Spectrum Access Scheme In Cognitive Radio Networks Based On BCR-MAC Protocol

The high data rate demands of modern wireless applications have resulted to aproblem of scarcity of spectrum. In order to increase the spectrum usage efficiency, newpolicies that suggest the coexistence and share of resources between primary users (PUs)and secondary users (SUs) have emerged.Cognitive radio (CR) has received considerableattention as a potential method to allow dynamic spectrum access in wireless networks toimprove spectrum usage. Coordination and communication over wireless medium is carriedout on medium access control (MAC) layer for effective deployment of distributedCognitive radio network.Certainly one of the main factors in spectrum allocation in cognitive radio network ishow to access the spectrum and also the way secondary user‘s link is preserved. In ourthesis the objective is to establish various MAC alternatives for this technology based onBCR-MAC protocol. This method is prone to identification of errors, for instance, falsealarm and misses detections.Backup Channel Reservation-Medium Access Control (BCR-MAC) protocol isemployed in this thesis to achieve settlement for the hanging secondary user link (SUL) inorder to evade collision with the arrival of primary user. The recent concept of BCRprotocol is choosing channels in accordance with different criteria which includeoccupation ratio, current state of channel, residual free time and release time. It also offersefficient secondary user link sustenance and minimizes interference to both users (PU&SU). Moreover it provides alternative for all sizes of data packets.Simulation results achieved using MATLAB and Network simulator has proven therobustness of BCR-MAC protocol.