A Slow Hopping MAC Protocol for Coordinator-based Cognitive Radio Network

Abstract

Many opportunistic spectrum access MAC protocols for cognitive radio networks have been proposed to allow coexistence of both primary and secondary users in licensed bands. However, most of the proposed approaches are based on common control channel that may become a bottleneck for data transfer, as well as be prone to jammer or primary user activity. We propose a coordinator-based cognitive radio network and an opportunistic spectrum access MAC protocol using slow hopping, SH-MAC, to achieve robustness to primary user or jammer activity as well as aggregate throughput improvement. The coordinator considers primary user activity identification, spectrum sensing, channel hopping scheduling, and network time synchronization. The proposed MAC protocol includes mechanisms such as network joining, two-level CS-MACA operation, on-time channel switching, returning to common hop to run in the slow hopping and coordinator-based network environment. Furthermore, the proposal is devised for secondary users to operate with only one transceiver that has non-negligible switching overhead. We validate our protocol using simulation. Simulation results show SH-MAC efficiently increases network capacity regardless of PU activity over the licensed channels.