Method and apparatus for wideband transmission of digital signals between, for example, a telephone central office and customer premises

• US 4,924,492 A
• Filed: 03/22/1988
• Issued: 05/08/1990
• Est. Priority Date: 03/22/1988
• Status: Expired due to Term

• Current Assignee: American Telephone & Telegraph Company (AT&T, Inc.), AT&T Information Systems Inc. (AT&T, Inc.)
• Original Assignee: American Telephone & Telegraph Company (AT&T, Inc.), AT&T Information Systems Inc. (AT&T, Inc.)
• Inventors: Gitlin, Richard D., Werner, Jean-Jacques, Rao, Sailesh K., Zervos, Nicholas
• Primary Examiner(s): Ng, Jin F.
• Assistant Examiner(s): Chan, Wing F.
• Application Number:
  US07/171,636
• Time in Patent Office: 777 Days
• Field of Search: 379/93, 379/98, 379/97, 379/94, 370/43, 370/119, 370/110.1, 370/32.1, 370/24, 370/29, 370/30, 370/69.1, 370/76, 375/13, 375/39, 375/8, 371/43
• US Class Current: 379/93.08
• CPC Class Codes: H04L 25/4921 using quadrature encoding, e.g. carrierless amplitude-phase coding
• CPC Class Codes: H04L 27/3438 using an underlying generalised cross constellation

Abstract

In a telephone local loop transmission arrangement, data is communicated from the customer premises to the central office utilizing a multi-dimensional, passband signal illustratively at 480 kb/s and 1.544 Mb/s.

Claims

1. A data communication method comprising the steps of

generating an outbound passband signal representing a stream of outbound data bits,

applying said outbound passband signal to a two-wire telephone local loop,

receiving over said telephone local loop an inbound passband signal representing a stream of inbound data bits, said inbound passband signal including echoes of said outbound passband signal,

generating a replica of said echoes,

substracting said replica from said inbound passband signal to generate an echo compensated signal, and

recovering said inbound data bits from said echo-compensated signal,

at least one of said inbound or outbound bit streams being at a rate of at least 160 kb/s.

2. The method of claim 1 wherein at least one of said bit streams is at a rate of at least 480 kb/s.

3. The method of claim 1 wherein at least one of said bit streams is at a rate of at least 1.544 Mb/s.

4. The method of claim 1 wherein said outbound passband signal is a carrierless amplitude-and-phase modulated signal.

5. The method of claim 1 wherein said outbound passband signal is a signal representing a stream of channel symbols selected from a predetermined signal constellation, said channel symbols being selected as a function of a trellis coded version of said stream of outbound data bits.

6. The method of claim 1 wherein said inbound passband signal represents said inbound data in a stream of channel symbols selected from a predetermined signal constellation, said channel symbols being selected as a function of a trellis coded version of said stream of inbound data bits, and wherein said recovering step includes the steps of

adaptively equalizing said inbound passband signal,

recovering said stream of channel symbols by Viterbi decoding the resulting equalized signal, and

recovering said inbound data bits from the recovered channel symbols.

7. A data communication method comprising the steps of

generating an outbound passband signal representing a stream of channel symbols selected from a predetermined signal constellation, said channel symbols being selected as a function of a stream of outbound data bits,

applying said outbound passband signal to a two-wire telephone local loop,

receiving an inbound passband signal representing a stream of inbound channel symbols selected from said predetermined signal constellation, said channel symbols having been selected as a function of a stream of inbound data bits, said inbound passband signal including echoes of said outbound passband signal,

generating an adaptively equalized version of said inbound passband signal from which a replica of said echoes has been subtracted,

recovering said stream of inbound channel symbols from the resulting equalized signal, and

recovering said inbound data bits from the recovered inbound channel symbols,

at least one of said inbound or outbound streams of data bits being at a rate of at least 160 kb/s.

8. The method of claim 7 wherein each of said outbound and inbound passband signals is a carrierless amplitude-and-phase modulated signal.

9. The method of claim 7 wherein at least one of said bit streams is at a rate of at least 480 kb/s.

10. The method of claim 7 wherein at least one of said bit streams is at a rate of at least 1.544 Mb/s.

11. A data communication method comprising the steps of

generating an outbound passband signal representing a stream of channel symbols selected from a predetermined signal constellation, said channel symbols being selected as a function of a trellis coded version of a stream of outbound data bits,

applying said outbound passband signal to a two-wire telephone local loop,

receiving an inbound passband signal representing a stream of inbound channel symbols selected from said predetermined signal constellation, said channel symbols having been selected as a function of a trellis coded version of a stream of inbound data bits, said inbound passband signal including echoes of said outbound passband signal,

generating an adaptively equalized version of said inbound passband signal from which a replica of said echoes has been subtracted,

recovering said stream of inbound channel symbols by Viterbi decoding the resulting equalized signal, and

recovering said inbound data bits from the recovered inbound channel symbols,

at least one of said inbound or outbound streams of data bits being at a rate of at least 160 kb/s.

12. The method of claim 11 wherein each of said outbound and inbound passband signals is a carrierless amplitude-and-phase modulated signal.

13. The method of claim 11 wherein at least one of said bit streams is at a rate of at least 480 kb/s.

14. The method of claim 11 wherein at least one of said bit streams is at a rate of at least 1.544 Mb/s.

15. A network termination comprising

transmitter means operative in response to receipt of a stream of outbound data bits for generating an outbound passband signal representing said outbound data bits,

means for applying said outbound passband signal to a two-wire telephone local loop, and

receiver means operative in response to an inbound passband signal which represents a stream of inbound data bits and which includes echoes of said outbound passband signal for recovering said inbound data bits from said inbound passband signal, said inbound passband signal having been received over a signal path which includes said two-wire telephone local loop,

said receiver means including echo canceller means for generating a replica of said echoes and means for subtracting said replica from said inbound passband signal prior to the recovery of said inbound data bits therefrom,

at least one of said inbound or outbound bit streams being at a rate of at least 160 kb/s.

16. The invention of claim 15 wherein at least one of said bit streams is at a rate of at least 480 kb/s.

17. The invention of claim 15 wherein at least one of said bit streams is at a rate of at least 1.544 Mb/s.

18. The invention of claim 15 wherein said transmitter means includes means for generating as said outbound passband signal a carrierless amplitude-and-phase modulated signal.

19. The invention of claim 15 wherein said transmitter means generates as said outbound passband signal a signal representing a stream of channel symbols selected from a predetermined signal constellation, said channel symbols being selected as a function of a trellis coded version of said stream of outbound data bits.

20. The invention of claim 15 wherein said inbound passband signal represents said inbound data in a stream of channel symbols selected from a predetermined signal constellation, said channel symbols being selected as a function of a trellis coded version of said stream of inbound data bits, and wherein said receiver means includes means for adaptively equalizing said inbound passband signal, means for recovering said stream of channel symbols by Viterbi decoding the resulting equalized signal, and means for recovering said inbound data bits from the recovered channel symbols.

21. In combination,

a two-wire telephone local loop,

transmitter means for generating an outbound passband signal representing a stream of channel symbols selected from a predetermined signal constellation, said channel symbols being selected as a function of a stream of outbound data bits,

means for applying said outbound passband signal to said two-wire telephone local loop,

means for receiving an inbound passband signal representing a stream of inbound channel symbols selected from said predetermined signal constellation, said channel symbols having been selected as a function of a stream of inbound data bits, said inbound passband signal including echoes of said outbound passband signal,

means for generating an adaptively equalized version of said inbound passband signal from which a replica of said echoes has been subtracted,

means for recovering said stream of inbound channel symbols from the resulting equalized signal, and

means for recovering said inbound data bits from the recovered inbound channel symbols,

at least one of said inbound or outbound streams of data bits being at a rate of at least 160 kb/s.

22. The invention of claim 21 wherein each of said outbound and inbound passband signals is a carrierless amplitude-and-phase modulated signal.

23. The invention of claim 21 wherein at least one of said bit streams is at a rate of at least 480 kb/s.

24. The invention of claim 21 wherein at least one of said bit streams is at a rate of at least 1.544 Mb/s.

25. A network termination comprising

transmitter means for generating an outbound passband signal representing a stream of channel symbols selected from a predetermined signal constellation, said channel symbols being selected as a function of a trellis coded version of a stream of outbound data bits,

means for applying said outbound passband signal to a two-wire telephone local loop,

means for receiving an inbound passband signal representing a stream of inbound channel symbols selected from said predetermined signal constellation, said channel symbols having been selected as a function of a trellis coded version of a stream of inbound data bits, said inbound passband signal including echoes of said outbound passband signal,

means for generating an adaptively equalized version of said inbound passband signal from which a replica of said echoes has been subtracted,

means for recovering said stream of inbound channel symbols by Viterbi decoding the resulting equalized signal, and

means for recovering said inbound data bits from the recovered inbound channel symbols,

at least one of said inbound or outbound streams of data bits being at a rate of at least 160 kb/s.

26. The invention of claim 25 wherein each of said outbound and inbound passband signals is a carrierless amplitude-and-phase modulated signal.

27. The invention of claim 25 wherein at least one of said bit streams is at a rate of at least 480 kb/s.

28. The invention of claim 25 wherein at least one of said bit streams is at a rate of at least 1.544 Mb/s.