ZOS: A Fast Rendezvous Algorithm Based on Set of Available Channels for Cognitive Radios

In cognitive radio networks, rendezvous is a fundamental operation by which cognitive users establish a communication link on a commonly-available channel for communications. Most of existing rendezvous algorithms provide guaranteed rendezvous (i.e., rendezvous can be achieved within finite time) by generating channel-hopping (CH) sequences based on the whole channel set. These algorithms are inefficient when available channels account for a small proportion of the whole channel set. Some recent algorithms generate CH sequences based on the available channel set. However, these algorithms normally require additional information such as unique IDs and predefined roles of cognitive users. In this study, we design a new algorithm called ZOS based on the set of available channels without any additional requirements. ZOS uses three types of elementary sequences (namely, Zero-type, One-type, and S-type) to generate CH sequences and provides guaranteed rendezvous. The maximum time-to-rendezvous of ZOS is upper-bounded by -boldsymbol{O}(-boldsymbol{m}-{1}-times -boldsymbol{m}-{2}-times-mathbf{log}-{2}-boldsymbol{M}) where -boldsymbol{M} is the number of all channels and -boldsymbol{m}-{1} and -boldsymbol{m}-{2} are the numbers of available channels of two users. Simulation results show superior performance of ZOS.