JAMMER DETECTION AND SUPPRESSION FOR WIRELESS COMMUNICATION

• US 20080143580A1
• Filed: 04/25/2007
• Published: 06/19/2008
• Est. Priority Date: 12/15/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Patel, Shimman, Glazko, Serguei A., Beckman, James Edward
• Granted Patent: US 7,986,922 B2
• Time in Patent Office: Days
• US Class Current: 455/307
• CPC Class Codes: H04B 1/1036 with automatic suppression of narrow band noise or interference, e.g. by using tuneable notch filters H04B1/123 takes precedence; filter circuits H03H
• CPC Class Codes: H04K 3/228 Elimination in the received signal of jamming or of data corrupted by jamming interference suppression in receivers H04B1/10
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01

Abstract

Techniques for detecting and suppressing jammers are described. A receiver may perform post-FFT jammer detection and pre-FFT jammer suppression. The receiver may transform an input signal to obtain a frequency-domain signal and may detect for jammers in the input signal based on the frequency-domain signal. The receiver may determine powers of a plurality of carriers based on the frequency-domain signal and may detect for jammers based on peaks in the powers of these carriers. The receiver may filter the input signal (e.g., with a notch filter) to suppress the detected jammers. Alternatively or additionally, the receiver may perform post-FFT jammer detection and post-FFT jammer suppression. The receiver may determine whether jammer is present on each carrier based on data power and channel power for that carrier. The receiver may modify (e.g., zero out or reduce) the frequency-domain signal on carriers with detected jammers.

Claims

1. An apparatus comprising:

at least one processor configured to transform an input signal to obtain a frequency-domain signal, to detect for jammers in the input signal based on the frequency-domain signal, and to filter the input signal to suppress the detected jammers; and

a memory coupled to the at least one processor.

2. The apparatus of claim 1, wherein the at least one processor is configured to downconvert the input signal by a detected jammer frequency, to filter the downconverted input signal to suppress a jammer at the detected jammer frequency and obtain a filtered signal, and to upconvert the filtered signal by the detected jammer frequency.

3. The apparatus of claim 1, wherein the at least one processor is configured to frequency translate the input signal, to filter the frequency translated input signal to suppress a first jammer at a first frequency and obtain a first filtered signal,

to frequency translate the first filtered signal, to filter the frequency translated first filtered signal to suppress a second jammer at a second frequency and obtain a second filtered signal, and to frequency translate the second filtered signal.

4. The apparatus of claim 1, wherein the at least one processor is configured to filter the input signal based on a notch filter tuned to a detected jammer frequency.

5. The apparatus of claim 1, wherein the at least one processor is configured to transform the input signal based on a first transform mode for jammer detection, and to transform the input signal based on a second transform mode for data demodulation, the first transform mode having higher dynamic range than the second transform mode.

6. The apparatus of claim 1, wherein the at least one processor is configured to determine powers of a plurality of carriers based on the frequency-domain signal, and to detect for jammers based on peaks in the powers of the plurality of carriers.

7. The apparatus of claim 6, wherein the at least one processor is configured to declare a jammer for each peak exceeding a threshold.

8. The apparatus of claim 7, wherein the at least one processor is configured to determine the threshold based on average power for the plurality of carriers.

9. The apparatus of claim 6, wherein the at least one processor is configured to determine frequencies of the detected jammers based on carriers of the peaks.

10. The apparatus of claim 6, wherein the at least one processor is configured to perform interpolation on the peaks and shoulders of the peaks to determine frequencies of the detected jammers.

11. The apparatus of claim 1, wherein the input signal comprises data bursts, wherein the at least one processor is configured to detect for jammers prior to each data burst to be demodulated.

12. The apparatus of claim 1, wherein the at least one processor is configured to enable filtering of the input signal when jammers are detected and to disable filtering of the input signal when jammers are not detected.

13. A method comprising:

transforming an input signal to obtain a frequency-domain signal;

detecting for jammers in the input signal based on the frequency-domain signal; and

filtering the input signal to suppress the detected jammers.

14. The method of claim 13, wherein the detecting for jammers in the input signal comprises

determining powers of a plurality of carriers based on the frequency-domain signal, and

detecting for jammers based on peaks in the powers of the plurality of carriers.

15. The method of claim 13, wherein the filtering the input signal to suppress the detected jammers comprises filtering the input signal with a notch filter to suppress the detected jammers.

16. An apparatus comprising:

means for transforming an input signal to obtain a frequency-domain signal;

means for detecting for jammers in the input signal based on the frequency-domain signal; and

means for filtering the input signal to suppress the detected jammers.

17. The apparatus of claim 16, wherein the means for detecting for jammers in the input signal comprises

means for determining powers of a plurality of carriers based on the frequency-domain signal, and

means for detecting for jammers based on peaks in the powers of the plurality of carriers.

18. The apparatus of claim 16, wherein the means for filtering the input signal to suppress the detected jammers comprises means for filtering the input signal with a notch filter to suppress the detected jammers.

19. An apparatus comprising:

at least one processor configured to transform an input signal to obtain a frequency-domain signal, to detect for jammers in the input signal based on the frequency-domain signal, and to modify the frequency-domain signal on carriers with detected jammers; and

a memory coupled to the at least one processor.

20. The apparatus of claim 19, wherein the at least one processor is configured to zero out the frequency-domain signal on each carrier with a detected jammer.

21. The apparatus of claim 19, wherein the at least one processor is configured to reduce the frequency-domain signal on each carrier with a detected jammer.

22. The apparatus of claim 19, wherein the at least one processor is configured to reduce log likelihood ratios (LLRs) for each carrier with a detected jammer.

23. The apparatus of claim 19, wherein the at least one processor is configured to determine data power for each of a plurality of carriers, to determine channel power for each of the plurality of carriers, and to determine whether jammer is present on each of the plurality of carriers based on the data power and the channel power for the carrier.

24. The apparatus of claim 23, wherein the at least one processor is configured to declare a jammer if the data power exceeds the channel power by a predetermined amount.

25. The apparatus of claim 23, wherein the at least one processor is configured to obtain received symbols for the plurality of carriers in multiple symbol periods, and to filter power of received symbols for each carrier across the multiple symbol periods to obtain the data power for the carrier.

26. The apparatus of claim 23, wherein the at least one processor is configured to derive channel gain estimates for the plurality of carriers in multiple symbol periods, and to filter power of channel gain estimates for each carrier across the multiple symbol periods to obtain the channel power for the carrier.

27. The apparatus of claim 19, wherein the at least one processor is configured to determine data power for each of a plurality of carriers, to determine noise power for each of the plurality of carriers, and to determine whether jammer is present on each of the plurality of carriers based on the data power and the noise power for the carrier.

28. The apparatus of claim 19, wherein the at least one processor is configured to determine whether or not to perform jammer detection and suppression based on a code rate used for transmitted data.

29. A method comprising:

transforming an input signal to obtain a frequency-domain signal;

detecting for jammers in the input signal based on the frequency-domain signal; and

modifying the frequency-domain signal on carriers with detected jammers.

30. The method of claim 29, wherein the detecting for jammers in the input signal comprises

determining data power for each of a plurality of carriers,

determining channel power for each of the plurality of carriers, and

determining whether jammer is present on each of the plurality of carriers based on the data power and the channel power for the carrier.

31. The method of claim 29, wherein the modifying the frequency-domain signal comprises zeroing out the frequency-domain signal on each carrier with a detected jammer.

32. An apparatus comprising:

means for transforming an input signal to obtain a frequency-domain signal;

means for detecting for jammers in the input signal based on the frequency-domain signal; and

means for modifying the frequency-domain signal on carriers with detected jammers.

33. The apparatus of claim 32, wherein the means for detecting for jammers in the input signal comprises

means for determining data power for each of a plurality of carriers,

means for determining channel power for each of the plurality of carriers, and

means for determining whether jammer is present on each of the plurality of carriers based on the data power and the channel power for the carrier.

34. The apparatus of claim 32, wherein the means for modifying the frequency-domain signal comprises means for zeroing out the frequency-domain signal on each carrier with a detected jammer.