Method and system for channel equalization and crosstalk estimation in a multicarrier data transmission system

• US 20060146945A1
• Filed: 01/06/2005
• Published: 07/06/2006
• Est. Priority Date: 01/06/2005
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Hong Kong Applied Science And Technology Research Institute Co., Ltd.
• Inventors: Ng, Francis Man-Lung, Leung, Pak Hei Matthew, Fung, Tin-Yau, Tang, Eugene Yuk-Yin, Chow, Jacky S., Luk, King-Fuk
• Granted Patent: US 7,561,627 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04B 3/487 Testing crosstalk effects
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 25/03159 operating in the frequency domain H04L25/03165, H04L25/03178 take precedence

Abstract

Improved techniques for concurrent channel equalization and far-end crosstalk channel compensation (e.g., estimation and/or cancellation) in a multicarrier data transmission system are disclosed. The improved techniques can produce coefficients for an electronic filter that provide channel equalization and for an electronic filter that provides cancellation of the far-end crosstalk. These coefficients can be initially trained and then subsequently updated during data transmission. Optionally, common coefficient determination resources can be utilized for both far-end crosstalk and near-end crosstalk purposes. These improved techniques are particularly suitable for use with a digital multicarrier communication system having multiple-input multiple-output systems.

Claims

1. A multicarrier data transmission system, comprising:

a FFT unit that receives incoming time-domain symbols that have been transmitted through a communication medium and outputs the incoming symbol in frequency-domain;

an adaptive channel equalizer that produces a noise estimate, the noise estimate pertaining to at least inter-carrier interference and inter-symbol interference;

a subtractor operatively connected to subtract the noise estimate from the incoming frequency-domain symbols to produce channel adjusted symbols;

a FEXT unit operatively connected to adaptively determine FEXT channel coefficients and to reduce FEXT from the channel adjusted symbols in accordance with the FEXT channel coefficients so as to produce desired symbols; and

a symbol detector for examining the desired symbols to determine detected symbols.

2. A multicarrier data transmission system as recited in claim 1, wherein said FEXT unit serves to compensate for not only far-end crosstalk but also frequency equalization or channel attenuation.

3. A multicarrier data transmission system as recited in claim 1, wherein said multicarrier data transmission system further comprises:

an adaptive update unit that performs an update algorithm that causes modification to both the FEXT channel coefficients and the channel estimate.

4. A multicarrier data transmission system as recited in claim 3, wherein the channel estimate is based on channel coefficients, and

wherein said adaptive update unit causes the FEXT channel coefficients and the channel coefficients to be jointly optimized.

5. A multicarrier data transmission system as recited in claim 4, said multicarrier data transmission system further comprises:

a subtractor that produces an error signal due to unwanted interference, and

wherein said adaptive update unit causes the FEXT channel coefficient and the channel coefficients to be jointly updated based on the error signal.

6. A multicarrier data transmission system as recited in claim 5, wherein said FEXT unit includes a FEXT estimator and a FEXT canceller.

7. A multicarrier data transmission system as recited in claim 6, wherein said FEXT estimator and said FEXT canceller share a substantial portion of their circuitry.

8. A multicarrier data transmission system as recited in claim 4, wherein said multicarrier data transmission system is operable in a training mode and a data mode, and

wherein said adaptive channel equalizer and said FEXT unit are both operable in the training mode or the data mode so that said adaptive update unit causes the FEXT channel coefficient and the channel coefficients to be jointly updated in either the training mode or the data mode.

9. A multicarrier data transmission system as recited in claim 3, wherein said multicarrier data transmission system is operable in a training mode and a data mode, and

wherein said multicarrier data transmission system further comprises:

a first FEXT subtractor operable in the training mode to produce a first error signal due to unwanted interference;

a second FEXT subtractor operable in the data mode to produce a second error signal based on differences between the desired symbols and the detected symbols; and

an adaptive update unit that performs an update algorithm that causes modification to both the FEXT channel coefficients and the channel estimate based on one of the first error signal and the second error signal.

10. A multicarrier data transmission system as recited in claim 9, wherein said multicarrier data transmission system further comprises:

a selector operatively connected to said first FEXT subtractor and said second FEXT subtractor, said selector controllably supplying one of the first error signal and the second error signal to said adaptive update unit.

11. A multicarrier data transmission system as recited in claim 9, wherein said multicarrier data transmission system further comprises:

a first selector operatively connected to said first FEXT subtractor and said FEXT unit, said first selector controllably supplying the channel adjusted symbols to said first FEXT subtractor or said FEXT unit; and

a second selector operatively connected to said first FEXT subtractor and said second FEXT subtractor, said second selector controllably supplying one of the first error signal and the second error signal to said adaptive update unit.

12. A multicarrier data transmission system as recited in claim 9, wherein said FEXT unit serves to compensate for not only far-end crosstalk but also frequency equalization or channel attenuation.

13. A multicarrier data transmission system as recited in claim 1, wherein said multicarrier data transmission system further comprises a NEXT canceller, said NEXT canceller using at least at portion of said FEXT unit, thereby sharing resources.

14. A multicarrier data transmission system as recited in claim 1, wherein said multicarrier data transmission system operates in a multiple-inputs multiple-outputs environment.

15. A multicarrier data transmission system as recited in claim 1, wherein said adaptive channel equalizer produces the noise estimate based on the incoming time-domain symbols.

16. A multicarrier data transmission system as recited in claim 1, wherein the FEXT channel coefficients include direct and cross channel coefficients.

17. A multicarrier data transmission system, comprising:

a FFT unit that receives incoming time-domain symbols that have been transmitted through a communication medium and outputs incoming frequency-domain symbols;

an adaptive channel equalizer that produces a noise estimate, the noise estimate pertaining to at least inter-carrier interference and inter-symbol interference;

a subtractor operatively connected to subtract the channel estimate from the incoming frequency-domain symbols to produce channel adjusted symbols;

a FEXT estimator operatively connected to adaptively determine FEXT channel coefficients;

a descaling unit operatively connected to scale the channel adjusted symbols to produce desired symbols; and

a symbol detector for examining the desired symbols to determine detected symbols,

wherein the FEXT channel coefficients are used to produce scaling data, and wherein said descaling unit operates to scale the channel adjusted symbols in accordance with the scaling data.

18. A multicarrier data transmission system as recited in claim 17, wherein the FEXT channel coefficients are used to compensate for not only far-end crosstalk but also frequency equalization or channel attenuation.

19. A multicarrier data transmission system as recited in claim 17, wherein said multicarrier data transmission system further comprises:

an adaptive update unit that performs an update algorithm that causes modification to both the FEXT channel coefficients and the channel estimate.

20. A multicarrier data transmission system as recited in claim 19, wherein the channel estimate is based on channel coefficients, and

wherein said adaptive update unit causes the FEXT channel coefficients and the channel coefficients to be jointly updated.

21. A multicarrier data transmission system as recited in claim 20, wherein said multicarrier data transmission system further includes a FEXT compensation unit that communicates with a precoder at a transmitter to provide FEXT compensation to symbols prior to transmission.

22. A multicarrier data transmission system as recited in claim 21, wherein said multicarrier data transmission system further includes a rotation and scaling unit that communicates with the precoder at the transmitter to provide rotation and/or scaling to symbols prior to transmission.

23. A method for operating a multicarrier data transmission system having a training mode and a data transfer mode, the multicarrier data transmission system including a far-end crosstalk unit and a channel equalizer, said method comprising:

placing the multicarrier data transmission system in the training mode;

receiving training symbols that have been transmitted over a transmission sequence; and

processing the received training symbols to concurrently train the far-end crosstalk unit and the channel equalizer.

24. A method as recited in claim 23, wherein said method further comprises:

thereafter placing the multicarrier data transmission system in the data transfer mode;

receiving incoming data symbols via a communication channel; and

determining an error signal associated with detection of the incoming data symbols.

25. A method as recited in claim 24, wherein said method further comprises:

determining update parameters for the far-end crosstalk unit and the channel equalizer based on the error signal; and

updating the far-end crosstalk unit and the channel equalizer based on the update parameters.

26. A method as recited in claim 25, wherein said determining of the update parameters comprises:

determining a first set of update coefficients for the far-end crosstalk unit;

determining a second set of update coefficients for the channel equalizer,

wherein said determining of the first set of update coefficients and said determining of the second set of update coefficients are concurrently performed.

27. A method as recited in claim 26, wherein said updating of the far-end crosstalk unit and the channel equalizer comprises:

updating the far-end crosstalk unit in accordance with the first set of update coefficients; and

updating the channel equalizer in accordance with the second set of update coefficients.

28. A method as recited in claim 24, wherein said method further comprises:

determining update parameters for the far-end crosstalk unit and the channel equalizer based on the error signal; and

adaptively updating the far-end crosstalk unit and the channel equalizer based on the update parameters.