reception bit rate in a multicarrier communication system comprising:

operating at a first reception bit rate to produce a first plurality of interleaved codewords and seamlessly changing to operating at a second reception bit rate to produce a second plurality of interleaved codewords, each codeword having a specified codeword size and including a specified number of parity bits for error correction;

deinterleaving the first and the second plurality of interleaved codewords according to a specified interleaving parameter; and

receiving and decoding the first and the second plurality of deinterleaved codewords, wherein the specified interleaving parameter used to deinterleave the first plurality of interleaved codewords is the same specified interleaving parameter used to deinterleave the second plurality of interleaved codewords, and the specified codeword size and the specified number of parity bits for error correction used to decode the first plurality of deinterleaved codewords are the same specified codeword size and specified number of parity bits for error correction used to decode the second plurality of deinterleaved codewords, and a receiver receives a first DMT symbol at the first reception bit rate and a second DMT symbol at the second reception bit rate, the first DMT symbol having a first number of bits determined by a first bit allocation table and the second DMT symbol having a second number of bits determined by a second bit allocation table.

117. The protocol of claim 116, wherein an average parity bit ratio for DMT symbols received by a demodulator at the first and the second reception rates is substantially constant, where a parity bit ratio is the number of parity bits in a DMT symbol divided by the total number of bits in the bit allocation table used for that DMT symbol.

118. The protocol of claim 116, 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.

119. A communications protocol that seamlessly changes a reception bit rate in a multicarrier communication system comprising:

receiving a first plurality of codewords at a first reception bit rate using a first bit allocation table, the plurality of codewords (i) having a specified codeword size, and (ii) including a specified number of parity bits for forward error correction; and

seamlessly changing from the first reception bit rate to a second reception bit rate using a second bit allocation table to receive a second plurality of codewords at the second reception bit rate, wherein the specified codeword size and the specified number of parity bits for forward error correction used for the first plurality of codewords are used for the second plurality of codewords and the number of bits in the first bit allocation table is different than the number of bits in the second bit allocation table.

120. The protocol of claim 119, 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.