OMF-MAC: An opportunistic matched filter-based MAC in cognitive radio networks

Opportunistic spectrum access (OSA) in cognitive radio has been proposed to improve spectrum efficiency in which secondary users (SUs) can access the unused portion of the primary users' (PUs) spectrum temporally or spatially. OSA by multiple SUs is controlled by the medium access control (MAC) protocol. OSA MAC protocols have to avoid or prevent collisions during transmission. In addition, OSA MAC protocols have to deal with the interference between the primary and secondary systems. The key challenge is to provide service to the secondary system while not causing interruption to the primary system. In this paper, we propose an opportunistic matched filter-based (OMF) MAC protocol to jointly consider spectrum access of the idle portion of the spectrum and coordination among SUs. We first model the channel as an on-off process and then apply renewal theory to deal with spectrum access and derive the expression for the expected accumulated interference interval in terms of the transmission time. Using this expression for interference interval, we model the coordination and competition among SUs as a discrete-time Markov chain. We then perform throughput and delay analysis to derive the closed-form expressions for the aggregate secondary system throughput and average secondary packet delay. Finally, we present simulation results to verify our analysis.