Method and system for crosstalk cancellation

• US 7,626,916 B2
• Filed: 01/19/2006
• Issued: 12/01/2009
• Est. Priority Date: 08/07/2003
• Status: Expired due to Fees

• Current Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Original Assignee: Quellan, Inc. (Renesas Electronics Corporation)
• Inventors: Vrazel, Michael G., Kim, Andrew Joo, Bajekal, Sanjay, Summers, Charles
• Primary Examiner(s): MARCELO, MELVIN C
• Application Number:
  US11/334,864
• Publication Number:
  US 20060159002A1
• Time in Patent Office: 1,412 Days
• Field of Search: 370/201, 370/286
• US Class Current: 370/201
• CPC Class Codes: H04B 3/23 using a replica of transmitted signal in the time domain, e.g. echo cancellers
• CPC Class Codes: H04B 3/238 using initial training sequence
• CPC Class Codes: H04B 3/32 Reducing cross-talk, e.g. by compensating
• CPC Class Codes: H04J 1/12 Arrangements for reducing cross-talk between channels in line transmission systems H04B3/32; in cables or lines H04B3/26 - H04B3/30

Abstract

Signals propagating in one communication channel can generate crosstalk interference in another communication channel. A crosstalk cancellation device can process the signals causing the crosstalk interference and generate a crosstalk cancellation signal that can compensate for the crosstalk when applied to the channel receiving crosstalk interference. The crosstalk cancellation device can include a model of the crosstalk effect that generates a signal emulating the actual crosstalk both in form an in timing. The crosstalk cancellation device can include a controller that monitors crosstalk-compensated communication signals and adjusts the model to enhance crosstalk cancellation performance. The crosstalk cancellation device can have a mode of self configuration or calibration in which defined test signals can be transmitted on the crosstalk-generating channel and the crosstalk-receiving channel.

Claims

1. A method for reducing crosstalk that a first communication signal has imposed on a second communication signal, resulting in a third communication signal comprising the second communication signal and the imposed crosstalk, the method comprising the steps of:

obtaining a sample of the first communication signal;

generating an estimate of the imposed crosstalk in response to processing the sample;

temporally aligning the estimate to the imposed crosstalk; and

reducing the imposed crosstalk in response to applying the temporally aligned estimate to the third communication signal.

2. The method of claim 1, wherein the temporally aligning step comprises timing the estimate to match the imposed crosstalk, and wherein reducing the imposed crosstalk comprises canceling at least some of the imposed crosstalk.

3. The method of claim 1, wherein temporally aligning the estimate to the imposed crosstalk comprises establishing a predetermined phase relationship between the estimate and the imposed crosstalk.

4. The method of claim 3, wherein the predetermined phase relationship comprises a phase difference of approximately 180 degrees.

5. The method of claim 1, wherein temporally aligning the estimate to the imposed crosstalk comprises providing a phase match between the estimate and the imposed crosstalk.

6. The method of claim 1, wherein applying the temporally aligned estimate to the third communication signal comprises generating a fourth communication signal, and

wherein the method further comprises the step of evaluating the reduction of the imposed crosstalk in response to processing the fourth communication signal.

7. The method of claim 1, wherein applying the temporally aligned estimate to the third communication signal comprises generating a fourth communication signal, and

wherein the method further comprises the steps of:

analyzing the fourth communication signal; and

based on the analysis, refining the temporal alignment between the estimate and the imposed crosstalk.

8. The method of claim 1, wherein processing the sample comprises processing the sample based on a parameter, and wherein the method further comprises the step of adjusting the parameter based on an analysis of crosstalk reduction.

9. The method of claim 1, wherein temporally aligning the estimate to the imposed crosstalk comprises delaying the estimate according to a parameter, and wherein the method further comprises the step of adjusting the parameter in response to evaluating the reduced crosstalk.

10. The method of claim 1, further comprising the steps of:

transmitting a test signal on a first channel, operative to carry the first communication signal;

coupling test crosstalk onto a second channel, operative to carry the second communication signal, in response to transmitting the test signal on the first channel; and

setting a parameter of a model in response to analyzing the coupled test crosstalk, wherein processing the sample comprises processing the sample with the model.

11. The method of claim 10, wherein a backplane comprises at least a portion of the first channel and at least a portion of the second channel.

12. The method of claim 1, wherein generating the estimate comprises using an integrated circuit.

13. The method of claim 1, wherein the generating step comprises operating a digital circuit at least one order of magnitude below a channel baud rate.

14. The method of claim 1, further comprising the steps of:

generating test crosstalk in response to transmitting a test signal on a channel; and

adjusting a modeling parameter based on analysis of the generated test crosstalk.

15. A method for reducing communication interference, comprising the steps of:

obtaining a sample of a first communication signal, transmitting on a first communication channel and producing interference on a second communication channel;

generating an estimate of the produced interference in response to processing the sample according to a parameter;

reducing the interference on the second channel in response to applying the generated estimate to the second communication channel;

producing test interference in response to transmitting a test signal on the first communication channel; and

adjusting the parameter in response to analyzing the produced test interference.

16. The method of claim 15, wherein applying the generated estimate to the second communication channel comprises operating an interference compensation device in a first mode, and wherein the step of producing the test interference comprises operating the interference compensation device in a second mode.

17. The method of claim 15, wherein the parameter comprises a modeling parameter, and wherein adjusting the parameter comprises refining the modeling parameter.

18. The method of claim 15, wherein reducing the interference comprises reducing the interference to a level, and wherein the method further comprises the steps of:

generating another estimate of the produced interference based on the adjusted parameter; and

reducing the interference below the level in response to applying the another estimate to the second communication channel.

19. The method of claim 15, wherein generating the estimate comprises using an integrated circuit.

20. The method of claim 15, wherein the generating step comprises operating a digital circuit at least one order of magnitude below a channel baud rate.