FCSS: CSMA/CA based Fast Cooperative Spectrum Sensing over multiband cognitive networks

The design of a cooperative spectrum sensing strategy has to take two aspects into consideration: from the physical layer perspective, a number of secondary users cooperatively measuring the channels to improve the detection performance, and from the MAC layer perspective, the users efficiently reporting their measurement results to a decision entity. Both operations are time critical and required for efficient spectrum opportunity exploitation by the secondary system. However, most of the existing cooperative solutions in the literature ignore the reporting process or over simplify it by assuming a perfect timeslotted multiple access. In this paper, we consider a CSMA/CA based reporting process. We show that fairness no longer plays a role in multiple access of the reporting process. Instead, fastness becomes the dominant measure of the MAC protocol. We propose a Fast Cooperative Spectrum Sensing (FCSS) scheme over multiband cognitive networks by exploiting concurrent occurrence of the spectrum sensing activities and the reporting process with an improved CSMA/CA based MAC protocol. The proposed scheme incorporates a joint static and random sensor assignment algorithm over multiple channels. A mathematical model has been developed for evaluating the performance of FCSS and serving as a basis to select appropriate parameters.