Opportunistic Routing in Cognitive Radio Networks: Exploiting Spectrum Availability and Rich Channel Diversity

Designing an appropriate routing metric in cognitive radio networks (CRNs) is a challenging problem. In a multi-hop CRN, both spectrum handoff (quantified by channel availability time) and required transmission time can significantly impact network connectivity and routing. Specifically, spectrum handoff can cause a significant degradation in CRN performance when the availability time of an assigned channel is smaller than the required transmission time over that channel. In this case, the percentage of CR transmissions that will be terminated due to primary user (PU) activities, can significantly increase, leading to a reduction in network throughput. To reduce the percentage of terminated CR transmissions, we introduce a novel routing metric that jointly considers spectrum availability time and required CR transmission time. Based on this metric, we propose a probabilistic routing algorithm for multi-hop CRNs that attempts at computing the path with the maximum probability of success from a given source to its destination (including the channel assignment along that path). Simulation results show that our proposed algorithm leads to a significant performance improvement over two reference algorithms presented in this paper.