Abstract : In emerging small cell wireless, each femtocell access point (FAP) can either service its home subscribers exclusively (i.e., closed access) or open its access to accommodate a number of macrocell users so as to reduce cross-tier interference. In this paper, we propose a game-theoretic framework that enables the FAPs to strategically decide on their uplink access policy. We formulate a noncooperative game in which the FAPs are the players that want to strategically decide on whether to use a closed or an open access policy in order to maximize the performance of their registered users. Each FAP aims at optimizing the tradeoff between reducing cross-tier interference, by admitting macrocell users, and the associated cost in terms of allocated resources. Using novel analytical techniques, we show that the game always admits a pure strategy Nash equilibrium, despite the discontinuities in the utility functions. Further, we propose a distributed algorithm that can be adopted by the FAPs to reach their equilibrium access policies. Simulation results show that the proposed algorithm provides an improvement of 85.4% relative to an optimized open access scheme in the average worst-case FAP utility.
