Comprehensive asynchronous symmetric rendezvous algorithm in cognitive radio networks

Spectrum has become a scant quantity with recent upsurge in the field of wireless communication. Cognitive radio network (CRN) alleviates the overgrowing spectrum scarcity and underutilization problem by adequately sharing the frequency bands between licensed and unlicensed users. CRN allows unlicensed users or secondary users (SUs) to opportunistically utilize the free portion of the spectrum allocated to the licensed users or primary users. The fundamental process in the formation of CRN is the rendezvous process where SUs meet on commonly available channels and establish reliable links for effective communication. Existing rendezvous solutions based on the assumption of a common control channel (CCC) among the SUs are infeasible and less efficient in the dynamic environment of CRNs. Therefore, channel hopping (CH) technique without CCC support, often referred to as blind rendezvous, is usually employed for accomplishing the rendezvous between SUs. This paper presents a comprehensive asynchronous symmetric rendezvous (CASR) algorithm that does not require time synchronization and guarantees rendezvous of SUs in finite time. CASR algorithm exploits the MAC address of SU as the unique identifier (ID) and generates CH sequence based on the dynamic manipulation of ID according to the number of available communication channels. Leveraging the unique ID of each SU, CASR algorithm succeeded in rendezvous guarantee while perpetuating a good time to rendezvous. The efficiency of CASR algorithm is estimated theoretically and verified through various simulation experiments. Simulation results affirm that CASR algorithm performs better in terms of average time-to-rendezvous as compared with existing rendezvous algorithms.