Methods and systems for diversity combining of synchronization statistics in OFDM systems

• US 8,031,789 B2
• Filed: 04/07/2008
• Issued: 10/04/2011
• Est. Priority Date: 04/06/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Olympus Corporation
• Inventors: Ionescu, Dumitru Mihai, Amanullah, Abu, Heidari-Bateni, Ghobad
• Primary Examiner(s): PHU, PHUONG M
• Application Number:
  US12/099,017
• Publication Number:
  US 20090067532A1
• Time in Patent Office: 1,275 Days
• Field of Search: 375/260, 375/267, 375/347, 375/349, 375/354, 375/356, 375/371, 375/206, 375/208, 455/500, 455/101
• US Class Current: 375/260
• CPC Class Codes: H04J 11/0066 of narrowband interference narrowband interference reduction H04B1/1036
• CPC Class Codes: H04L 27/2657 Carrier synchronisation
• CPC Class Codes: H04L 27/2675 Pilot or known symbols
• CPC Class Codes: H04L 27/2691 involving interference determination or cancellation

Abstract

Various embodiments of the systems and methods described herein may be used to compute a minimum variance unbiased estimator by receiving a first OFDM signal at a pilot tone, receiving a second OFDM signal sent in the same frequency band and determining a differential phase metric between the first OFDM signal and the second OFDM signal. In some embodiments, the differential phase metric may be used to diversity combine synchronization statistics. In various embodiments, the differential phase metric may be used to detect a narrow-band interference.

Claims

1. A method of diversity combining of synchronization statistics comprising:

determining a plurality of diversity observations in a diversity system by calculating a plurality of differential phase metrics at a plurality of pilot tones, the differential phase metric calculated by;

receiving a first OFDM signal at a pilot tone;

receiving a second OFDM signal sent in the same frequency band; and

determining a differential phase metric between the first OFDM signal and the second OFDM signal;

collecting diversity observations on the same pilot tones during a number of uncorrelated frequency hops; and

combining the diversity observations.

2. The method of claim 1, further comprising collecting diversity observations on the same pilot tones.

3. The method of claim 2, wherein the collecting diversity observations on the same pilot tones occurs during a number of uncorrelated diversity branches.

4. The method of claim 3, wherein the uncorrelated diversity branches comprise a number of frequency hops.

5. The method of claim 1, further comprising combining diversity observations of a differential synchronization statistic.

6. The method of claim 1, wherein the steps are repeated during a packet.

7. The method of claim 1, further comprising correcting a local oscillator'"'"'s frequency based on estimated synchronization parameters.

8. The method of claim 1, further comprising correcting demodulated samples based on estimated synchronization parameters.

9. The method of claim 1, further comprising combining signal estimates based on asymmetric observables.

10. The method of claim 1, further comprising repeating the steps at all pilot tones used to estimate the carrier and sampling clock frequency.

11. A system for diversity combining of synchronization statistics comprising:

a first antenna;

a second antenna;

a processor, coupled to the antennas; and

a memory, coupled to the processor and configured to store instructions causing the processor to;

determine a plurality of diversity observations in a diversity system by calculating a plurality of differential phase metrics at a plurality of pilot tones, the differential phase metric calculated by;

receive a first OFDM signal at a pilot tone;

receiving a second OFDM signal sent in the same frequency band; and

determining a differential phase metric between the first OFDM signal and the second OFDM signal; and

collect diversity observations on the same pilot tones during a number of uncorrelated frequency hops; and

combining the diversity observations.

12. The system of claim 11, wherein the instructions are further configured to cause the processor to collect diversity observations on the same pilot tones.

13. The system of claim 12, wherein the instructions are further configured to cause the processor to collect diversity observations on the same pilot tones occurs during a number of uncorrelated diversity branches.

14. The system of claim 13, wherein the uncorrelated diversity branches comprise a number of frequency hops.

15. The system of claim 11, wherein the instructions are further configured to cause the processor to combine diversity observations of a differential synchronization statistic.

16. The system of claim 11, wherein the steps are repeated during a packet.

17. The system of claim 11, wherein the instructions are further configured to cause the processor to correct a local oscillator'"'"'s frequency based on estimated synchronization parameters.

18. The system of claim 11, wherein the instructions are further configured to cause the processor to correct demodulated samples based on estimated synchronization parameters.

19. The system of claim 11, wherein the instructions are further configured to cause the processor to combine signal estimates based on asymmetric observables.

20. The system of claim 11, wherein the instructions are further configured to cause the processor to repeat the steps at all pilot tones used to estimate the carrier and sampling clock frequency.