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A cognitive radio performs spectrum sensing, so that the device is able to self-organize appropriate networking functions. Rendezvous is the process by which the nodes explore the available channels to establish a link when they want to communicate with each other. Although using a dedicated control channel can be a solution to find the common control channel, it may result in a bottleneck and create a single point of failure. In this paper, we propose an asynchronous channel hopping sequences to establish a link in self organizing cognitive radio networks without the assumption of global clock synchronization. Our scheme provides successful communication rendezvous within a bounded time interval. Theoretical analysis and simulation results showed that our scheme outperforms the existing asynchronous schemes used for similar purpose in terms of many performance criteria.

Cognitive Radio (CR) technology has emerged as a suitable technology for providing a possible solution to the lack of the spectrum problem. For this, CR has to identify opportunistically and heuristically the available spectrum, in which primary users (PUs) do not exist on it. It is critical that the secondary users (SUs) use the vacant portions of the spectrum without causing a loss of efficiency for PUs and without any interference effects on PUs in CR networks. Among the recent research on CR MAC protocols, we focused on the selection of rendezvous channel (RC), which is the core of the Cognitive MAC (C-MAC) protocol. In this paper, we propose a new RC selection scheme that can always maintain only one RC at a certain time. The design and performance of our scheme is presented and evaluated in this paper.