Agility improvements by censor-based cooperative spectrum sensing in cognitive radio networks

In cognitive radio networks, cooperative spectrum sensing is used to improve the performance of spectrum sensing. However, the limit of control channel bandwidth and the delay of sensing will more impact the spectrum sensing performance when the number of cognitive user becomes very large. In order to solve this problem, censor-based cooperative spectrum sensing scheme is presented to reduce communication overhead and total sensing time thus improve the agility of the cognitive radio networks, which indicates that the local sensing observation is censored and only local decision with reliable information is allowed to transmit to cognitive base-station. In order to prefix appropriate thresholds, a tradeoff between communication overhead and spectrum utilization is characterized to obtain the optimal no decision probability. Numerical results show that agility gain can be available without the loss of spectrum sensing reliability. Moreover, an improved censor-based scheme is proposed to reduce the spectrum utilization loss.