Cross-Layer Rethink on Sensing-Throughput Tradeoff for Multi-Channel Cognitive Radio Networks

The tradeoff between the interference to primary users' (PUs) and secondary users' (SUs) throughput is of great importance in cognitive radio networks. Both imperfect spectrum sensing and multi-channel access contention impact the tradeoff. In this paper, jointly considering imperfect spectrum sensing and multi-channel access contention from cross-layer perspective, we obtain the expressions of interference probability to PUs' and SUs' throughput for both slotted Aloha and distributed coordination function-based Medium Access Control (MAC) protocols. Compared against related contributions, which use detection probability as constraint, we formulate the sensing-throughput tradeoff problem by taking the interference probability as the optimization constraint. We further propose to use the access strategies set and exhaustive search on sensing duration to jointly optimize spectrum sensing parameters and access parameters with the objective of a completely cross-layer design. Numerical results show that the proposed cross-layer method can improve SUs' throughput performance significantly by relaxing the requirement of sensing reliability. Moreover, SUs' throughput performance when the realistic multi-channel scenario is taken into account is worse than the predicted performance in related contributions assuming single-channel scenario. In addition, the optimal solution varies with the number of divided sub-channels and frame duration, and thus needs to be carefully designed.