Noncooperative feedback system and method for a compensation system associated with transmitter or codec

• US 6,072,825 A
• Filed: 09/23/1997
• Issued: 06/06/2000
• Est. Priority Date: 08/23/1996
• Status: Expired due to Term

• Current Assignee: Intellectual Properties I KFT
• Original Assignee: Paradyne Corporation (Dasan Networks Incorporated)
• Inventors: Betts, William Lewis, Souders, Keith Alan
• Primary Examiner(s): TSE, YOUNG TOI
• Application Number:
  US08/936,054
• Time in Patent Office: 987 Days
• Field of Search: 375/221, 375/222, 375/219, 375/220, 375/254, 375/285, 375/296, 375/358, 375/377, 370/249, 370/523, 714/748, 714/750
• US Class Current: 375/222
• CPC Class Codes: H04J 3/125 One of the channel pulses or the synchronisation pulse is also used for transmitting monitoring or supervisory signals
• CPC Class Codes: H04L 25/4927 using levels matched to the quantisation levels of the channel
• CPC Class Codes: H04Q 11/0421 Circuit arrangements therefor

Abstract

A noncooperative feedback system is provided for a compensation system associated with, for example, a transmitter or codec, for enabling the compensation system to improve the accuracy of digital signals transmitted to a, digital network. The noncooperative feedback system is particularly suited for providing feedback to a compensation system for correcting distortion resulting from rob bit signaling (RBS), digital loss, or other types of digital signal degradation. The noncooperative feedback system includes a compensation selector in a transmitter (e.g., digital modem, analog modem, codec, etc.) that combines different compensations with frames of digital data by way of an addition mechanism to produce modified digital data frames. The transmitter is configured to transmit the modified digital data frames into the digital network. A receiver (e.g., digital modem, analog modem, etc.) is configured to receive the modified digital data frames from the digital network and to communicate retransmission requests to the transmitter via the digital network when the data is inadequate. The adequacy of the data may be determined via any suitable method, for example, analyzing the signal-to-noise ratio. The compensation selector in the transmitter is configured to receive the retransmission requests and to select and implement the compensation that yields a lowest error based upon the transmission requests.

Claims

1. A modem comprising:

a receive subsystem configured to receive retransmission requests from a remote modem and to transmit a feedback signal based on said retransmission requests; and

a transmit subsystem configured to combine different compensations with segments of digital data to produce modified digital data segments, said compensations for correcting for distortion from rob bit signalling, said transmit subsystem configured to transmit said modified digital data segments into a digital network, said transmit subsystem interfaced with said receive subsystem and configured to select and implement which of said compensations yields a lowest error based upon said feedback signal.

2. The modem of claim 1, wherein said transmit subsystem is configured to add a quantity to a frame of said digital data as each of said compensations.

3. A noncooperative feedback system for improving accuracy of a digital signal transmitted to a digital network, comprising:

means for combining at a transmitter a plurality of compensations to segments of digital data respectively to produce modified digital data segments, said compensations for correcting for distortion from rob bit signalling;

means for communicating said modified digital data segments from said transmitter to a receiver;

means for receiving retransmission requests from said receiver; and

means for determining which of said compensations yields a lowest error based upon said retransmission requests.

4. A noncooperative feedback method for enabling improvement of a digital signal transmitted to a digital network, comprising the steps of:

combining at a transmitter a plurality of compensations to segments of digital data respectively to produce modified digital data segments, said compensations for correcting for rob bit signalling;

communicating said modified digital data segments from said transmitter to a receiver;

receiving retransmission requests from said receiver; and

determining which of said compensations yields a lowest error based upon said retransmission requests.

5. The method of claim 4, further comprising the step of communicating said segments through said digital network wherein said network periodically robs a bit.

6. The method of claim 4, further comprising the steps of:

converting said digital data from linear digital data to mu-law digital data; and

communicating said mu-law digital data through said digital network.

7. The method of claim 4, further comprising the step of modifying every nth frame of said digital data after said determining step, where n is a mathematical multiple of number six.

8. A noncooperative feedback system, comprising:

a receiver configured to receive retransmission requests transmitted from a remote modem and to transmit a feedback signal based on said retransmission requests; and

a transmitter responsive to said feedback signal for selecting a compensation quantity to combine with a frame of digital data in order to compensate said frame for distortion due to rob bit signalling.

9. The system of claim 8, wherein said quantity is 0.5 of a least significant bit.

10. The system of claim 8, wherein said receiver further comprises an error correction mechanism configured to receive said retransmission requests and to determine whether said frame of digital data is subject to said distortion from said rob bit signalling based on said retransmission requests, and wherein said transmitter is further configured to receive said feedback signal and to compensate for distortion from said rob bit signalling based on said feedback signal.

11. The system of claim 10, wherein said feedback signal includes a pattern indicating which of said frames of data are subject to said distortion from said rob bit signalling.

12. A noncooperative feedback method, comprising the steps of:

combining compensation quantities to frames of digital data to compensate for distortion due to rob bit signalling;

receiving a number of retransmission requests; and

selecting said compensation quantities based on said number of retransmission requests.

13. A noncooperative feedback method, comprising the steps of:

receiving an error signal from a remote communications device;

combining a compensation quantity to frames of digital data to reduce distortion associated with rob bit signalling;

generating a quality feedback signal based on said error signal, said quality feedback signal indicating a quality of said frames of digital data; and

selecting said compensation quantity based on said quality feedback signal.

14. The method of claim 13, further comprising the step of:

determining which of said frames of digital data are distorted by rob bit signalling based on said error signal,

wherein said quality feedback signal further indicates which of said frames of digital data are distorted from said rob bit signalling.

15. The method of claim 13, wherein said compensation quantity increases a number of bits of said frames of digital data.

16. A noncooperative feedback system, comprising:

a receiver configured to receive a signal from a remote communications device and to produce a feedback signal based on said signal received from said remote communications device; and

a transmitter responsive to said feedback signal for selecting a compensation quantity to combine with a frame of digital data in order to compensate said frame for distortion due to rob bit signalling.

17. The system of claim 16, wherein said feedback signal indicates a quality of signals received by said remote communications device.

18. The system of claim 16, wherein said feedback signal is responsive to a number of retransmission requests received from said remote communications device.

19. The system of claim 16, wherein said feedback signal is responsive to a quality of signals received by said remote communications device wherein said signals are generated by said transmitter.

20. The system of claim 16, wherein said feedback signal is responsive to a data rate of signal received by said remote communications device, wherein said signals are transmitted by said transmitter.

21. The system of claim 16, wherein said receiver further comprises an error correction mechanism configured to receive error signals generated by said remote communications device, to determine whether said frame of digital data is subject to said distortion from said rob bit signalling, and to generate said feedback signal.

22. A noncooperative feedback method for improving accuracy of digital data transmitted through a digital network, said digital network receiving frames of said digital data, periodically selecting ones of said frames, and forcing a particular bit of selected ones of said frames to a certain logic level, said method comprising the steps of:

receiving signals from a remote modem;

producing a feedback signal based on said signals received from said remote modem, said feedback signal indicating which of said frames of said digital data are subject to distortion from said digital network forcing said particular bit of said selected ones of said frames to said certain logic level; and

compensating said selected ones of said frames for said distortion based on said feedback signal.

23. The method of claim 22, wherein said compensating step further includes the step of combining compensation quantities to said selected ones of said frames.

24. A noncooperative feedback system, comprising:

a receiver for receiving a signal from a remote modem and for producing a feedback signal based on said signal; and

a transmitter responsive to said feedback signal for compensating a frame of digital data for distortion due to rob bit signalling.

25. The system of claim 24, wherein said transmitter compensates for said distortion by combining a compensation quantity to said frame of digital data based on said feedback signal.

26. A modem comprising:

a receive subsystem configured to receive retransmission requests from a remote modem and to transmit a feedback signal based on said retransmission requests; and

a transmit subsystem configured to combine different compensations with segments of digital data to produce modified digital data segments, said transmit subsystem configured to transmit said modified digital data segments into a digital network, said transmit subsystem interfaced with said receive subsystem and configured to select and implement which of said compensations yields a lowest error based upon said feedback signal, said transmit subsystem comprising;

a selector configured to produce mark and space initialization signals based upon said feedback signal;

a mark ring counter configured to receive said mark initialization signal, said mark ring counter configured to generate a mark ring counter signal during each clocked shift of said mark ring counter;

a space ring counter configured to receive said space initialization signal, said space ring counter configured to generate a space ring counter signal during each clocked shift of said space ring counter;

a mark adder configured to mathematically combine a quantity with said digital data based upon said mark ring counter signal; and

a space adder configured to mathematically combine a quantity with said digital data based upon said space ring counter signal.

27. A noncooperative feedback system for improving accuracy of digital data transmitted across a digital network, comprising:

means for receiving retransmission requests;

means for determining which frames of digital data are subject to distortion from rob bit signalling based on said retransmission requests;

means for compensating said frames of digital data determined by said determining means to be subject to said distortion in order to correct for said distortion from said rob bit signalling; and

means for transmitting said frames of digital data.

28. The system of claim 27, wherein said means for compensating includes an adder for combining compensation quantities to said frames of digital data.

29. The system of claim 27, wherein said means for determining includes an error correction mechanism responsive to error signals for determining which frames of digital data have been distorted by said rob bit signalling and for generating a quality feedback signal indicating which frames of digital data are subject to said distortion from said rob bit signalling.

30. The system of claim 29, wherein said error signals are retransmission requests.

31. A noncooperative feedback method for improving accuracy of digital data transmitted through a digital network that distorts said digital data by rob bit signalling (RBS), comprising the steps of:

receiving a signal from a remote communications device;

producing a feedback signal based on said signal received from said remote communications device, said feedback signal indicating which frames of digital data are RBS frames;

compensating said RBS frames, based on said feedback signal, for distortion associated with said RBS; and

transmitting said RBS frames through said digital network.

32. The method of claim 31, wherein said compensating step includes the step of combining a compensation quantity to said RBS frames.