Periodic channel-hopping sequence for rendezvous in cognitive radio networks

Abstract

Cognitive radio networks (CRNs) is an emerging paradigm to exploit the spectrum holes very intelligently. To start communication in CRNs, users need to establish a link on a channel which in not occupied by licensed user. Rendezvous is an essential operation in cognitive radio networks (CRNs) to establish a link on common channel for data communication and control information exchange. To achieve guaranteed rendezvous in finite time, most of the proposed algorithms generate channel hopping (CH) sequence using all channels regardless of their availability. Thus, the CH sequence without considering channel availability information may attempt to achieve rendezvous on unavailable channels that result longer time to rendezvous (TTR). The implementation of rendezvous processes in order to minimize the TTR is a major challenge in CRNs. Most of the reported schemes on rendezvous are based on central controller or utilize common control channel this may not be always possible in CRNs. In this paper, we consider the blind rendezvous problem, which find common channel without any central controller. We propose a guaranteed, distributed rendezvous algorithm which finds a commonly available channel for two users called as Periodic Channel Hopping (PCH) sequence algorithm. Our PCH scheme considers only the channels those are free from licensed users. The maximum time to rendezvous (MTTR) and expected time to rendezvous (ETTR) of our PCH scheme are reduced to (2M − 1) and (M − 1) respectively in symmetric model that is better as compared to other competitive schemes. In an asymmetric case, the proposed scheme guarantees rendezvous and MTTR is bounded by M(2M − 1).