Optimal Cooperative Sensing Assignment and Radio Resource Allocations for Cognitive Radio Systems

摘要

This study investigates the joint sensing assignment and resource allocations for Cognitive Radio (CR) systems where multiple Secondary Users (SUs) opportunistically share the channels of Primary System (PS) through cooperative sensing. The key questions concerned here are how to assign different SUs to sense different channels and how to allocate the transmission power and bandwidth for SUs such that the detected idle channels of PS are fully utilized. Specifically, the cooperative spectrum sensing improves the detection accuracy and reduces the potential interference to PS due to mis-detection. However, the cooperative spectrum sensing and the consequent reports of sensing results consume additional energy which should be taken account of in the SU resource allocations. Hence, the coupling effect between the spectrum sensing and the consequent resource allocations is critical for CR to optimize its performance. Based on these considerations, the problem of joint sensing assignment and resource allocations for CR is formulated as a mixed binary nonlinear programming problem and a two-layer procedure is proposed to obtain the optimal solutions. The extensive results show that due to the energy overhead for sensing and reporting, the optimal number of SUs assigned to sense the PU channel does not increase in the idle probability of the channel monotonically. Meanwhile, to maximize the SUs throughput, the consequent optimal transmission power and bandwidth allocations heavily depend on the sensing accuracy determined by the optimal sensing assignment.