A combination of cooperative and non-cooperative sensing methods improves spectrum utilization by switching network nodes not interfering with both primary system and cooperative secondary users to non-cooperative mode. The method then keeps record of the number of times the result of spectrum sensing of a network node matches or differs from the result of cooperative sensing. Also, the method sets thresholds to shift register values to determine when to switch back and forth between cooperative and non cooperative sensing modes, and sending control messages to let a non cooperative user access the spectrum. In the present disclosure two antenna are considered for each network node to separate the two types of control messages or broadcast and reply messages.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A spectrum sensing method in a communication system comprising: sensing a shared spectrum with a cognitive radio that is one of a plurality of cognitive radios; switching the cognitive radio, non interfering cognitive radios of the plurality of cognitive radios and cooperative secondary users to a non-cooperative mode; keeping a record of a number of times a result of spectrum sensing of the cognitive radio of the plurality of cognitive radios matches a result of cooperative sensing; setting a threshold in a shift register value to determine when to switch between cooperative and non-cooperative sensing modes based on comparing the shift register value to the threshold; and sending a control message to provide the non-cooperative cognitive radios of the plurality of cognitive radios access to the spectrum.
2. The method of claim 1 wherein the spectrum is a wireless radio frequency spectrum.
3. The method of claim 1 , wherein the switching is performed, regardless of a cooperative sensing result.
4. The method of claim 1 , wherein the keeping includes keeping a record in a shift register.
5. The method of claim 1 , wherein the plurality of cognitive radios include cooperative and non-cooperative cognitive radios in a same network.
6. The method of claim 1 further comprising avoiding interference from a non-cooperative cognitive radio to a primary system and cooperative cognitive radios by sending a broadcast message.
7. The method of claim 1 further comprising: avoiding interference from a non-cooperative cognitive radio to a primary system and cooperative cognitive radios by sending a broadcast message from the non-cooperative cognitive radio to neighboring cognitive radios whenever the non-cooperative cognitive radio senses that the spectrum is available.
8. The method of claim 7 further comprising: sending reply messages from neighboring cognitive radios to the non-cooperative cognitive radio in response to the broadcast message.
9. The method of claim 7 further comprising: sending reply messages from neighboring cognitive radios to the non-cooperative cognitive radio in response to the broadcast message, wherein respective reply messages contain information on whether transmission from the non-cooperative cognitive radio causes harmful interference.
10. The method of claim 1 further comprising: avoiding interference to a primary user or cooperative cognitive radios by using two antennas for each cognitive radio, wherein one antenna is for transmission over a certain channel and the other antenna is for sending a control message.
11. The method of claim 10 , wherein control messages comprise broadcast messages and reply messages.
12. A spectrum sensing apparatus in a communication system comprising: a cognitive radio that includes a sensor to sense a shared spectrum, the cognitive radio being one of a plurality of cognitive radios in the communication system; a switch configured to change an operational mode to a non-cooperative mode of the cognitive radio and a portion of the plurality of cognitive radios that are not interfering with a primary system and cooperative cognitive radios; a shift register disposed in the cognitive radio to keep record of a number of times a result of spectrum sensing of the cognitive radio matches a result of cooperative sensing; comparator circuity configures to compare the shift register value to a threshold to determine if the switch should change the mode between cooperative and a non-cooperative sensing; and a plurality of transmitter antennas configured to send a control message to provide a non-cooperative cognitive radio access to the shared spectrum.
13. The apparatus of claim 12 , wherein the plurality of tramitter antennas include two antennas that respectively send broadcast messages and reply messages.
14. The apparatus of claim 12 , wherein the spectrum is a wireless radio frequency spectrum.
15. A non-transitory computer-readable storage medium including computer executable instructions, wherein the instructions, when executed by a computer, cause the computer to perform a method of sensing, the method comprising: sensing a shared spectrum with a cognitive radio that is one of a plurality of cognitive radios; switching the cognitive radio,non interfering cognitive radios of the plurality of cognitive radios, and cooperative secondary users to a non-cooperative mode; keeping a record of a number of times a result of spectrum sensing of the cognitive radio of the plurality of cognitive radios matches a result of cooperative sensing; setting a threshold in a shift register value to determine when to switch between cooperative and non-cooperative sensing modes based on comparing the shift register value to the threshold; and sending a control message to provide the non-cooperative cognitive radios of the plurality of cognitive radios access to the shared spectrum.
16. The method of claim 15 , wherein the switching is performed, regardless of a cooperative sensing result.
17. The method of claim 15 , wherein the keeping includes keeping a record in a shift register.
18. The methods of claim 15 further comprising: avoiding interference to a primary user or cooperative cognitive radios by using two antennas for each cognitive radio, wherein one antenna is for transmission over a predetermined channel and the other antenna is for sending control messages, wherein the control messages include broadcast messages and reply messages.
19. The method of claim 15 further comprising: avoiding interference from a non-cooperative cognitive radio to a primary system and cooperative cognitive radios by sending a broadcast message from the non-cooperative cognitive radio to neighboring cognitive radios whenever the non-cooperative cognitive radio senses that the spectrum is available.
20. The method of claim 15 further comprising: sending reply messages from neighboring cognitive radios to the non-cooperative cognitive radio in response to the broadcast message, wherein respective reply messages contain information on whether transmission from a non-cooperative cognitive radio causes harmful interference.
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December 6, 2013
February 23, 2016
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