SYSTEM AND METHOD FOR WIRELESS CHANNEL SENSING

• US 20080165680A1
• Filed: 03/02/2007
• Published: 07/10/2008
• Est. Priority Date: 01/07/2007
• Status: Active Grant

• Current Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Inventors: Chang, Soo-Young
• Granted Patent: US 8,077,676 B2
• Time in Patent Office: Days
• US Class Current: 370/230
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0062 Avoidance of ingress interference, e.g. ham radio channels

Abstract

System and method for wireless channel sensing. According to an embodiment, the present invention provides a method of determining band availability for a WRAN. The method includes receiving wirelessly analog signals within a predetermined range of frequencies. The method also includes converting the analog signals to digital signals. The digital signals are characterized in a frequency domain. The method additionally includes determining a plurality of signal strength levels associated with the digital signals at a plurality of frequencies. Furthermore, the method includes comparing the plurality of signal strength levels to reference levels at the plurality of frequencies. Moreover, the method includes determining band availability for wireless communication at the predetermined range of frequencies.

Claims

1. A method of determining band availability for a WRAN network comprising:

receiving wirelessly analog signals within a predetermined range of frequencies;

modifying the analog signals to provide digital signals, the digital signals being characterized in a frequency domain;

determining a plurality of signal spectral amplitudes associated with the digital signals at a plurality of frequencies;

comparing the plurality of signal spectral amplitudes to reference levels at the plurality of frequencies; and

determining a band availability for wireless communication at the predetermined range of frequencies.

2. The method of claim 1 wherein the comparing comprises determining a correlation between the plurality of signal spectral amplitudes and the reference levels.

3. The method of claim 1 further comprising averaging analog signals.

4. The method of claim 1 further comprising providing reference levels based on a plurality of characteristics associated with a television broadcast frequency.

5. The method of claim 1 further comprising determining a signal type associated with the digital signals.

6. The method of claim 1 further comprising selecting the predetermined range of frequencies.

7. The method of claim 1 wherein the comparing the plurality of signal strength levels comprises:

providing a signal indicating that a band is unavailable if any one of the plurality of signal strength levels is greater or equal to the reference levels at a corresponding frequency.

8. The method of claim 1 further comprising shifting the analog signals.

9. The method of claim 1 wherein the plurality of frequencies includes at least five frequencies.

10. The method of claim 1 wherein the predetermined range of frequencies is associated to a plurality of television channels.

11. The method of claim 1 further comprising selecting the plurality of frequencies.

12. The method of claim 1 wherein the plurality of frequencies includes a pilot audio frequency and a pilot video frequency.

13. The method of claim 1 wherein the wireless analog signals comprises television broadcasting signals.

14. The method of claim 1 wherein the predetermined range has a bandwidth of approximately six megahertz.

15. The method of claim 1 wherein the predetermined range has a bandwidth of approximately 200 kHz.

16. The method of claim 1 wherein the predetermined range is associated with Part 74 devices.

17. The method of claim 1 further comprising filtering the analog signals.

18. The method of claim 1 wherein the modifying the analog signals comprises:

converting analog signals to time-domain signals;

converting time-domain signals to digital signals using a fast Fourier transform.

19. A system for determining availability of wireless communication links, the system comprising:

an antenna for wirelessly receiving analog signals, the analog signals being within a predetermined range of frequencies, the analog signals being associated with a time-domain;

a converting component for converting the analog signals to a first plurality of digital signals, the first plurality of digital signals being associated with a time domain at a predetermined range of frequencies;

a transforming component for providing a second plurality of digital signals, the second plurality of digital signals being associated with a frequency domain; and

a detecting component for determining wireless channel availability;

wherein;

the detecting component is configured to determine a plurality of signal strength levels associated with the second plurality of digital signals at a plurality of frequencies;

the detecting component is further configured to compare the plurality of signal strength levels to reference levels at the plurality of frequencies and to determine a band availability for wireless communication at the predetermined range of frequencies based on the comparing.

20. The system of claim 19 further comprising a demodulating the second plurality of digital signals.

21. The system of claim 19 further comprising a low-pass filter for filtering the analog signals.

22. The system of claim 19 further comprising a modifier component for shifting analog signals.

23. The system of claim 19 further comprising a low-noise amplifier for processing the analog signals.

24. The system of claim 19 further comprising a controller for selecting a frequency band for WRAN communication.

25. A method for determining availability of wireless communication links, the method comprising:

receiving wirelessly analog signals within a predetermined range of frequencies, the analog signals being associated with a time-domain;

modifying the analog signals to digital signals, the digital signals being characterized in a frequency domain, the digital signals including a first pilot signal and a second pilot signal;

determining a ratio of signal strength between the first pilot signal and the second pilot signal;

comparing the ratio to a predetermined threshold; and

determining a band availability for wireless communication at the predetermined range of frequencies based on the comparing.

26. The method of claim 25 wherein the first pilot signals comprises an audio pilot signal.

27. The method of claim 25 wherein the first pilot signals comprises a video pilot signal.

28. The method of claim 25 wherein the predetermined threshold is associated with the predetermined range of frequencies.

29. A method for determining availability of wireless communication links, the method comprising:

receiving wirelessly analog signals within a predetermined range of frequencies, the analog signals being associated with a time-domain;

converting the analog signals to digital signals, the digital signals being characterized in a frequency domain, the digital signals including a first pilot signal and a second pilot signal;

determining a ratio of signal strength between the first pilot signal and the second pilot signal;

comparing the ratio to a predetermined threshold;

determining a plurality of signal strength levels associated with the digital signals at a plurality of frequencies;

determining a first band availability metric for wireless communication at the predetermined range of frequencies based on the comparing the ratio;

comparing the plurality of signal strength levels to reference levels at the plurality of frequencies;

determining a second band availability metric for wireless communication at the predetermined range of frequencies based on the comparing the plurality of signal strength levels; and

determining a third band availability metric based on the first and second band availability metrics.

30. The method of claim 29 wherein the first pilot signals is associated with an NTSC broadcast characteristic.

31. The method of claim 29 further comprising assigning a weight to the first band availability metric.