Robust cooperative spectrum sensing for cognitive radios

• US 7,965,641 B2
• Filed: 02/14/2008
• Issued: 06/21/2011
• Est. Priority Date: 02/14/2008
• Status: Active Grant

• Current Assignee: Lingna Holdings Pte LLC (Intellectual Ventures LLC)
• Original Assignee: Lingna Holdings Pte LLC (Intellectual Ventures LLC)
• Inventors: Zhang, Wei, Ben Letaief, Khaled
• Primary Examiner(s): Ngo; Ricky
• Assistant Examiner(s): Gidado; Rasheed
• Application Number:
  US12/031,521
• Publication Number:
  US 20090207735A1
• Time in Patent Office: 1,223 Days
• Field of Search: 370/237
• US Class Current: 370/237
• CPC Class Codes: H04B 7/026 Co-operative diversity, e.g. using fixed or mobile stations as relays
• CPC Class Codes: H04B 7/15592 Adapting at the relay station communication parameters for supporting cooperative relaying, i.e. transmission of the same data via direct - and relayed path cooperative diversity H04B7/024
• CPC Class Codes: H04L 1/0077 Cooperative coding
• CPC Class Codes: H04L 1/0606 Space-frequency coding
• CPC Class Codes: H04L 1/0618 Space-time coding
• CPC Class Codes: H04L 27/0006 Assessment of spectral gaps suitable for allocating digitally modulated signals, e.g. for carrier allocation in cognitive radio for spectrum sharing between different networks H04W16/14
• CPC Class Codes: H04L 5/0032 Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation
• CPC Class Codes: H04L 5/0062 Avoidance of ingress interference, e.g. ham radio channels
• CPC Class Codes: H04L 5/0091 Signaling for the administration of the divided path
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks

Abstract

The disclosed subject matter relates to communicatively coupled cognitive radio systems, devices, methodologies, or combinations thereof, facilitating improved utilization of unused portions of spectral bands by secondary users generally allocated to other primary users. This improved utilization can be achieved by cooperative spectrum sensing employing ST coding and/or SF coding for transmit diversity. Further, cooperative spectrum sensing can be improved by employing relay diversity with or without algebraic coding. It is illustrated that a threshold probability of false alarm can be reduced by applying transmit diversity with space time coding and/or space frequency coding. It is further illustrated that relay diversity can be employed to compensate for reduced sensing diversity order were some nodes in a cooperative spectrum sensing system cannot report directly. It is disclosed that algebraic coding can be combined with relay diversity to decrease the threshold probability of false alarm in relay diversity systems while maintaining high levels of sensing diversity order.

Claims

1. A system, comprising:

a first device, comprising;

a first sensing component configured to generate first sensed information related to occupation of a spectral band; and

a first reporting component which is communicatively coupled to the first sensing component and configured to report the first sensed information; and

a second device, comprising;

a second sensing component configured to generate second sensed information related to occupation of the spectral band;

a second reporting component which is communicatively coupled to the second sensing component and configured to encode the first sensed information and the second sensed information, yielding encoded information, based on a rotational matrix for use, at least in part, in algebraic coding, and to report the encoded information representing the first sensed information and the second sensed information; and

a determination component configured to determine whether the spectral band can be occupied, based at least in part on decoding and analyzing the encoded information reported by the second reporting component.

2. The system of claim 1, wherein at least one of the first sensing component or the second sensing component comprises an energy detector configured to sense energy over a frequency band and time window.

3. The system of claim 1, wherein at least one of the first sensing component and the second sensing component further comprises a decision component, wherein the decision component is configured to locally decide and reduce a state of spectral band occupancy to a quantized symbolic representation of spectral band occupancy.

4. The system of claim 3, wherein the decision component is further configured to decide and reduce the state of the spectral band occupancy to a quantized symbolic representation of spectral band occupancy, which is embodied in a binary representation system representing at least an occupied state and a not occupied state of the spectral band.

5. The system of claim 1, wherein the second reporting component is further configured to encode the first sensed information and the second sensed information in space-time coding, space-frequency coding, or a combination thereof, at least in part, to increase a transmit diversity.

6. The system of claim 5, wherein the second reporting component is further configured to determine what portion of the first sensed information and the second sensed information to encode based, at least in part, on a predetermined reporting confidence level between at least the first sensing component and the second sensing component.

7. The system of claim 1, wherein the determination component further comprises a fusion component that is configured to fuse the encoded information with other information received from a plurality of reporting components, yielding fused information, to facilitate determinations relating to whether the spectral band can be occupied.

8. The system of claim 7, wherein the determination component further comprises an analysis component configured to determine whether the spectral band can be occupied based, at least in part, on the encoded information, the fused information, inferences formed about occupation of the spectral band, or combinations thereof.

9. The system of claim 1, further comprising:

a plurality of devices, each device comprising at least one sensing component and at least one related communicatively coupled reporting component; and

at least a portion of a network of cooperative spectrum sensing devices, wherein at least a subset of the plurality of devices are configured to report information related to the occupation of a spectral band to the determination component by way of space-time coded transmit diversity, space-frequency coded transmit diversity, relay diversity, or algebraically coded relay diversity.

10. The system of claim 9, wherein at least one device of the plurality of devices is a cognitive radio device comprising at least one sensing component and at least one related communicatively coupled reporting component.

11. The system of claim 9, wherein the determination component comprises at least a portion of a cognitive radio device.

12. The system of claim 9, wherein at least one of the plurality of devices comprises a mobile device.

13. A non-transitory computer-readable storage medium containing computer-executable instructions that, in response to execution by a computing device, cause the computing device to perform acts comprising:

receiving, at a second location, second information related to occupancy of a spectral band at one or more locations;

receiving, by at least the second location, relayed third information related to at least a portion of first information related to occupancy of the spectral band at the one or more locations received at a first location;

employing a rotational matrix to algebraically encode fourth information relating to the third information relayed from the first location to the second location and fifth information relating to at least a portion of the second information; and

reporting, from the second location the fourth information and the fifth information to facilitate determining whether the spectral band is available to be occupied based at least in part on the fourth information and the fifth information.

14. The non-transitory computer-readable storage medium of claim 13, the instructions, in response to execution by a computing device, cause the computing device to perform acts further comprising:

encoding at least a subset of the fourth information and the fifth information at a corresponding subset of the one or more locations based in part on a predetermined threshold, generating encoded information;

reporting the encoded information; and

wherein the determining whether the spectral band is available to occupy includes determining based at least in part on the encoded information.

15. The non-transitory computer-readable storage medium of claim 14, wherein the encoding at least a subset of the fourth information and the fifth information is by space-time coding, space-frequency coding, or combinations thereof.

16. The non-transitory computer-readable storage medium of claim 15, wherein the encoding of the at least the subset of the fourth information and the fifth information includes encoding based at least in part on a predetermined threshold.

17. The non-transitory computer-readable storage medium of claim 16, wherein the encoding based on the predetermined threshold includes encoding based at least in part on an inference relating to a confidence level that the encoded information will be correctly reported.

18. A device for use in a spectrum sensing system, comprising:

a processor;

a memory communicatively coupled to the processor, and containing instructions comprising;

a receiving component configured to receive received information related to the occupancy of a spectral band from a plurality of other devices;

a sensing component configured to generate sensed information related to the occupation of the spectral band, as sensed at a location of the device;

a fusing component configured to fuse the sensed information and the received information to form fused information;

a transformation component configured to transform the fused information using a rotational matrix, for use, at least in part, in algebraic coding to generate transformed information;

a determination component configured to generate, based at least in part on the transformed information, a determination of whether to occupy the spectral band; and

a reporting component configured to report the determination of whether to occupy the spectral band.

19. The device of claim 18, wherein the reporting component is further configured to report the transformed information.

20. A system, comprising:

means for sensing information related to the occupation of a spectral band at a location of a device yielding sensed information;

means for receiving received information related to the occupancy of the spectral band from at least one other device;

means for fusing the sensed information and the received information to form fused information;

means for transforming the fused information using a rotational matrix, for use, at least in part, in algebraic coding to generate transformed information; and

means for determining, based at least in part on the transformed information, whether to occupy the spectral band.

21. The system of claim 20, further comprising:

means for detecting energy over a frequency band and time window.

22. The system of claim 20, further comprising:

means for reporting whether to occupy the spectral band.

23. The system of claim 22, wherein the means for determining includes means for determining a confidence level associated with whether to occupy the spectral band, and wherein the means for reporting reports the confidence level.