An efficient broadcasting scheme for cognitive radio ad hoc networks

Cognitive radio (CR) enables efficient sharing of radio spectrums, where those spectrums are owned by licensed users which are named as primary users (PUs). As in conventional ad hoc networks, broadcasting is also a necessary and an elementary operation in cognitive radio ad hoc networks (CRAHNs). In CRAHNs, sharing licensed channels with PUs and rendezvousing in the same channel create extra difficulties for broadcasting. In this paper, we propose a broadcasting strategy for CRAHNs named as "Primary User Aware, Request for Message" (PA-RfM). In the PA-RfM scheme, to prevent the interference with PUs, each broadcasting node calls its neighbors to the licensed data channel with the lowest PU activity. To increase the reachability, when a node cannot get an expected broadcast message due to collisions, it requests this message from a proper neighbor. The algorithm also uses a counter based mechanism to avoid transmissions of unnecessary broadcasting messages. Experimental results show that the PA-RfM strategy can reach 100% of nodes and outperforms possible broadcasting techniques in reduction of the overhead in the network and decreasing propagation delay of broadcasting messages.