POWER CONTROL IN COGNITIVE RADIO SYSTEMS BASED ON SPECTRUM SENSING SIDE INFORMATION

• US 20080268892A1
• Filed: 04/09/2008
• Published: 10/30/2008
• Est. Priority Date: 04/26/2007
• Status: Active Grant

• Current Assignee: Lingna Holdings Pte LLC (Intellectual Ventures LLC)
• Original Assignee: Hong Kong University of Science and Technology
• Inventors: Zhang, Wei, Hamdi, Karama, Letaief, Khaled Ben
• Granted Patent: US 8,041,380 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 52/242 taking into account path loss
• CPC Class Codes: H04W 52/243 taking into account interferences
• CPC Class Codes: H04W 52/246 where the output power of a terminal is based on a path parameter calculated in said terminal
• CPC Class Codes: H04W 52/26 using transmission rate or quality of service QoS [Quality of Service]
• CPC Class Codes: H04W 52/265 taking into account the quality of service QoS
• CPC Class Codes: H04W 52/283 Power depending on the position of the mobile
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

For cognitive radio systems, the transmit power of a cognitive radio device is controlled so that the cognitive, unlicensed radio device does not interfere with the use of a shared spectrum by a primary, licensed device. Controlling the transmit power includes determining a distance, or a function of the distance, between a primary transmitter of the primary device and the cognitive radio device based on sensing information from a spectrum sensing process. The maximum transmit power of the cognitive radio device is then dynamically controlled based on the distance, or the function of the distance, while considering a worst case scenario of an underlying cognitive radio model, to guarantee a quality of service requirement of the primary device.

Claims

1. A method for controlling transmit power of a cognitive radio device sharing spectrum with a primary device without interfering with the primary device'"'"'s use of the spectrum, comprising:

determining a parameter relating to a distance between a primary transmitter of the primary device and the cognitive radio device based on sensing information from a spectrum sensing process that senses the presence of the primary device on the spectrum based on signals emitted from the primary transmitter; and

dynamically controlling a transmit power of the cognitive radio device based on the parameter to fulfill a QoS requirement of the primary device.

2. The method according to claim 1, wherein the determining includes determining the distance between the primary transmitter and the cognitive radio device based on the sensing information.

3. The method according to claim 1, wherein the determining includes determining a path loss between the primary transmitter and the cognitive radio device based on the sensing information.

4. The method according to claim 1, wherein the determining includes calculating the average probability of missing energy detection with respect to detecting the primary transmitter of the primary device during spectrum sensing performed by the cognitive radio device.

5. The method according to claim 4, wherein the determining includes determining the distance based on the average probability of missing energy detection.

6. The method according to claim 4, wherein the determining includes determining the parameter as a function of the distance based on the average probability of missing energy detection.

7. The method according to claim 6, wherein the determining includes determining the parameter as a path loss function as a function of the distance based on the average probability of missing energy detection.

8. A computer readable medium comprising computer executable instructions for performing the method of claim 1.

9. A cognitive radio device employing spectrum sensing for sensing the presence of a primary device on a designated portion of a network spectrum based on signals emitted from a primary transmitter of the primary device, comprising:

a spectrum sensing component for sensing presence information about utilization of the designated portion of the network spectrum by the primary device, whereby the cognitive radio device shares the designated portion of the network spectrum with the primary device; and

a power control component for controlling a transmission power of the cognitive radio device based on at least one output from the spectrum sensing component such that the use of the designated portion of the network spectrum by the cognitive radio device does not interfere with use by the primary device, wherein the power control component controls the transmit power based on a worst case location associated with the primary device in order to guarantee a QoS requirement of the primary device.

10. The cognitive radio device according to claim 9, wherein the power control component determines a distance between a primary transmitter of the primary device and the cognitive radio device based on the presence information.

11. The cognitive radio device according to claim 9, wherein the power control component determines a path loss characteristic between a primary transmitter of the primary device and the cognitive radio device based on the presence information.

12. The cognitive radio device according to claim 9, wherein the at least one output from the spectrum sensing component includes an output of an average probability of missing energy detection with respect to determining the presence of a primary transmitter of the primary device by the spectrum sensing component.

13. The cognitive radio device according to claim 12, wherein the power control component controls the transmission power of the cognitive radio device based on a function of the average probability of missing energy detection.

14. The cognitive radio device according to claim 12, wherein the power control component controls the transmission power of the cognitive radio device based on a distance between the primary device and the cognitive radio device calculated based on the average probability of missing energy detection.

15. The cognitive radio device according to claim 12, wherein the power control component controls the transmission power of the cognitive radio device based on a path loss function, mathematically related to a distance between the primary device and the cognitive radio device, calculated based on the average probability of missing energy detection.

16. A method for controlling power of a cognitive radio device in a cognitive radio system to prevent interference with licensed devices, comprising:

deriving at least one set of candidate distances corresponding to at least one licensed device from the cognitive radio device based on spectrum sensing side information including, for each licensed device of the at least one licensed device, determining a shortest distance of the set of candidate distances to the corresponding licensed device; and

dynamically controlling transmit power of the cognitive radio based on the one or more shortest distances to the at least one licensed device thereby substantially preventing interference by the cognitive radio device with the at least one licensed device.

17. The method of claim 16, wherein the deriving includes deriving, for each licensed device of the at least one licensed device, a range of possible distances to the licensed device from the cognitive radio device from spectrum sensing side information received from the licensed device and the determining includes selecting the closest distance of the range.

18. The method according to claim 16, wherein the deriving includes deriving at least one path loss characteristic of the at least one channel between the at least licensed device and the cognitive radio device based on the spectrum sensing side information.

19. The method according to claim 16, wherein the deriving includes calculating, for each licensed device of the at least one licensed device, the average probability of missing energy detection with respect to detecting transmissions of the licensed device during spectrum sensing performed by the cognitive radio device.

20. A system for performing power control for a cognitive radio device in a cognitive radio system, comprising:

means for determining a minimum distance, or a function related to the minimum distance, between a primary transmitter of a primary device and a cognitive radio device based on information from a spectrum sensing process for sensing the presence of the primary device on a shared spectrum based on signals emitted from the primary transmitter; and

means for dynamically controlling a maximum transmit power of the cognitive radio device based on the minimum distance, or the function related to the minimum distance, output from the means for determining to guarantee a quality of service requirement of the primary device while the cognitive radio device shares the shared spectrum with the primary device.