Channel dynamics matter: Forwarding node set selection in cognitive radio networks

Opportunistic routing is very promising when applied to cognitive radio networks (CRNs). However, this requires solving the forwarding node (FN) set selection problem for each node in CRNs. The FN set selection is different from that in traditional networks because the reliability under suddenly active primary users (PUs) and the co-channel interference have to be taken into account. Moreover, the selected FN set cannot stay static in CRNs due to the dynamic channel environment. It means that an adjustment scheme of the FN set is necessary. We construct a FN set selection model for CRNs, which prioritizes each FN candidate considering not only its ETX metrics, but also the channel dynamics and co-channel interference. Based on the defined priorities of each node, we propose three algorithms, a basic greedy algorithm, a greedy algorithm with one backtrack, and a maximum weighted independent set (MWIS) algorithm, for FN set selection aiming at different performance requirements. Extensive simulations are performed to evaluate our FN set selection algorithms.