Soft and stable routing protocol for cognitive radio VANETs considering cognitive users mobility

In this paper, a Soft and Stable Routing (SSR) protocol for cognitive radio vehicular ad hoc networks, (CRVANET), is proposed which is robust to cognitive user mobility and primary user activity. Considering primary users activity causes soft spectrum mobility while deploying cognitive users mobility allows stable routing. The protocol allows nodes to collect spectrum information during a spectrum management interval followed by a transmission period. Cognitive users discover routes by joint channel and next hop selection (synchronization) in the transmission intervals. A restricted forwarding strategy is adopted to avoid performance degradation specially due to routing overhead. By considering PU activity SSR selects safe routes against primary users and by considering mobility parameters of cognitive users, the protocol selects stable routes. SSR protocol performance is investigated through simulation in different scenarios and is compared with the modified version of DAODV protocol. The results indicate that SSR can achieve significant reduction in control overhead as well as improving route stability.