A slot-asynchronous MAC protocol design for blind rendezvous in cognitive radio networks

In cognitive radio networks (CRNs), two users have to rendezvous on a common available channel before communications. Most existing rendezvous papers focus on the channel-hopping (CH) sequence design. However, rendezvous may suffer from the handshake failure on the rendezvous channel, especially in unsynchronized-slot scenarios. In this paper, the challenge of slot-asynchronous rendezvous in CRNs is addressed for the first time. A protocol aiming to improve the handshake performance during the CH process is proposed. By analyzing the potential factors leading to the handshake failure, we design a novel MAC protocol with an optimal size of a time slot which can mitigate the effects of these factors and provide the shortest time for rendezvous. In addition, we also propose a probabilistic model for estimating the average rendezvous time under different CRNs. Simulation results validate our analytical model and demonstrate that our proposed protocol can achieve the rendezvous time close to the theoretical value under slot-asynchronous scenarios.