Contention based multi-channel MAC protocol for distributed cognitive radio networks

Design of an efficient medium access control protocol is critical for proper functioning of a distributed cognitive radio network and better utilization of the available channels not being used by primary users. In this paper, we design a contention based distributed medium access control (MAC) protocol for the secondary users´ channel access. The proposed MAC protocol allows collision-free access of the available channels and eventual utilization by secondary users, with spectrum sensing part being handled by exclusive sensing nodes. The effectiveness of the proposed MAC protocol is evaluated analytically and also through empirical simulations. We show how the protocol performs with respect to blocking probability, channel grabbing, and channel utilization.