CR-CSMA: A Random Access MAC Protocol for Cognitive Radio Networks

In this paper, we consider the medium access control (MAC) protocol design problem for random access cognitive radio networks. A MAC protocol using a two-level opportunistic spectrum access strategy, called CR-CSMA, is proposed to efficiently schedule secondary users' packets, and yet to protect primary users' operations. We employ normalized throughput and average packet delay as network metrics, and derive closed-form expressions to evaluate our protocol. For various offered traffic rates of secondary users and frame lengths, the optimal performances of secondary users can be achieved at the same spectrum sensing time, and also there exists a tradeoff between performance and agility.