A Spectrum Sensing Scheme for Cognitive Radios

Cognitive radio (CR) is viewed as a possible solution to the problem of radio spectrum congestion. CR is the promising radio technology which aims to detect and utilize the temporally unused spectrum bands by sensing its radio environment in order to improve spectrum utilization. To enhance the sensing performance, cooperative spectrum sensing has been proposed. However, when the number of cognitive user tends to be very large, the bandwidth for reporting sensing results to the common receiver will be very huge. In the paper, we therefore introduce a new credibility factor sensing (CFS) algorithm with quantization to decrease the average number of sensing bits to the common receiver. According to the energy detection, if the energy is located in the "decision" region, then the cognitive user sends 1 bit or 2 bits quantization for reporting its sensing result based on credibility factor and likelihood decision. Otherwise, the cognitive user sends nothing. Performance evaluations clearly reveal that the average number of sensing bits decreases greatly without noticeable loss in sensing performance.