Rendezvous In Cognitive Radio Ad-Hoc Networks With Channel Ranking

In distributed cognitive radio (CR) networks, rendezvous (RDV) is one of the most critical issues. Due to the dynamic radio environment, achieving RDV on a predetermined common control channel (CCC) is a challenging task. Channel hopping (CH) provides an effective method to guarantee RDV in cognitive radio ad-hoc networks (CRAHNs). Most of the existing CH schemes utilize the channel quantity as an input to the family of mathematical concepts such as prime number theory, Chinese remainder theory (CRT), quorum system and combinatorial block design to achieve RDV. However, RDV on a channel is rather influenced by channel quality or CR user's preference on which it wants to achieve RDV on available channels. Based on this philosophy, a channel rank based torus quorum CH RDV protocol (TQCH) is proposed which finds a commonly available channel between a pair of CR nodes. We formulate the channel ranking as a linear optimisation problem based on the channel availability under collision constraints. A detailed mathematical formulation is derived to estimate the degree of overlap in terms of expected quorum overlap size. Simulation results show that the proposed TQCH scheme outperforms than that of other CH schemes in terms of average time-to-rendezvous (ATTR) and the degree of overlap in asymmetric channel scenario.