Adaptive channel equalizer for wireless system

• US 20050141657A1
• Filed: 12/30/2003
• Published: 06/30/2005
• Est. Priority Date: 12/30/2003
• Status: Abandoned Application

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Pudeyev, Andrey V., Maltsev, Alexander A., Rubtsov, Alexey E., Sadri, Ali S.
• Application Number:
  US10/750,064
• Publication Number:
  US 20050141657A1
• Time in Patent Office: Days
• US Class Current: 375/346
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 2025/03522 Frequency domain
• CPC Class Codes: H04L 25/0202 Channel estimation
• CPC Class Codes: H04L 25/03159 operating in the frequency domain H04L25/03165, H04L25/03178 take precedence

Abstract

Various embodiments are described for an adaptive channel equalizer.

Claims

1. An apparatus comprising:

an averaging circuit adapted to provide an averaged channel estimate by performing a time domain averaging and frequency domain averaging on one or more received inputs; and

an equalizer to equalize a received multicarrier symbol based on the averaged channel estimate.

2. The apparatus of claim 1 wherein the averaging circuit is adapted to provide an averaged channel estimate by performing a time domain averaging and frequency domain averaging on one or more received channel estimates.

3. The apparatus of claim 1 wherein the averaging circuit comprises:

a time domain averaging block adapted to perform time domain averaging on a plurality of received channel estimates to generate a time domain averaged channel estimate on a per subcarrier basis; and

a frequency domain averaging block adapted to perform frequency domain averaging on a received time domain averaged channel estimate.

4. The apparatus of claim 3 wherein the frequency domain averaging block generates frequency domain averaged channel estimates that are used to update coefficients of the equalizer.

5. The apparatus of claim 3 wherein the time domain averaging block is adapted to perform time domain averaging on a plurality of received channel estimates to generate a time domain averaged channel estimate on a per subcarrier basis using a moving average.

6. The apparatus of claim 3 wherein the time domain averaging block is adapted to perform time domain averaging on a plurality of received channel estimates to generate a time domain averaged channel estimate on a per subcarrier basis using block averaging.

7. The apparatus of claim 1 and further comprising a coarse channel estimator to generate a coarse channel estimate to be input to the averaging circuit.

8. The apparatus of claim 7 wherein the coarse channel estimator is adapted to generate a coarse channel estimate as the received symbol divided by a replica of a transmitted symbol, per subcarrier.

9. The apparatus of claim 1 wherein the equalizer comprises an adaptive equalizer.

10. The apparatus of claim 1 wherein the multicarrier symbol comprises an OFDM symbol.

11. An apparatus comprising:

an equalizer to equalize a received symbol based on a fine channel estimate;

a mapping block to provide a replica of a transmitted symbol;

a coarse channel estimator to receive a symbol replica from the mapping block and a corresponding received symbol, the coarse channel estimator to generate a coarse channel estimate;

an averaging circuit adapted to perform time domain averaging on a plurality of coarse channel estimates to generate a time domain averaged channel estimate, and to perform frequency domain averaging on the time domain averaged channel estimate to generate the fine channel estimate.

12. The apparatus of claim 11 wherein the averaging circuit comprises a time domain averaging block and a frequency domain averaging block.

13. The apparatus of claim 11 wherein the received symbol comprises a multicarrier symbol, and the replica symbol comprises a replica of a corresponding transmitted multicarrier symbol.

14. The apparatus of claim 13 wherein the received multicarrier symbol comprises an OFDM symbol.

15. A method comprising:

performing a time domain averaging on one or more received inputs to generate a time domain averaged channel estimate on a per subcarrier basis;

performing a frequency domain averaging on the time domain averaged channel estimate to generate a fine channel estimate; and

updating equalizer coefficients based upon the fine channel estimate.

16. The method of claim 15 wherein the performing a time domain averaging comprises:

generating a coarse channel estimate based on a received multicarrier symbol and a generated replica of the corresponding transmitted multicarrier symbol; and

performing a time domain averaging on a plurality of coarse channel estimates on a per subcarrier basis to generate a time domain averaged channel estimate.

17. The method of claim 16 wherein the generating a coarse channel estimate comprises:

generating a replica of a transmitted multicarrier symbol; and

generating a coarse channel estimate by dividing a received multicarrier symbol by the generated replica of the corresponding transmitted multicarrier symbol.

18. A method comprising:

calculating an initial channel estimate based upon one or more received training symbols;

setting equalizer coefficients based upon the initial channel estimate;

performing both time domain averaging and frequency domain averaging on a subsequent calculated channel estimate to generate an averaged channel estimate; and

updating the equalizer coefficients based upon the averaged channel estimate.