A Stable Path Routing Protocol for Cognitive Radio Ad hoc Networks based on the Maximum Number of Common Primary User Channels

We propose a novel local spectrum knowledgebased distributed stable path routing protocol for cognitive radio ad hoc networks (CRAHNs) where the unlicensed secondary users (SUs) make use of the licensed channels of the Primary Users (PUs) when the latter are not actively using the channels. We model a time-variant CRAHN of SUs with links between any two SUs if they have at least one common PU channel available for use in their neighborhood and the weight of an edge is the number of such common PU channels available for use. Referred to as the Maximum Common Primary User channel-based Routing (MCPUR) protocol, the proposed protocol prefers to choose an SU-SU source-destination (s-d) path with the largest value for the sum of the number of common PU channels available for use across each of its constituent edges. Our hypothesis is that such an s-d route is likely to exist for a longer time (and incur fewer broadcast route discoveries) as the end nodes of the constituent SU-SU edges are more likely to have at least one common available PU channel that can be used to complete the transmission and reception of data packets. Simulation results confirm our hypothesis to be true: the number of path transitions incurred with MCPUR could be at most 62% lower than that of the path transitions incurred with a minimum hop-based shortest path routing (SPR) protocol. The tradeoff is a low-moderate increase in the hop count per path (as large as 17%).