A Fully Distributed Game Theoretic Approach to Guarantee Self-Coexistence among WRANs

Although the proliferation of wireless applications operating in unlicensed spectrum bands has resulted in overcrowding, recent analysis has shown that license bands are still underutilized. Cognitive Radio is seen as the key enabling technology to address the spectrum shortage problem, opportunistically using the spectrum allocated for TV bands. In this paper, we present a novel game theoretic framework that uses the potentialities of the new IEEE 802.22 Standard to guarantee self-coexistence among Wireless Regional Area Networks. We address this problem as a channel assignment problem where each WRAN acquires a chunk of spectrum free of interference in a dynamic and distributed way. Using a novel technique to compute backoff windows, we show that the channel assignment problem can be formulated as a multi-player non-cooperative repeated potential game that converges to a Nash Equilibrium point. We consider each WRAN as a player of our game and we use two different types of utility functions to maximize the spatial reuse and minimize the interference. An extensive simulation study shows that having the interference minimization as objective is not necessarily the best solution with selfish players.