METHOD AND APPARATUS FOR CONTROLLING TRANSMIT POWER AND INCUMBENT PROTECTION IN A COGNITIVE RADIO SYSTEM

• US 20090197627A1
• Filed: 02/01/2008
• Published: 08/06/2009
• Est. Priority Date: 02/01/2008
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Gurney, David P., Kuffner, Stephen L., Ecklund, Lawrence M.
• Granted Patent: US 8,068,826 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 52/243 taking into account interferences
• CPC Class Codes: H04W 52/30 using constraints in the total amount of available transmission power

Abstract

A cognitive radio (CR) device (208 and/or 218) avoids interference with an incumbent (207) receiver by determining maximum allowed transmit power levels of the CR device based on estimates of the incumbent signal level and transmit splatter levels of the CR device. The CR device (208 and/or 218) avoids interference with the incumbent receiver while transmitting with maximum transmit power levels.

Claims

1. A method of operating a cognitive radio (CR) device to avoid interference with an incumbent receiver, comprising:

determining maximum allowed transmit power level of the CR device based on at least one estimated incumbent signal level in a local environment, at least one corresponding estimated transmitter splatter level of the CR device, and at least one co-channel incumbent receiver protection requirement; and

transmitting with no more than the maximum allowed transmit power level thereby avoiding interference with the incumbent receiver.

2. The method of claim 1 wherein the CR device comprises a geo-location enabled CR device.

3. The method of claim 2, wherein the at least one estimated incumbent signal level is computed based on CR device location and respective incumbent transmitter locations.

4. The method of claim 1, wherein the step of determining further comprises applying an offset from the at least one estimated incumbent signal level, said offset determined by the at least one co-channel incumbent receiver interference protection requirement;

and

selecting a transmit power level that is a minimum of the at least one estimated incumbent signal level.

5. The method of claim 4 wherein the step of determining further comprises:

applying an offset from the at least one estimated incumbent signal level based on the least one corresponding estimated transmitter splatter level and the at least one incumbent receiver co-channel interference protection requirement; and

selecting a transmit power level that is a minimum as determined by the at least one transmitter splatter level.

6. The method of claim 1, where the CR device comprises a sensing-only CR device.

7. The method of claim 1, where the at least one estimated incumbent signal level is measured using spectral sensing.

8. A method of operating a cognitive radio (CR) device to avoid interference with an incumbent receiver, comprising:

estimating an incumbent signal level at the incumbent receiver;

determining interference protection ratios for the incumbent device, including a co-channel interference protection ratio for the incumbent;

applying a transmit power level reduction to the CR device based on the interference protection ratios and the estimated incumbent signal level;

estimating at least one CR transmitter out-of-band splatter level; and

applying a further CR transmit power level reduction based on the estimated CR transmitter splatter level, estimated incumbent signal level, and the incumbent receiver co-channel interference protection ratio.

9. The method of claim 8, wherein the steps are repeated for a plurality of incumbent signals received at the incumbent receiver.

10. The method of claim 8, wherein the step of estimating an incumbent signal level comprises computing the incumbent signal level for a channel based on geo-location of the incumbent receiver.

11. The method of claim 8, wherein the step of estimating an incumbent signal level comprises taking spectral sensing measurements of the incumbent signal.

12. The method of claim 8, wherein the step of estimating the at least one CR transmitter out-of-band splatter level is predicted based on a predetermined mask level.

13. The method of claim 8, wherein the step of estimating the at least one CR transmitter out-of-band splatter level is based on a combination of predetermined CR transmitter characteristics and knowledge of CR transmitter power level.

14. The method of claim 8, wherein the step of estimating the at least one CR transmitter out-of-band splatter level is based on:

measuring the at least one CR transmitter out-of-band emission at a least one power output level; and

utilizing the measured at least one CR transmitter out-of-band splatter level during the step of applying a further transmit power level reduction.

15. The method of claim 8, wherein the incumbent receiver is a digital television receiver.

16. The method of claim 8, wherein the at least one transmitter out-of-band splatter level is modeled based on knowledge of nonlinear performance of the transmitter and the transmit power level setting.

17. The CR device of claim 8, wherein the CR device comprises a mobile CR radio operating within a public safety network.

18. The CR device of claim 8, wherein the CR device periodically checks for location changes or sensed signal level changes and updates incumbent signal strength and CR transmit power level.

19. A cognitive radio (CR) device operating within an incumbent receiver'"'"'s spectrum, the CR device comprising:

a transmitter;

a controller coupled to the transmitter and having at least one of a geo-location database or sensing capability, the CR device estimating incumbent signal levels and estimating CR transmitter out-of-band splatter levels; and

the CR device adjusting transmit power level in response to the estimated incumbent signal levels and the estimated CR transmitter out-of-band splatter levels.

20. The CR device of claim 19, wherein the CR device comprises a mobile CR radio operating within a public safety network and the CR device includes at least one of sensing capability and geo-location capability, and the incumbent receiver comprises a television receiver.

21. A communications network, comprising:

a licensed TV receiver operating in a television white space (TVWS) environment;

a cognitive radio device operating in the TVWS environment, the CR device transmitting with a modulated signal having a passband level that does not exceed the TV receiver selectivity limits for adjacent channel, alternate channel and beyond alternate channel; and

the CR device emitting out-of-band emissions (OOBE) falling co-channel with the licensed incumbent signal that do not exceed a predetermined co-channel interference protection ratio.

22. The communication network of claim 21, wherein the CR device comprises a geo-location enabled CR device.

23. The communication network of claim 22, wherein the CR device periodically accesses an incumbent database.

24. The communication network of claim 23, wherein the CR device updates its transmit power level based on accessing the incumbent database.

25. The communication network of claim 21, wherein the CR device comprises a sensing-only CR device.

26. The communication network of claim 21 wherein the CR device estimates out-of-band emission (OOBE) levels in adjacent, alternate and beyond alternate channels.

27. The communication network of claim 26, wherein the estimated OOBE levels are based on a CR device transmit power level.