Ring-Walk Based Channel-Hopping Algorithms with Guaranteed Rendezvous for Cognitive Radio Networks

Rendezvous is a fundamental and essential operation for users of cognitive radio networks (CRNs) to meet and establish a link on a common channel, so that information exchange and data communication can be carried on. This work addresses the problem of blind rendezvous, i.e., rendezvous without the help of any central controller and dedicated common control channel. We propose two ring-walk (RW) based channel-hopping (CH) algorithms. The basic idea is to represent each channel as a vertex in a ring. Users "walk" on the ring by visiting vertices of channels with different velocities. Rendezvous is achievable since the user with lower velocity will eventually be "caught" by the user with higher velocity. Compared with the existing solutions, our algorithms achieve the following advances: i) guaranteed rendezvous without the need of time-synchronization, ii) applicability to rendezvous of multi-user and multi-hop scenarios. We derive the maximum time-to-rendezvous (TTR) and the expected TTR of our algorithms in both 2-user and multi-user scenarios (shown in Table I). Simulation results show superior performance of our algorithms.