Adaptive channel estimation for orthogonal frequency division multiplexing systems or the like

• US 20040120428A1
• Filed: 03/05/2003
• Published: 06/24/2004
• Est. Priority Date: 12/18/2002
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Pudeyev, Andrey V., Maltsev, Alexander A., Sadri, Ali S.
• Granted Patent: US 7,394,873 B2
• Time in Patent Office: Days
• US Class Current: 375/341
• CPC Class Codes: H04L 25/0216 with estimation of channel length
• CPC Class Codes: H04L 25/0218 with detection of nulls
• CPC Class Codes: H04L 25/022 of frequency response
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 25/025 using least-mean-square [LMS] method
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01

Abstract

Briefly, in accordance with one embodiment of the invention, a channel estimator may be adapted to provide a channel estimate based at least in part on an estimated delay spread. The channel estimator may be adapted to provide a more accurate channel estimation in the event of a lower estimated delay spread. In one embodiment, the channel estimator provides a frequency domain channel estimate, and in another embodiment the channel estimator provides a time domain channel estimate.

Claims

1. An apparatus, comprising:

a frequency domain smoother to provide a frequency domain channel estimate based at least in part on a least square channel estimate and an estimated delay spread.

2. An apparatus as claimed in claim 1, further comprising a least square estimator to provide a least square channel estimate in response to a received training sequence, and a delay spread estimator to determine an estimated delay spread in response to the received training sequence.

3. An apparatus as claimed in claim 1, wherein said frequency domain smoother is adapted to provide the frequency domain channel estimate based at least on part on a Hamming window.

4. An apparatus as claimed in claim 1, wherein said frequency domain smoother is adapted to provide the frequency domain channel estimate based at least in part on an estimated delay spread of less than or equal to about 200 nanoseconds.

5. An apparatus, comprising:

a maximum likelihood estimator to provide a maximum likelihood channel estimate in response to a received training sequence; and

wherein said maximum likelihood estimator is adapted to provide a time domain channel estimate based at least in part on an estimated delay spread.

6. An apparatus as claimed in claim 5, further comprising a delay spread estimator to determine an estimated delay spread in response to the received training sequence.

7. An apparatus as claimed in claim 5, wherein said maximum likelihood estimator is adapted to determine a number of channel coefficients to provide the time domain channel estimate based at least in part on the estimated delay spread.

8. An apparatus as claimed in claim 5, wherein said maximum likelihood estimator is adapted to provide the time domain channel estimate based at least in part on an estimated delay spread of less than or equal to 200 nanoseconds.

9. An apparatus, comprising:

a maximum likelihood estimator to provide a maximum likelihood channel estimate in response to a received training sequence; and

wherein said maximum likelihood estimator is adapted to provide a time domain channel estimate based at least in part on an estimated number and delays of significant rays.

10. An apparatus as claimed in claim 9, further comprising a significant rays estimator to determine the number and delays of the significant rays in response to the received training sequence.

11. An apparatus as claimed in claim 9, wherein said maximum likelihood estimator is adapted to determine a number and delays of significant channel coefficients to provide the time domain channel estimate.

12. A method, comprising:

determining a delay spread estimate; and

providing a channel estimate determined at least in part on the delay spread estimate.

13. A method as claimed in claim 12, said providing a channel estimate including providing a time domain channel estimate.

14. A method as claimed in claim 12, said providing a channel estimate including providing a frequency domain channel estimate.

15. A method as claimed in claim 12, wherein said providing a channel estimate is based at least on part on a Hamming window.

16. A method as claimed in claim 12, wherein said adapting is based at least in part on an estimated delay spread of less than or equal to 200 nanoseconds.

17. An article comprising a storage medium having stored thereon instructions that, when executed by a computing platform, result in adapting a channel estimate to an estimated delay spread by:

determining a delay spread estimate; and

providing a channel estimate determined at least in part on the delay spread estimate.

18. An article as claimed in claim 17, wherein the instructions, when executed, further result in providing a time domain channel estimate.

19. An article as claimed in claim 17, wherein the instructions, when executed, further result in providing a frequency domain channel estimate.

20. An article as claimed in claim 17, wherein the instructions, when executed, further result in basing the channel estimate at least on part on a Hamming window.

21. An article as claimed in claim 17, wherein the instructions, when executed, further result in basing said adjusting at least in part on an estimated delay spread of less than or equal to about 200 nanoseconds.

24. An apparatus as claimed in claim 21, wherein said channel estimator is adapted to provide the channel estimate based at least on part on a Hamming window.

25. An apparatus as claimed in claim 21, wherein said channel estimator is adapted to provide the channel estimate based at least in part on an estimated delay spread of less than or equal to about 200 nanoseconds.

22. An apparatus, comprising:

a channel estimator to provide a channel estimate in response to a received training sequence;

a delay spread estimator to determine an estimated delay spread in response to the received training sequence;

wherein said channel estimator is adapted to provide the channel estimate based at least in part on the estimated delay spread; and

a non-volatile memory device in which at least one of the channel estimate and the estimated delay spread may be stored.

23. An apparatus as claimed in claim 22, wherein said channel estimator is adapted to provide a more accurate channel estimate with a shorter estimated delay spread.