The impact of reporting MAC on cooperative spectrum sensing in multiband cognitive networks

Cooperative spectrum sensing generally consists of two consecutive stages: sensing and reporting, where sensors measure channels at the sensing stage and then use a multiple access protocol to report their local measurement results which we call the reporting MAC protocol. In this paper, we examine the impact of reporting MAC protocols on centralized cooperative sensing in multiband cognitive networks. Specifically, we study the applicability of TDMA and IEEE 802.11 CSMA/CA protocols for cooperative spectrum sensing reporting. A general mathematical model has been developed to quantify the achievable bandwidth utilization within a secondary system, which takes into account different combinations of sensor assignment strategies, reporting MAC, fusion rules, and regulatory constraints. The model allows the cross-layer optimization on the PHY and MAC layers of cooperative detection. The results show that the reporting control signaling can dominate the sensing overhead and result in significant capacity loss in some scenarios, which emphasizes the importance of using an efficient reporting MAC in cooperative sensing.