Information communication system

• US 6,246,716 B1
• Filed: 01/31/1997
• Issued: 06/12/2001
• Est. Priority Date: 01/31/1997
• Status: Expired due to Term

• Current Assignee: ADTRAN Incorporated (ADTRAN Holdings, Inc.)
• Original Assignee: ADTRAN Incorporated (ADTRAN Holdings, Inc.)
• Inventors: Schneider, Kevin Wayne
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): GHAYOUR, MOHAMMAD H
• Application Number:
  US08/792,632
• Time in Patent Office: 1,593 Days
• Field of Search: 375/220, 375/222, 375/286, 375/241, 375/353, 370/201, 370/281
• US Class Current: 375/220
• CPC Class Codes: H04B 3/21 using a set of bandfilters
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04M 11/062 using different frequency bands for speech and other data

Abstract

The present invention is a communication system for communicatinginformation over greater distances than otherwise possible on bidirectional media subject tointerference, by reducing the interference while assuring spectral compatibility with other communication services. The system of the present invention provides symmetric data service to end users by using asymmetric signaling. In one embodiment, the present invention utilizes partially overlapped, non-symmetric baud rates and spectrally shaped transceiver filters to achieve both spectral compatibility and extended range.

Claims

1. A method for simultaneously transmitting data at a symmetrical rate in two directions on a bidirectional medium subject to interference, the method comprising the steps of:

(1) transmitting a first signal in one direction on said medium, said data modulating a first plurality of carriers thereby generating said first signal;

(2) transmitting a second signal in the other direction on said medium said data modulating a second plurality of carriers thereby generating said second signal; and

(3) spectrally shaping at least one passband of said generated signals prior to transmission such that the plurality of passbands of said signals are partially overlapped in such manner that performance margins due to interference caused by signals of the same kind being transmitted on said medium are greater than performance margins in a first design specification and further that interference caused by said first and second signals and said signals of the same kind does not reduce performance margins in different services being transmitted on said medium below performance margins in a second design specification.

4. The method according to claim 1, 2, or 3 further comprising the step of echo canceling said signals.

12. The method according to claim 1, 2, 5, 9, or 10 wherein said spectral shaping comprises transmitting said signals with unequal transmit power in said directions.

16. The method of claim 1, 2, 3, 9 or 10, further comprising the step of swapping a second transmit power spectral density characterizing transmission of said data in said second direction on said medium with a first transmit power spectral density characterizing transmission of said data in said first direction on said medium.

20. The method of claim 1, 2, 3, 9, or 10 wherein said performance margins in said first design specification are determined based on the level of interference caused by said different services being transmitted on said medium.

22. The method of claim 16 wherein said swapping step is performed automatically upon the sensing of an interference level that exceeds a predetermined preselected level.

2. A method for simultaneously transmitting data at a symmetrical data transmission rate in two directions on a bidirectional medium subject to interference, the method comprising the steps of:

(1) transmitting a first signal in one direction on said medium, said data modulating a carrier thereby generating said first signal;

(2) transmitting a second signal in the other direction on said medium said data modulating a carrier thereby generating said second signal; and

,

(3) spectrally shaping said signals prior to transmission such that the passbands of said signals are partially overlapped in such manner that performance margins due to interference caused by signals of the same kind being transmitted on said medium are greater than performance margins in a first design specification and further that interference caused by said first and second signals and said signals of the same kind does not reduce performance margins in different services being transmitted on said medium below performance margins in a second design specification.

3. A method for simultaneously transmitting data at a symmetrical data transmission rate in two directions on a bidirectional medium subject to interference, the method comprising the steps of:

(1) transmitting a first signal in one direction on said medium wherein said first signal is generated by modulating a first carrier at a first baud rate

(2) transmitting a second signal in the other direction on said medium wherein said second signal is generated by modulating a second carrier at a second baud rate; and

(3) spectrally shaping said signals prior to transmission such that the passbands of said signals are partially overlapped in such manner that performance margins due to interference caused by signals of the same kind being transmitted on said medium are greater than performance margins in a first design specification and further that interference caused by said first and second signals and said signals of the same kind does not reduce performance margins in different services being transmitted on said medium below performance margins in a second design specification.

5. The method according to claim 3, wherein said first baud rate differs in magnitude from said second baud rate.

17. The method of claim 3, wherein said first baud rate is equal to said second baud rate.

6. Apparatus for simultaneously transmitting data at a symmetrical transmission rate in two directions on a bidirectional medium subject to interference, said apparatus comprising:

(1) a first transceiver, including an echo canceler, transmitting a first signal comprising a carrier, modulated by said data, in one direction on said medium; and

(2) a second transceiver, including an echo canceler, transmitting a second signal comprising a carrier, modulated by said data, in the other direction on said medium;

said transceivers being so constructed and arranged that said signals are spectrally shaped and echo canceled, such that said signals are transmitted in partially overlapped passbands, the passbands being overlapped in such manner that performance margins due to interference caused by signals of the same kind being transmitted on said medium are greater than performance margins in a first design specification and further that interference caused by said first and second signals and said signals of the same kind does not reduce performance margins in different services being transmitted on said medium below performance margins in a second design specification.

8. The apparatus according to claim 6, wherein each of said transceivers further comprises a channel coder, a pre-equalizer, a line coder, a receiver front end, an adaptive feed forward equalizer, and a decision device.

7. Apparatus for simultaneously communicating data in two directions at a symmetric rate on a bidirectional medium subject to interference, said apparatus comprising:

(1) a first transceiver, including an echo canceler, transmitting a first signal in one direction on said medium wherein the first signal is generated by a first data stream at said symmetric rate modulating a first plurality of carriers; and

(2) a second transceiver, including an echo canceler, transmitting a second signal in the other direction on said medium wherein the second signal is generated by a second data stream at said symmetric rate modulating a second plurality of carriers;

said transceivers being so constructed and arranged that said signals are spectrally shaped prior to transmission such that the plurality of passbands of said signals are partially overlapped in such manner that performance margins due to interference caused by signals of the same kind being transmitted on said medium are greater than performance margins in a first design specification and further such that interference caused by said first and second signals and said signals of the same kind does not reduce performance margins in different services being transmitted on said medium below performance margins in a second design specification.

23. The apparatus according to claim 7, wherein said signals are discrete multi-tone modulated signals.

9. A method for simultaneously communicating data in two directions at a symmetric rate over a twisted copper pair in a cable of twisted copper pairs subject to ingress and egress crosstalk coupling into and from other twisted copper pairs in said cable, the method comprising the steps of:

transmitting a first signal in one direction on said twisted copper pair wherein the first signal is generated by a first data stream at said symmetric rate modulating a first plurality of carriers;

transmitting a second signal in the other direction on said twisted copper pair wherein the second signal is generated by a second data stream at said symmetric rate modulating a second plurality of carriers; and

spectrally shaping said signals prior to transmission such that the passbands of said signals are partially overlapped in such manner that performance margins due to interference caused by signals of the same kind being transmitted on said medium are greater than performance margins in a first design specification and further that interference caused by said first and second signals and said signals of the same kind does not reduce performance margins in different services being transmitted on said medium below performance margins in a second design specification.

10. A method for simultaneously communicating data in two directions at a symmetric rate over a twisted copper pair in a cable subject to ingress and egress crosstalk coupling into and from other twisted copper pairs in the cable, the method comprising the steps of:

transmitting a first signal in one direction on said twisted copper pair wherein the first signal is generated by a first data stream at said symmetric rate modulating a first carrier;

transmitting a second signal in the other direction on said twisted copper pair wherein the second signal is generated by a second data stream at said symmetric rate modulating a second carrier; and

spectrally shaping said signals prior to transmission such that the passbands of said signals are partially overlapped in such manner that performance margins due to interference caused by signals of the same kind being transmitted on said medium are greater than performance margins in a first design specification and further that interference caused by said first and second signals and said signals of the same kind does not reduce performance margins in different services being transmitted on said medium below performance margins in a second design specification.

11. Apparatus using pulse amplitude modulation and echo canceling for simultaneously transmitting data at a symmetrical transmission rate in two directions on a bidirectional medium subject to interference, said apparatus comprising:

(1) a first transceiver, including an echo canceler, transmitting data on said medium in one direction; and

(2) a second transceiver, including an echo canceler, transmitting data on said medium in the other direction;

said transceivers being so constructed and arranged that transmissions on said medium are spectrally shaped and echo canceled, such that said signals are transmitted in partially overlapped passbands, the passbands being overlapped in such manner that performance margins due to interference caused by signals of the same kind being transmitted on said medium are greater than performance margins in a first design specification and further that interference caused by said first and second signals of the same kind does not reduce performance margins in different services being transmitted on said medium below performance margins in a second design specification.

15. The apparatus according to claim 6, 11, 13, 14 or 7 wherein a second transmit power spectral density characterizing said second transceiver is swapped with a first transmit power spectral density characterizing said first transceiver.

18. The apparatus according to claim 6, 11, 13, 14, or 7 wherein said spectrally shaped signals include at least one spectrally shaped stopband, one spectrally shaped passband, and one spectrally shaped transition band.

19. The apparatus according to claim 6, 11, 13, 14, or 7 wherein said spectrally shaped signals are transmitted in said directions with unequal transmit power.

21. The apparatus of claim 6, 11, 13, 14, or 7 wherein said performance margins in said first design specification are determined based on the level of interference caused by said different services being transmitted on said medium.

13. Apparatus for simultaneously communicating data in two directions at a symmetric rate over a twisted copper pair in a cable subject to ingress and egress crosstalk coupling between other twisted copper pairs in said cable, said apparatus comprising:

(1) a first transceiver, including an echo canceler, transmitting a first signal in one direction on said twisted copper pair wherein the first signal is generated by a first data stream at said symmetric rate modulating a first carrier; and

(2) a second transceiver, including an echo canceler, transmitting a second signal in the other direction on said twisted copper pair wherein the second signal is generated by a second data stream at said symmetric rate modulating a second carrier;

said transceivers being so constructed and arranged that said signals are echo canceled and spectrally shaped, such that said signals are transmitted in partially overlapped passbands, the passbands being overlapped in such manner that performance margins due to interference caused by signals of the same kind being transmitted on said cable are greater than performance margins in a first design specification and further that interference caused by said first and second signals and said signals of the same kind does not reduce performance margins in different services being transmitted on said cable below performance margins in a second design specification.

14. Apparatus for simultaneously communicating data in two directions at a symmetric rate over a twisted copper pair in a cable of twisted copper pairs subject to ingress and egress crosstalk coupling into and from other twisted copper pairs in said cable, said apparatus comprising:

(1) a first transceiver, including an echo canceler, transmitting a first signal in one direction on said twisted copper pair wherein the first signal is generated by a first data stream at said symmetric rate modulating a first plurality of carriers; and

(2) a second transceiver, including an echo canceler, transmitting a second signal in the other direction on said twisted copper pair wherein the second signal is generated by a second data stream at said symmetric rate modulating a second plurality of carriers;

said transceivers being so constructed and arranged that said signals are spectrally shaped prior to transmission such that the plurality of passbands of said signals are partially overlapped in such manner that performance margins due to self-crosstalk are greater than performance margins in a first design specification and further such that egress crosstalk from said twisted copper pair does not reduce performance margins in different services deployed in said other twisted copper pairs below performance margins in a second design specification.