A cluster-based link recovery mechanism for spectrum aware on-demand routing in cognitive radio ad hoc networks

In cognitive radio ad hoc networks (CRAHNs), link failures among secondary users (SUs) primarily result from sudden appearance of primary users (PUs). In tradition, route recovery generates much packet loss before the routes are recovered completely. Recent researches on route recovery process in CRAHNs mainly adopt on-demand route maintenance protocols in wireless networks. This paper proposes a clusterbased link recovery mechanism (CLR) in CRAHNs. CLR recovers failed links locally and does not change the original routes. Since the routes have not been changed, the data packets are able to be cached in the buffer. Data packets can be sent after the links are recovered and hence decreases the amount of packet loss. If there is an intersection area of all PUs' radio coverage in the network with some SUs existence in the area, links between these SUs are apt to break no matter what channels these SUs choose. CLR recovers all link failures by using clustering method and effectively increases end-to-end throughput and successful packet delivery fraction. The simulation results indicate that CLR increases successful packet delivery ratio and end-to-end throughput. The performance is much superior particularly if there is an intersection area of all PUs' radio coverage in the network.