Carrier sensing based multiple access protocols for cognitive radio networks

Cognitive radio (CR) dynamically accessing inactive radio spectrum of the primary system (PS) at link level has attracted a lot of research interests. The cognitive radio network (CRN) organized by multiple CRs has been considered as an emerging wireless communication technology. In order to efficiently utilize the radio spectrum, the multiple access schemes of the CRN shall be considered together with physical layer (PHY) transmission schemes. In this paper, we propose a novel class of carrier sense multiple access (CSMA) based MAC protocols for the CRN while the PS is also operating with widely-applied carrier sensing protocols. Different from conventional CR either to transmit packets or not, our protocols with a feasible adaptive PHY transmission scheme allow possible transmission(s) for a CR even when the PS is actively transmitting. We analyze the proposed class of CSMA based MAC protocols and further propose the transmission strategy for each CR to improve the throughput of the CRN. Numerical results show that our proposed scheme improves the throughput of the CRN more than 36% and 100% as compared with the conventional CSMA and conventional CR operations, respectively.