Priority based MAC scheme for cognitive radio network: A queuing theory modelling

In the cognitive radio networks (CRNs), primary user (PU) has higher priority to access the spectrum band over the secondary user (SU). In this paper, new multichannel priority based cognitive radio (CR) architecture is presented for medium access control (MAC). This multichannel CRN architecture is designed with pre-emptive, non-preemptive resume, and pooling priority based systems. Main objective of this modelling is to minimize the overall transmitting or processing time for all the users. We have derived the optimal system time, waiting time, and channel selection probability (conditional, and unconditional probabilities) for the priority-based spectrum decision schemes. We have also designed and simulated multichannel priority CRN system with various cases, i.e., multichannel with priorities and opportunistic selection of best available channel from multichannel systems. Simulation results and observations verify our mathematical model that, system or processing time depends on the number of users in the system and queue, and number of channels in the CRN system. Moreover, processing time for the primary users is much lower than the secondary users, because waiting time of secondary users is higher than the primary users.