Channel Selection among Frequency-Agile Nodes in Multihop Wireless Networks

Radio frequency (RF) spectrum is a scarce resource from the perspective of allocation; in the U.S., almost all RF spectrum has already been allocated for specific uses. Much of this allocated spectrum, however, remains idle for large portions of time, and thus RF spectrum is actually a plentiful resource from the perspective of occupancy. Accommodating new wireless services and technologies will require loosening of restrictions on the use of allocated spectrum and sharing of this spectrum among many different types of users. We consider opportunistic use of RF spectrum and in particular the problem of finding communications channels for a group of opportunistic users intending to form a network. The procedure for selecting channels as well as opportunistic use of them should cause minimal interference for primary users and their clients and should not require a preexisting control channel. We provide a simple, distributed algorithm that satisfies these goals, to be executed by the opportunistic users for advertising and negotiating channels, and we illustrate its behavior through simulation and analysis.