A Spectrum-Aware Routing in DOFDM-based Cognitive Radio Ad-Hoc Networks

With the rapid requirement and development of the green ICT (Information and Communication Technology) technology, the demand for dynamically radio spectrum resources has significantly attentions. The low utilization of licensed spectrum leads to the scarcity of the spectrum resource. The emerging cognitive radio (CR) systems become increasingly important in the wireless green communication. In cognitive radio ad-hoc networks, unlicensed users (called secondary users, SUs) communicates with other CR users through an ad-hoc connection on licensed spectrum bands, but spectrum bands may be unexpectedly preempted by licensed users (called primary users, PUs) at any time. The design of routing protocol for cognitive radio ad-hoc network considers problems of the dynamic spectrum sensing, management, sharing, and mobility caused by reappearance of PUs. A cognitive ad hoc network is called as DOFDM-based cognitive radio ad-hoc network if the cognitive ad hoc network is adopted the discontinuous orthogonal frequency division multiplexing (DOFDM) technology. In this paper, we developed a spectrum-aware routing protocol for DOFDM-based cognitive radio ad-hoc networks by using the concept of the minimum expected total transmission time. With the expected total transmission time of all possible paths, a route with the smallest expected total transmission time is constructed. Finally, mathematical analysis and simulation result illustrate the proposed routing protocol can significantly reduce the total transmission time and improve the throughput.