Cable modem with voice processing capability

• US 20020061012A1
• Filed: 09/12/2001
• Published: 05/23/2002
• Est. Priority Date: 04/13/1999
• Status: Active Grant

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Miller, Kevin L., Lee, Robert J., Lukas, Robert M., Unger, Kenneth J., Borazjani, Ramin, Hartman, David, Brooks, Todd L., Lansing, Shane P., Rabenko, Theodore F., Thi, James C.
• Granted Patent: US 7,933,295 B2
• Time in Patent Office: Days
• US Class Current: 370/352
• CPC Class Codes: H04B 3/23 using a replica of transmitted signal in the time domain, e.g. echo cancellers
• CPC Class Codes: H04B 3/234 using double talk detection
• CPC Class Codes: H04J 3/0632 Synchronisation of packets and cells, e.g. transmission of voice via a packet network, circuit emulation service [CES] queuing arrangements in packet switching elements H04L49/90; synchronising systems for the synchronous transmission of a pulse code modulated video signal with one or more other pulse code modulated signals H04N7/56
• CPC Class Codes: H04J 3/0638 Clock or time synchronisation among nodes; Internode synchronisation synchronization for ring networks H04L12/422; data switching networks with synchronous transmission H04L12/43
• CPC Class Codes: H04L 12/28 characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks] wireless communication networks H04W ; arrangements for dividing the transmission path H04W40/00
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: H04L 12/2834 Switching of information between an external network and a home network access arrangements H04L12/2856
• CPC Class Codes: H04L 12/5692 Selection among different networks
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• CPC Class Codes: H04L 65/1069 Session establishment or de-establishment
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04M 7/006 Networks other than PSTN/ISDN providing telephone service, e.g. Voice over Internet Protocol (VoIP) , including next generation networks with a packet-switched transport layer H04L65/00 takes precedence; aspects not specific to the type of network H04M3/00; special services in those networks H04M3/42
• CPC Class Codes: H04M 7/0087 Network planning or provisioning
• CPC Class Codes: H04M 7/125 Details of gateway equipment
• CPC Class Codes: H04M 9/08 Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic
• CPC Class Codes: H04N 21/2383 Channel coding or modulation of digital bit-stream, e.g. QPSK modulation arrangements for detecting or preventing errors in the information received by adapting the channel coding H04L1/0009; analogue front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/4382 Demodulation or channel decoding, e.g. QPSK demodulation analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 7/10 Adaptations for transmission by electrical cable H04N7/12 takes precedence

Abstract

A network gateway is configured to facilitate on line and off line bi-directional communication between a number of near end data and telephony devices with far end data termination devices via a hybrid fiber coaxial network and a cable modem termination system. The described network gateway combines a QAM receiver, a transmitter, a DOCSIS MAC, a CPU, a voice and audio processor, a voice synchronizer, an Ethernet MAC, and a USB controller to provide high performance and robust operation.

Claims

1. A cable modem, comprising:

a network port to interface with a cable head end;

a telephony port to interface with a telephony device;

a data port to interface with a data terminal; and

a processor coupled to each of the ports.

2. The cable modem of claim 1 further comprising a transceiver coupled between the processor and the network port.

3. The cable modem of claim 2 wherein the transceiver comprises a media access controller (MAC) coupled to the processor, and a modulator and a demodulator both disposed between the MAC and the network port.

4. The cable modem of claim 1 wherein the processor determines whether voice signals from the network port are destined for the data port or the telephony port and couples the voice signals to one of the data port and telephony port based on such determination.

5. The cable modem of claim 1 further comprising a voice circuit coupled between the telephony port and the processor.

6. A gateway, comprising:

a network port to interface with a cable head end;

a telephony port to interface to a telephony device;

a data port to interface to a data terminal;

a processor coupled to each of the ports; and

a transceiver disposed between the processor and the network port, the transceiver being capable of transmitting and receiving packets of voice signals, packets of data signals, and a television signal.

7. The gateway of claim 6 wherein the transceiver comprises a media access controller (MAC) coupled to the processor, and a modulator and a demodulator both disposed between the MAC and the network port.

8. The gateway of claim 6 wherein the processor determines whether the voice signals from the network port are destined for the data port or the telephony port and couples the voice signals to one of the data port and telephony port based on such determination.

9. The gateway of claim 6 further comprising a voice circuit coupled between the telephony port and the processor.

10. A method of processing signals, comprising:

exchanging voice signals between a cable head end and a telephony device;

exchanging data signals between the cable head end and a data terminal; and

receiving a television signal from the cable head end.

11. The method of claim 10 further comprising demodulating the signals flowing from the head end to the telephony device and the data terminal, and modulating the signals flowing from the telephony device and the data terminal to the cable head end.

12. The method of claim 10 wherein the data signal exchange comprises receiving and transmitting the data signals to the data terminal over a local area network.

13. The method of claim 10 wherein the voice signal exchange comprises receiving and transmitting the voice signals to the telephony device over a telephone line.

14. The method of claim 13 wherein the voice signal exchange further comprises exchanging second voice signals between the cable head end and a second telephony, the second voice signal exchange comprising receiving and transmitting the second voice signals to the second telephony device over the local area network.

15. The method of claim 10 wherein the voice exchange comprises canceling a cable head end echo on the voice signal flowing from the telephony device to the cable head end.

16. The method of claim 15 wherein the echo cancellation comprises adaptively filtering a cable head end signal from the cable head end based on adaptation coefficients, detecting whether speech is present on the voice signal, holding the adaptation coefficients constant when speech is present, and canceling the cable head end echo from the telephony signal after the adaptation coefficients are held constant.

17. The method of claim 16 wherein the echo cancellation further comprises subtracting the adaptively filtered cable head end signal from the voice signal.

18. The method of claim 16 wherein the echo cancellation further comprises delaying the cancellation of the echo from the voice signal for a time after the detection of speech.

19. The method of claim 16 wherein the detection of speech comprises estimating an absolute value of a cable head end signal parameter, estimating a maximum parameter of the voice signal, comparing the absolute value of the cable head end signal parameter to the estimated maximum parameter of the voice signal, and detecting speech on the voice signal as a function of the comparison.

20. The method of claim 16 wherein the echo cancellation further comprising pre-conditioning the voice signal prior to the detection of speech thereon.

21. The method of claim 20 wherein the pre-conditioning the voice signal comprises adaptively filtering the cable head end signal and subtracting the adaptively filtered cable head end signal from the voice signal.

22. The method of claim 10 wherein the voice exchange synchronizes the voice signal between the cable head end and the telephony device.

23. The method of claim 22 wherein the voice synchronization comprises generating an error signal as a function of a difference between a cable head end clock and a voice exchange clock, and fractionally resampling the voice signal as a function of the error signal.

24. The method of claim 23 wherein the generation of the error signal comprises driving a first counter with the cable head end clock, and driving a second counter with the voice exchange clock, wherein the error signal is generated by dividing an output of the first counter by an output of the second counter.

25. The method of claim 24 wherein the voice synchronization further comprises fractionally up-sampling the voice signal by the error signal when the output of the first counter exceeds the output of the second counter.

26. The method of claim 24 wherein the voice synchronization further comprises fractionally down-sampling the voice signal by the error signal when the output of the first counter is less than the output of the second counter.

27. The method of claim 24 wherein the voice synchronization further comprises filtering the output of said first and second clocks, wherein the error signal is generated by dividing the filtered output of the first counter by the filtered output of the second counter.

28. The method of claim 10 further comprising discriminating between said voice and data signals and decimating a received signal in accordance with said discrimination.

29. The method of claim 28 wherein voice signals received from said voice terminal are decimated with a minimum phase filter.

30. The method of claim 28 wherein data signals received from said data terminal are decimated with a linear phase filter.

31. A cable modem, comprising:

a first network port to interface with a cable head end;

a second network port to interface with a local area network; and

a processor coupled to each of the ports.

32. The cable modem of claim 31 wherein the local area network comprises a packet based network.

33. The cable modem of claim 32 wherein the packet based network comprises data packets superimposed on a voiceband signal.

34. The cable modem of claim 33 wherein the data packets are modulated at a frequency above frequency of said voiceband signal.

35. The cable modem of claim 32 wherein the packet based network comprises a twisted pair telephone line.

36. The cable modem of claim 32 wherein the packet based network comprises a protocol for home communications over a twisted pair telephone line.

37. The cable modem of claim 32 wherein the packet based network comprises an Ethernet line.

38. The cable modem of claim 31 further comprising a transceiver coupled between the processor and the first network port.

39. The cable modem of claim 38 wherein the transceiver comprises a media access controller (MAC) coupled to the processor, and a modulator and a demodulator both disposed between the MAC and the first network port.

40. The cable modem of claim 31 further comprising a voice circuit coupled between the second network port and the processor.

41. The cable modem of claim 31 further comprising a voice synchronizer that generates an error signal as a function of a difference between a cable head end clock and a local clock for synchronizing voice signals communicated between said cable head end and said cable modem.

42. The cable modem of claim 41 further comprising a time stamp register wherein said cable modem periodically writes value of error signal into said time stamp register and transports said value of said error signal over said second network port to synchronize telephony devices coupled to said local area network.

43. A gateway, comprising:

a first network port to interface with a cable head end;

a second network port to interface to a local area network;

a processor coupled to each of the ports; and

a transceiver disposed between the processor and the first network port, the transceiver being capable of transmitting and receiving packets of voice signals, packets of data signals, and a television signal.

44. The gateway of claim 43 wherein the local area network comprises a packet based network.

45. The gateway of claim 44 wherein the packet based network comprises a twisted pair telephone line.

46. The gateway of claim 44 wherein the packet based network comprises a protocol for home communications over a twisted pair telephone line.

47. The cable modem of claim 44 wherein the packet based network comprises am Ethernet line.

48. The gateway of claim 43 wherein the transceiver comprises a media access controller (MAC) coupled to the processor, and a modulator and a demodulator both disposed between the MAC and the first network port.

49. The gateway of claim 43 further comprising a voice circuit coupled between the second network port and the processor.

50. A method of processing signals, comprising:

exchanging voice signals between a cable head end and a local area network;

exchanging data signals between the cable head end and the local area network; and

receiving a television signal from the cable head end.

51. The method of claim 50 wherein the local area network comprises a packet based network.

52. The method of claim 51 wherein the packet based network comprises a twisted pair telephone line.

53. The method of claim 51 wherein the packet based network comprises a protocol for home communications over a twisted pair telephone line.

54. The method of claim 51 wherein the packet based network comprises an Ethernet line.

55. The method of claim 51 wherein the packet based network comprises data packets superimposed on a voiceband signal.

56. The method of claim 51 wherein the data packets are modulated at a frequency above frequency of said voiceband signal.

57. The method of claim 50 further comprising demodulating the signals flowing from the head end to the local area network, and modulating the signals flowing from the local area network to the cable head end.

58. The method of claim 50 wherein the voice exchange comprises canceling a cable head end echo on the voice signal flowing from the local area network to the cable head end.

59. The method of claim 58 wherein the echo cancellation comprises adaptively filtering a cable head end signal from the cable head end based on adaptation coefficients, detecting whether speech is present on the voice signal, holding the adaptation coefficients constant when speech is present, and canceling the cable head end echo from the voice signal after the adaptation coefficients are held constant.

60. The method of claim 59 wherein the echo cancellation further comprises subtracting the adaptively filtered cable head end signal from the voice signal.

61. The method of claim 59 wherein the echo cancellation further comprises delaying the cancellation of the echo from the voice signal for a time after the detection of speech.

62. The method of claim 59 wherein the detection of voice comprises estimating an absolute value of a cable head end signal parameter, estimating a maximum parameter of the voice signal, comparing the absolute value of the cable head end signal parameter to the estimated maximum parameter of the voice signal, and detecting speech on the voice signal as a function of the comparison.

63. The method of claim 59 wherein the echo cancellation further comprising pre-conditioning the voice signal prior to the detection of speech thereon.

64. The method of claim 61 wherein the pre-conditioning the voice signal comprises adaptively filtering the cable head end signal and subtracting the adaptively filtered cable head end signal from the voice signal.

65. The method of claim 50 wherein the voice exchange synchronizes the voice signal between the cable head end and the local area network.

66. The method of claim 65 wherein the voice synchronization comprises generating an error signal as a function of a difference between a cable head end clock and a voice exchange clock, and fractionally resampling the voice signal as a function of the error signal.

67. The method of claim 66 wherein the generation of the error signal comprises driving a first counter with the cable head end clock, driving a second counter with the voice exchange clock, wherein the error signal is generated by dividing an output of the first counter by an output of the second counter.

68. The method of claim 67 wherein the voice synchronization further comprises fractionally up-sampling the voice signal by the error signal when the output of the first counter exceeds the output of the second counter.

69. The method of claim 67 wherein the voice synchronization further comprises fractionally down-sampling the voice signal by the error signal when the output of the first counter is less than the output of the second counter.

70. The method of claim 67 wherein the voice synchronization further comprises filtering the output of said first and second clocks, wherein the error signal is generated by dividing the filtered output of the first counter by the filtered output of the second counter.

71. The method of claim 66 further comprising periodically communicating value of said error signal over said local area network to synchronize telephony devices coupled to said local area network.

72. The method of claim 50 further comprising remotely controlling subscriber access to said television signal.

73. The method of claim 50 further comprising communicating a timestamp report to devices coupled to said local area network for generating value in accordance with offset between cable modem clock and local area network clock.

74. The method of claim 73 further comprising communicating grant receive value to said devices coupled to said local area network, wherein said devices communicate packets to said cable modem in accordance with said grant receive and said offset value so that the packets arrive at the cable modem just in time for the next upstream grant.

75. The method of claim 74 further comprising generating a packet assembly start time in accordance with said offset value, grant receive value, packet assembly overhead, queuing latency and transmission time to insure the packets arrive at the cable modem just in time for the next upstream grant.

76. The method of claim 50 further comprising discriminating between said voice and data signals and decimating a signal received from said local area network in accordance with said discrimination.

77. The method of claim 76 wherein voice signals received from said local area network are decimated with a minimum phase filter.

78. The method of claim 76 wherein data signals received from said local area network are decimated with a linear phase filter.

80. The gateway of claim 79 further comprising means for demodulating the signals flowing from the head end to the telephony device and the data terminal, and means for modulating the signals flowing from the telephony device and the data terminal to the cable head end.

81. The gateway of claim 79 wherein the data means comprises means for receiving and transmitting the data signals to the data terminal over a local area network.

82. The gateway of claim 79 wherein the voice means comprises means for receiving and transmitting the voice signals to the telephony device over a telephone line.

83. The gateway of claim 82 wherein the voice means further comprises second voice means for exchanging second voice signals between the cable head end and a second telephony, the second voice means comprising means receiving and transmitting the second voice signals to the second telephony device over the local area network.

84. The gateway of claim 79 wherein the voice means comprises echo cancellation means for canceling a cable head end echo on the voice signal flowing from the telephony device to the cable head end.

85. The gateway of claim 84 wherein the echo cancellation means comprises means for adaptively filtering a cable head end signal from the cable head end based on adaptation coefficients, means for detecting whether speech is present on the voice signal, means for holding the adaptation coefficients constant when speech is present, and means for canceling the cable head end echo from the telephony signal after the adaptation coefficients are held constant.

86. The gateway of claim 85 wherein the echo cancellation means further comprises means for subtracting the adaptively filtered cable head end signal from the voice signal.

87. The gateway of claim 85 wherein the echo cancellation means further comprises means for delaying the cancellation of the echo from the voice signal for a time after the detection of speech.

88. The gateway of claim 85 wherein the means for detecting whether speech is present on the voice signal comprises means for estimating an absolute value of a cable head end signal parameter, means for estimating a maximum parameter of the voice signal, means for comparing the absolute value of the cable head end signal parameter to the estimated maximum parameter of the voice signal, and means for detecting speech on the voice signal as a function of the comparison.

89. The gateway of claim 85 wherein the echo cancellation means further comprises pre-conditioning means for pre-conditioning the voice signal prior to the detection of speech thereon.

90. The gateway of claim 89 wherein the pre-conditioning means comprises means for adaptively filtering the cable head end signal and means for subtracting the adaptively filtered cable head end signal from the voice signal.

91. The gateway of claim 79 wherein the voice exchange means comprises synchronization means for synchronizing the voice signal between the cable head end and the telephony device.

92. The gateway of claim 91 wherein the synchronization means comprises generation means for generating an error signal as a function of a difference between a cable head end clock and a voice exchange clock, and means for fractionally resampling the voice signal as a function of the error signal.

93. The gateway of claim 92 wherein the generation means comprises means for driving a first counter with the cable head end clock, means for driving a second counter with the voice exchange clock, and means for dividing an output of the first counter by an output of the second counter to generate the error signal.

94. The gateway of claim 93 wherein the synchronization means further comprises means for fractionally up-sampling the voice signal by the error signal when the output of the first counter exceeds the output of the second counter.

95. The gateway of claim 93 wherein the synchronization means further comprises fractionally down-sampling the voice signal by the error signal when the output of the first counter is less than the output of the second counter.

96. The gateway of claim 93 wherein the synchronization means further comprises means for filtering the output of said first and second clocks, and means for dividing the filtered output of the first counter by the filtered output of the second counter to generate the error signal.

79. A gateway, comprising:

voice means for exchanging voice signals between a cable head end and a telephony device;

data means for exchanging data signals between the cable head end and a data terminal; and

means for receiving a television signal from the cable head end.

97. A gateway, comprising:

voice means for exchanging voice signals between a cable head end and a local area network;

data means for exchanging data signals between the cable head end and the local area network; and

means for receiving a television signal from the cable head end.

98. The gateway of claim 97 wherein the local area network comprises a packet based network.

99. The gateway of claim 98 wherein the packet based network comprises a twisted pair telephone line.

100. The gateway of claim 98 wherein the packet based network comprises a protocol for home communications over a twisted pair telephone line.

101. The gateway of claim 98 wherein the packet based network comprises am Ethernet line.

102. The gateway of claim 97 further comprising means for demodulating the signals flowing from the head end to the telephony device and the data terminal, and means for modulating the signals flowing from the telephony device and the data terminal to the cable head end.

103. The gateway of claim 97 wherein the data means comprises means for receiving and transmitting the data signals to the data terminal over a local area network.

104. The gateway of claim 97 wherein the voice means comprises means for receiving and transmitting the voice signals to the telephony device over a telephone line.

105. The gateway of claim 104 wherein the voice means further comprises second voice means for exchanging second voice signals between the cable head end and a second telephony, the second voice means comprising means receiving and transmitting the second voice signals to the second telephony device over the local area network.

106. The gateway of claim 97 wherein the voice means comprises echo cancellation means for canceling a cable head end echo on the voice signal flowing from the telephony device to the cable head end.

107. The gateway of claim 106 wherein the echo cancellation means comprises means for adaptively filtering a cable head end signal from the cable head end based on adaptation coefficients, means for detecting whether speech is present on the voice signal, means for holding the adaptation coefficients constant when speech is present, and means for canceling the cable head end echo from the telephony signal after the adaptation coefficients are held constant.

108. The gateway of claim 107 wherein the echo cancellation means further comprises means for subtracting the adaptively filtered cable head end signal from the voice signal.

109. The gateway of claim 107 wherein the echo cancellation means further comprises means for delaying the cancellation of the echo from the voice signal for a time after the detection of speech.

110. The gateway of claim 107 wherein the means for detecting whether speech is present on the voice signal comprises means for estimating an absolute value of a cable head end signal parameter, means for estimating a maximum parameter of the voice signal, means for comparing the absolute value of the cable head end signal parameter to the estimated maximum parameter of the voice signal, and means for detecting speech on the voice signal as a function of the comparison.

111. The gateway of claim 107 wherein the echo cancellation means further comprises pre-conditioning means for pre-conditioning the voice signal prior to the detection of speech thereon.

112. The gateway of claim 111 wherein the pre-conditioning means comprises means for adaptively filtering the cable head end signal and means for subtracting the adaptively filtered cable head end signal from the voice signal.

113. The gateway of claim 97 wherein the voice exchange means comprises synchronization means for synchronizing the voice signal between the cable head end and the telephony device.

114. The gateway of claim 113 wherein the synchronization means comprises generation means for generating an error signal as a function of a difference between a cable head end clock and a voice exchange clock, and means for fractionally resampling the voice signal as a function of the error signal.

115. The gateway of claim 114 wherein the generation means comprises means for driving a first counter with the cable head end clock, means for driving a second counter with the voice exchange clock, and means for dividing an output of the first counter by an output of the second counter to generate the error signal.

116. The gateway of claim 115 wherein the synchronization means further comprises means for fractionally up-sampling the voice signal by the error signal when the output of the first counter exceeds the output of the second counter.

117. The gateway of claim 115 wherein the synchronization means further comprises fractionally down-sampling the voice signal by the error signal when the output of the first counter is less than the output of the second counter.

118. The gateway of claim 115 wherein the synchronization means further comprises means for filtering the output of said first and second clocks, and means for dividing the filtered output of the first counter by the filtered output of the second counter to generate the error signal.