METHODS AND SYSTEMS FOR COMPUTING A MINIMUM VARIANCE UNBIASED ESTIMATOR OF CARRIER AND SAMPLING CLOCK FREQUENCY

• US 20080247481A1
• Filed: 04/07/2008
• Published: 10/09/2008
• Est. Priority Date: 04/06/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Olympus Corporation
• Inventors: HEIDARI-BATENI, GHOBAD, IONESCU, DUMITRU MIHAI, AMANULLAH, ABU
• Granted Patent: US 8,036,290 B2
• Time in Patent Office: Days
• 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 computing a minimum variance unbiased estimator comprising:

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.

2. The method of claim 1, wherein the unique minimum variance unbiased estimator is applied for a carrier relative frequency offset.

3. The method of claim 1, wherein the unique minimum variance unbiased estimator is applied for a sampling clock relative frequency offset.

4. The method of claim 1, wherein the unique minimum variance unbiased estimator is applied using a symmetric representation of frequency domain signal.

5. The method of claim 4, wherein the a symmetric representation of frequency domain signal comprises a conjugate symmetric component.

6. The method of claim 1, wherein the unique minimum variance unbiased estimator is applied using an asymmetric representation of frequency domain signal.

7. The method of claim 1, wherein the differential phase metric is calculated at a pilot tone.

8. The method of claim 1, wherein the differential phase metric is calculated between two consecutive symbols.

9. The method of claim 1, wherein the differential phase metric is calculated between symbols sent in the same frequency band.

10. The method of claim 1, further comprising calculating a differential phase metric at all pilot tones used to estimate the carrier and sampling clock frequency.

11. A system for computing a minimum variance unbiased estimator comprising:

an antenna;

a processor, coupled to the antenna; and

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

receive a first OFDM signal at a pilot tone;

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

determine a differential phase metric between the first OFDM signal and the second OFDM signal.

12. The system of claim 11, wherein the instructions are further configured to cause the processor to apply the unique minimum variance unbiased estimator for a carrier relative frequency offset.

13. The system of claim 11, wherein the instructions are further configured to cause the processor to apply the unique minimum variance unbiased estimator for a sampling clock relative frequency offset.

14. The system of claim 11, wherein the instructions are further configured to cause the processor to apply the unique minimum variance unbiased estimator using a symmetric representation of frequency domain signal.

15. The system of claim 14, wherein the a symmetric representation of frequency domain signal comprises a conjugate symmetric component.

16. The system of claim 11, wherein the instructions are further configured to cause the processor to apply the unique minimum variance unbiased estimator using an asymmetric representation of frequency domain signal.

17. The system of claim 11, wherein the instructions are further configured to cause the processor to calculate the differential phase metric at a pilot tone.

18. The system of claim 11, wherein the instructions are further configured to cause the processor to calculate the differential phase metric between two consecutive symbols.

19. The system of claim 11, wherein the instructions are further configured to cause the processor to calculate the differential phase metric between symbols sent in the same frequency band.

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