Method and apparatus for controlling transmit power and incumbent protection in a cognitive radio system

• US 8,068,826 B2
• Filed: 02/01/2008
• Issued: 11/29/2011
• Est. Priority Date: 02/01/2008
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola Solutions, Inc.
• Inventors: Kuffner, Stephen L., Gurney, David P., Ecklund, Lawrence M.
• Primary Examiner(s): GESESSE, TILAHUN
• Application Number:
  US12/024,311
• Publication Number:
  US 20090197627A1
• Time in Patent Office: 1,397 Days
• Field of Search: 455/426.1, 455/423, 455/41.1, 455/41.2, 455/426.2, 455/40, 455/522, 455/67.11
• US Class Current: 455/423
• 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;

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; and

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; and

transmitting with the maximum allowed transmit power level thereby avoiding interference with the incumbent receiver while maximizing transmit power level of the CR device.

2. 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 into a co-channel of the incumbent receiver;

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 thereby avoiding interference with the incumbent receiver.

3. The method of claim 2, wherein the steps are repeated for a plurality of incumbent signals received at the incumbent receiver.

4. The method of claim 2, 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.

5. The method of claim 2, wherein the step of estimating an incumbent signal level comprises taking spectral sensing measurements of the incumbent signal.

6. The method of claim 2, 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.

7. The CR device of claim 2, wherein the CR device comprises a mobile CR radio operating within a public safety network.

8. The CR device of claim 2, wherein the CR device periodically checks for location changes or sensed signal level changes and updates incumbent signal strength and CR transmit power level.

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

10. 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, 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;

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.

11. 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, 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; 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.

12. 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, wherein the at least one CR transmitter out-of-band splatter level is modeled based on knowledge of nonlinear performance of the transmitter and the transmit power level setting; 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.

13. 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 into a co-channel of the incumbent receiver'"'"'s spectrum; 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 thereby avoiding interference with the incumbent receiver.

14. The CR device of claim 13, wherein the CR device comprises a mobile CR radio operating within a public safety network and the mobile CR radio includes at least one of sensing capability and geo-location capability.