Practical fast multiple radio blind rendezvous schemes in Ad-Hoc cognitive radio networks

摘要

Ad-hoc networks are promising complements for the infrastructure based network under disastrous scenarios. However, due to the heterogeneous surrounding environment of each user, the channel availability of each user may be quite different. Cognitive radio emerges as a promising technology to enable two users to communicate under different channel availability, by opportunistically accessing available channels through dynamically configuring transmission parameters. In a cognitive radio network, secondary users (SUs) need to sense the spectrum to obtain current available channels and have to vacate the occupied channels when primary users (PUs) return. In cognitive radio networks, establishing a link through a common available channel is defined as the rendezvous process between two SUs. Channel hopping is a widely used method to solve the rendezvous problem under which two SUs hop according to a designed channel hopping sequence until they meet on a common available channel. Past works on the rendezvous process focus on designing the channel hopping sequence but ignoring the necessary RTS-and-CTS exchange process to set up a link when two SUs hop to a common available channel, especially when each SU is equipped with multiple cognitive radios. In this paper, we define a new send-or-receive problem regarding the RTS-CTS exchange in a rendezvous process of SUs equipped with multiple cognitive radios. Our proposed blind rendezvous schemes are fully distributed. Simulation results show that our proposed schemes can achieve a fast and guaranteed rendezvous, which is beneficial for quickly setting up communication links under disastrous scenarios.