Method and apparatus for acquisition and tracking of orthogonal frequency division multiplexing symbol timing, carrier frequency offset and phase noise

• US 8,619,922 B1
• Filed: 10/25/2012
• Issued: 12/31/2013
• Est. Priority Date: 02/04/2002
• Status: Expired due to Term

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Narasimhan, Ravi
• Primary Examiner(s): Torres, Juan A
• Application Number:
  US13/660,580
• Time in Patent Office: 432 Days
• Field of Search: 375/340, 375/346
• US Class Current: 375/340
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 27/2621 Reduction thereof using phase offsets between subcarriers
• CPC Class Codes: H04L 27/2657 Carrier synchronisation
• CPC Class Codes: H04L 27/2659 Coarse or integer frequency offset determination and synchronisation
• CPC Class Codes: H04L 27/2663 Coarse synchronisation, e.g. by correlation
• CPC Class Codes: H04L 27/2671 Time domain
• CPC Class Codes: H04L 27/2675 Pilot or known symbols
• CPC Class Codes: H04L 27/2695 with channel estimation, e.g. determination of delay spread, derivative or peak tracking channel estimation H04L25/0202

Abstract

A method for updating channel estimates in an orthogonal frequency division multiplexing receiver of a wireless local area network includes generating channel estimates for an orthogonal frequency division multiplexing subcarrier as a function of subcarrier index values. The method includes generating a complex number by summing a product of frequency domain signals and the channel estimates for each of the subcarrier index values and dividing the sum by a sum of a squared absolute value of the channel estimate for each of the subcarrier index values. The method includes multiplying the complex number by the channel estimates to generate updated channel estimates.

Claims

1. A wireless network receiver, comprising:

a carrier frequency offset circuit configured to estimate a carrier frequency offset associated with an orthogonal frequency division multiplexing (OFDM) signal received on a communication channel;

a channel estimator configured to generate a first estimate of the communication channel based on the carrier frequency offset; and

an update circuit configured to i) determine a correction factor to compensate for amplitude error and phase error, ii) generate an updated estimate of the communication channel using the first estimate and the correction factor, and iii) adapt, using the correction factor, the carrier frequency offset estimated by the carrier frequency offset circuit.

2. The wireless network receiver of claim 1, wherein the correction factor includes a complex number representation of the first estimate of the communication channel.

3. The wireless network receiver of claim 2, wherein an imaginary component of the complex number representation is used to adapt the carrier frequency offset estimated by the carrier frequency offset circuit.

4. The wireless network receiver of claim 2, wherein the update circuit is configured to generate the correction factor based on a plurality of frequency domain signals associated with the first estimate of the communication channel.

5. The wireless network receiver of claim 2, wherein the channel estimator is configured to generate the updated estimate of the communication channel further based on a product of i) the first estimate of the communication channel and ii) the correction factor.

6. The wireless network receiver of claim 3, wherein the carrier frequency offset circuit is configured to adapt the carrier frequency offset estimated by the carrier frequency offset circuit by determining a product of the imaginary component and an adaptation parameter, and wherein the adaptation parameter is a predetermined constant.

7. The wireless network receiver of claim 6, wherein the update circuit is configured to adapt the carrier frequency offset estimated by the carrier frequency offset circuit by determining a sum of i) the product of the imaginary component and the adaptation parameter, and ii) the estimated carrier frequency offset.

8. A method of operating a wireless network receiver, the method comprising:

estimating a carrier frequency offset associated with an orthogonal frequency division multiplexing (OFDM) signal received on a communication channel;

generating a first estimate of the communication channel based on the carrier frequency offset;

determining a correction factor to compensate for amplitude error and phase error;

generating an updated estimate of the communication channel using the first estimate and the correction factor; and

adapting, using the correction factor, the carrier frequency offset estimated by the carrier frequency offset circuit.

9. The method of claim 8, wherein:

the correction factor includes a complex number representation of the first estimate of the communication channel.

10. The method of claim 9, wherein adapting the carrier frequency offset estimated by the carrier frequency offset circuit comprises using an imaginary component of the complex number representation.

11. The method of claim 9, further comprising generating the complex number representation based on a plurality of frequency domain signals associated with the first estimate of the communication channel.

12. The method of claim 9, further comprising generating the updated estimate further based on a product of the first estimate of the communication channel and the correction factor.

13. The method of claim 10, wherein using the imaginary component comprises determining a product of the imaginary component and an adaptation parameter, and wherein the adaptation parameter is a predetermined constant.

14. The method of claim 13, wherein adapting the carrier frequency offset comprises determining a sum of i) the product of the imaginary component and the adaptation parameter, and ii) the estimated carrier frequency offset.