Priority-based variable multi-channel MAC protocols in cognitive radio wireless network: A fair channel access strategy

This paper presents a priority-based opportunistic multi-channel medium access control (MAC) protocols in cooperative cognitive radio (CR) wireless networks, which used to promote the utilization of radio spectrum resources and to address the fairness issue of channel access among secondary users (SUs). On the one hand, we make use of Markov chain to prioritize each data channel that licensed to the primary users (PUs) according to the data channel´s utilization, that is, when one data channel´s utilization is lower, then its priority is higher, and vice versa. On the other hand, to ensure fairness, we prioritize the secondary users in the light of their contribution to cooperative spectrum sensing and their amount of traffic as well as the traffic´s urgency. Then in the channel competition period, secondary users with higher-priority will get a shorter contention window (CW) and select the lower utilization (that is, higher-priority) channels for data transmission, and vice verse. Simulation results show that our proposed strategy can not only ensures the fairness issue of channel allocation among secondary users but also increases the network throughput without leading to deterioration of the delay-QoS.