On Cooperative Channel Rendezvous in Cognitive Radio Networks

In cognitive radio (CR) networks, establishing communication sessions requires the communicating pairs to meet each other on a common channel via a “rendezvous” process. Designing distributed rendezvous protocols without common control channels is a challenging problem due to the dynamic and opportunistic spectrum access paradigm. The existing protocols, mainly based on channel hopping, suffer from the rendezvous difficulty due to asymmetric channel perceptions and significant rendezvous delay when the system scales. In this paper, we exploit a long-neglected opportunity for enabling rendezvous in CR networks-the cooperation among cognitive users. We develop a novel cooperative rendezvous mechanism by introducing the cooperative cognitive nodes serving as “bridges” between communicating pairs to facilitate their rendezvous process. We establish a mathematics framework to study the rendezvous delay and robustness and derive the performance limit in asymptotic scenarios. Our analytical results are further confirmed by the simulation results showing the performance improvement of the developed cooperative rendezvous protocol with only small overhead.