Sensing-Throughput Tradeoff of Relay-Assisted Random Broadcast based Cognitive Radio Networks

Random broadcast has been advocated as an effective approach to message sharing among the secondary users (SUs) in the distributed cognitive radio networks (CRNs). However, it is always assumed that if a message is received, it can be received by all SUs in CRNs. The real performance of message sharing and the scheme designing in practice are still unclear. In this paper, we consider a cluster-based distributed CRN, in which the broadcasts of SUs are restricted within clusters and as a result there is no message sharing among clusters. To overcome this, we propose a relay-assisted random broadcast scheme, and introduce the message sharing probability to quantify its performance. We then employ the proposed scheme for cooperative spectrum sensing, and study the sensing-throughput tradeoff problem. Simulations show that the proposed scheme achieves substantial performance improvement on message sharing. Moreover, when given total frame duration, both the sensing performance optimization and the average throughput maximization can be achieved by properly distributing the durations of the primary signal detection, the message sharing via random broadcast and the data transmission.