METHOD FOR ADDRESSING USER LOCATION ERRORS IN A COGNITIVE RADIO SYSTEM

• US 20090061779A1
• Filed: 08/28/2007
• Published: 03/05/2009
• Est. Priority Date: 08/28/2007
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Weisman, Douglas H., Chiou, Wayne W., Gurney, David P., Ekl, Randy L.
• Granted Patent: US 8,213,954 B2
• Time in Patent Office: Days
• US Class Current: 455/63.100
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition

Abstract

A cognitive radio (CR) system (102) includes CR units (108, 110) that determine and update location-based system operating parameters to avoid interference with other systems operating in the same frequency band. Operational Location Uncertainty region and Allowed Location Error regions can be applied. The CR unit trades off between both, available channels and maximum system operating parameters, such that as Location Uncertainty of the CR device increases, available CR channels and location-based CR system operating parameters decrease over a maximum network reach.

Claims

1. A method of operating a cognitive radio (CR) unit, comprising:

estimating an operating location of the CR unit;

determining an operating location estimate accuracy;

determining an Allowed Location Error Region using the estimated operating location of the CR unit and the determined location estimate accuracy;

determining at least one location-based system operating parameter by performing a optimum operating parameter search over the Allowed Location Error Region; and

operating the CR unit with the determined location-based system operating parameter.

2. The method of claim 1, further comprising repeating the steps of estimating through operating in response to the CR unit changing operating location.

3. The method of claim 1, further comprising:

providing an allowed location determination error for the CR unit by a regulatory authority;

wherein the Allowed Location Error Region is centered on the operating location of the CR unit, and extends outward to a distance equal to the difference between the allowed location determination error and the operating location estimate accuracy.

4. The method of claim 1, wherein the determined location based system operating parameter comprises at least one of:

an allowed transmit power, an allowed operating bandwidth, an allowed transmit time duration.

5. The method of claim 1, wherein the optimum parameter search comprises a search for a maximum value over the Allowed Location Error Region.

6. The method of claim 1, wherein the location-based system operating parameter is determined by accessing a stored geo-location database.

7. The method of claim 6, wherein the geo-location database is stored with variable spatial resolution.

8. The method of claim 7, wherein the spatial resolution of the geo-location database decreases as distance from a central CR unit operating location increases.

9. A method of optimizing operating parameters for a cognitive radio (CR) unit operating within a geographic area, comprising:

deriving a current location and location accuracy estimate of a CR unit within the network;

determining an operating Location Uncertainty Region for the CR unit;

determining an Allowed Location Error Region for the CR unit;

determining at least one location-based system operating parameter by performing a minimum operating parameter search over the Location Uncertainty Region for the CR unit;

determining an updated location-based system operating parameter by performing a maximum operating parameter search over an Allowed Location Error Region centered on the minimum operating parameter location; and

operating the CR unit using the updated location-based system operating parameter.

10. The method of claim 9, wherein the step of performing a minimum operating parameter search comprises:

searching all location data points contained with the Location Uncertainty Region; and

selecting the location with the minimum CR system operating parameter.

11. The method of claim 9, wherein the location-based system operating parameter comprises at least one of:

an allowed transmit power, an allowed operational bandwidth, and an allowed transmit time duration.

12. The method of claim 9, wherein the operating Location Uncertainty Region is determined by one of:

estimating a maximum network reach, determining an actual network reach, CR unit mobility and a predetermined operating region.

13. The method of claim 12, wherein the maximum network reach is estimated from at least one of:

an allowed transmit power level, antenna pattern data, a directional gain.

14. The method of claim 9, further comprising:

changing location of the CR base station; and

repeating the steps of deriving a current location through operating.

15. The method of claim 9, wherein the location-based system operating parameter is determined by accessing a stored geo-location database having variable spatial resolution that decreases as distance from a central CR unit operating location increases.

16. The method of claim 9, further comprising adjusting the operating Location Uncertainty Region based on mobility of the CR unit over an area in which the CR unit is contained and traversing over a period of time.

17. A cognitive radio (CR) communication network, comprising:

a CR base station located within a network Location Uncertainty Region, the CR base station having an estimated maximum network reach;

a prospective subscriber CR device, the prospective subscriber CR device having an Allowed Location Error Region about its center; and

the prospective subscriber CR device increasing its Location Uncertainty in exchange for a decrease in available channels from the CR base station and a decrease in transmit power from the CR base station.

18. The cognitive radio of claim 17, further comprising a geo-location database stored within the base station and having stored CR system operating parameters including the transmit power.

19. A method of updating a cognitive radio (CR) location-based operating parameters for communicating within a CR communication network comprising:

determining an Allowed Location Error Region for the CR unit;

determining an operational Location Uncertainty Region of the CR unit;

performing a minimum operating parameter search over the operational Location Uncertainty Region to determine a minimum operating parameter location;

performing a maximum operating parameter search over the Allowed Location Error Region centered on the minimum operating parameter location; and

updating the location-based system operating parameters with the maximum system operating parameter.

20. The method of claim 19, further comprising accessing geo-location information stored within the CR unit providing system operating parameters versus location.

21. The method of claim 19, wherein the location based system operating parameters comprise at least one of:

a maximum allowable transmit power, an allowable operational bandwidth, an allowable transmit time duration.

22. The method of claim 19 wherein the operational Location Uncertainty Region is determined based on one or more of:

a maximum network reach, a predetermined operating region, CR device mobility.

23. The method of claim 19, wherein the Allowed Location Error Region is determined by a current location of the CR unit, location estimate accuracy of the CR unit and an allowed location determination error for the CR unit.

24. A cognitive radio (CR) device, comprising:

a transmitter;

a controller coupled to the transmitter, the controller and transmitter maintaining system operating parameters for the CR device; and

the CR device trading off between both available channels and maximum system operating parameters, such that as Location Uncertainty of the CR device increases, available CR channels and CR system operating parameters decrease.

25. The CR device of claim 24, wherein the controller further comprises geo-location information for determining CR system operating parameters versus location.

26. The CR device of claim 24, wherein the CR device comprises a mobile CR radio operating within a public safety network.

27. A method of communicating in a cognitive radio (CR) communication network having a mobile CR unit, comprising:

estimating the location of the mobile unit;

applying at least one of;

a Location Uncertainty Region and Location Error to the unit'"'"'s estimated location; and

optimizing operating parameters by altering the at least one of Location Uncertainty Region and Location error.

28. The method of claim 27, wherein the CR system operating parameters comprises a global CR transmit power limit utilized by any CR units within the Location Uncertainty Region.

29. The method of claim 27, wherein the communication network comprises an in-home TVWS communication system, and wherein the location of the CR unit is derived from a home address linked to a cable set top box located in the home.

30. The method of claim 27, wherein the input includes one or more of street address, locale and city.

31. The method of claim 27, wherein the step of applying at least one of a Location Uncertainty Region and Location Error to the unit'"'"'s estimated location, comprises:

a maximization technique for trading off Location Error for maximum allowed system operating parameters; and

a minimization technique for trading off a Location Uncertainty Region for minimum allowed system operating parameters.

32. The method of claim 27, wherein the Location Uncertainty Region is determined by estimating maximum network reach.

33. The method of claim 32, wherein maximum network reach is based on propagation models and the current value of allowed transmit power.

34. The method of claim 31 wherein the system operating parameters comprise one or more of:

CR base unit antenna pattern, directional gain applied to refine the network reach estimate.

35. The CR device of claim 27, wherein the CR unit comprises a mobile CR unit operating within a Public Safety Network.

36. The method of claim 27, wherein the application of a Location Uncertainty Region further comprises:

examining the Location Uncertainty Region for co-channel transmitters within the region; and

eliminating any channel having co-channel transmitters within the bounds of the Location Uncertainty Region from subsequent searches.