Cooperative rendezvous protocol for multiple user-pairs in cognitive radio networks

In cognitive radio networks, rendezvous is a fundamental operation by which cognitive users establish communication links. Most of existing works consider rendezvous of a pair of users. When multiple pairs of users are doing rendezvous, collisions are caused by the multiple user-pairs which significantly degrade the rendezvous performance, e.g., resulting in a long time-to-rendezvous. To address this problem, we propose a new protocol called Cooperative Rendezvous Protocol which exploits cooperation in the multiple user-pairs environment to speed up the rendezvous operation. Using this protocol, multiple user-pairs cooperate with each other to relay their channel availability information, so that they could avoid attempting rendezvous in unavailable channels. The proposed protocol serves as a general framework that can be applied in conjunction with any existing rendezvous algorithm for faster rendezvous. We theoretically derive an upper bound on the time-to-rendezvous when the proposed protocol is applied in conjunction with any rendezvous algorithm which generates channel hopping sequence based on the available channel set. In addition, we conduct extensive simulation and the results show that the proposed protocol can significantly reduce the time-to-rendezvous of the existing rendezvous algorithms by up to 80.86% in multiple user-pairs environment.