Channel estimator for updating channel estimates and carrier frequency offsets

• US 8,929,487 B1
• Filed: 12/30/2013
• Issued: 01/06/2015
• Est. Priority Date: 03/05/2001
• Status: Expired due to Fees

• Current Assignee: Marvell International 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:
  US14/143,722
• Time in Patent Office: 372 Days
• Field of Search: 375/340
• 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 channel estimator for a wireless network receiver. The channel estimator includes a plurality of first circuits, each of the plurality of first circuits configured to multiply a respective channel estimate by a corresponding frequency domain signal, wherein the channel estimates correspond to an orthogonal frequency division multiplexing signal received by the wireless network receiver. A second circuit is configured to output a sum of results of multiplying the respective channel estimates by the corresponding frequency domain signals. A third circuit is configured to calculate, based on the sum, a correction factor, wherein the correction factor corresponds to a complex number representation of the respective channel estimates. A fourth circuit is configured to output, based on the correction factor and a previously calculated channel estimate, an updated channel estimate corresponding to the orthogonal frequency division multiplexing signal received by the wireless network receiver.

Claims

1. A channel estimator for a wireless network receiver, the channel estimator comprising:

a plurality of first circuits, each of the plurality of first circuits configured to multiply a respective channel estimate by a corresponding frequency domain signal, wherein the channel estimates correspond to an orthogonal frequency division multiplexing signal received by the wireless network receiver;

a second circuit configured to output a sum of results of multiplying the respective channel estimates by the corresponding frequency domain signals;

a third circuit configured to calculate, based on the sum, a correction factor, wherein the correction factor corresponds to a complex number representation of the respective channel estimates; and

a fourth circuit configured to output, based on the correction factor and a previously calculated channel estimate, an updated channel estimate corresponding to the orthogonal frequency division multiplexing signal received by the wireless network receiver.

2. The channel estimator of claim 1, wherein the channel estimates correspond to respective subcarriers of the orthogonal frequency division multiplexing signal received by the wireless network receiver.

3. The channel estimator of claim 1, wherein outputting the updated channel estimate includes multiplying the correction factor by the previously calculated channel estimate.

4. The channel estimator of claim 1, further comprising a plurality of fifth circuits, each of the plurality of fifth circuits configured to calculate absolute values of the respective channel estimates.

5. The channel estimator of claim 1, further comprising a fifth circuit configured to calculate, based on the correction factor, a carrier frequency offset associated with the orthogonal frequency division multiplexing signal received by the wireless network receiver.

6. The channel estimator of claim 3, wherein multiplying the correction factor by the previously calculated channel estimate compensates for common amplitude and phase error, caused by frequency offsets and phase noise, in the previously calculated channel estimate.

7. The channel estimator of claim 4, wherein, to calculate the correction factor, the third circuit is configured to calculate the correction factor based on the sum and further based on the absolute values.

8. The channel estimator of claim 5, wherein, to calculate the carrier frequency offset, the fifth circuit is configured to (i) determine an imaginary component of the correction factor, (ii) multiply the imaginary component of the correction factor by a predetermined constant, and (iii) add a previously calculated carrier frequency offset to a result of multiplying the imaginary component of the correction factor by the predetermined constant.

9. A method for operating a channel estimator for a wireless network receiver, the method comprising:

multiplying a plurality of respective channel estimates by a corresponding frequency domain signal, wherein the channel estimates correspond to an orthogonal frequency division multiplexing signal received by the wireless network receiver;

outputting a sum of results of multiplying the respective channel estimates by the corresponding frequency domain signals;

calculating, based on the sum, a correction factor, wherein the correction factor corresponds to a complex number representation of the respective channel estimates; and

outputting, based on the correction factor and a previously calculated channel estimate, an updated channel estimate corresponding to the orthogonal frequency division multiplexing signal received by the wireless network receiver.

10. The method of claim 9, wherein the channel estimates correspond to respective subcarriers of the orthogonal frequency division multiplexing signal received by the wireless network receiver.

11. The method of claim 9, wherein outputting the updated channel estimate includes multiplying the correction factor by the previously calculated channel estimate.

12. The method of claim 9, further comprising calculating absolute values of the respective channel estimates.

13. The method of claim 9, further comprising calculating, based on the correction factor, a carrier frequency offset associated with the orthogonal frequency division multiplexing signal received by the wireless network receiver.

14. The method of claim 11, wherein multiplying the correction factor by the previously calculated channel estimate compensates for common amplitude and phase error, caused by frequency offsets and phase noise, in the previously calculated channel estimate.

15. The method of claim 12, wherein calculating the correction factor includes calculating the correction factor based on the sum and further based on the absolute values.

16. The method of claim 13, wherein calculating the carrier frequency offset includes (i) determining an imaginary component of the correction factor, (ii) multiplying the imaginary component of the correction factor by a predetermined constant, and (iii) adding a previously calculated carrier frequency offset to a result of multiplying the imaginary component of the correction factor by the predetermined constant.