Factor graph-based distributed frequency allocation in wireless sensor networks
Panos N. Alevizos, Efthymios A. Vlachos, Aggelos Bletsas · 2014
As wireless sensor networks (WSNs) become denser, simultaneous transmissions (on the same time slot and frequency channel of two or more terminals) may cause severe interference. Appropriate interference-aware allocation is a complex problem and distributed frequency allocation is even harder. This work studies the problem of assigning frequency channels for a given WSN routing tree, such that: a) time scheduling and frequency allocation are performed in a distributed way, i.e. information exchange is only performed among neighboring terminals, and b) detection of potential interfering terminals is simplified. The algorithm imprints space, time and frequency constraints, assuming half-duplex, single-antenna radios into a loopy factor graph (FG) and performs iterative message passing. Convergence to a valid solution is addressed based on appropriate modifications of the resulting message passing inference algorithm. The proposed algorithm is compared with two distributed frequency allocation algorithms, based on game-theory or min-max interference control. It is shown that the proposed distributed algorithm offers comparable performance with state-of-the-art, even though it utilizes simplified interfering terminals set detection.