Efficient uplink power control in multi-service two-tier femtocell networks via a game theoretic approach

In this paper the problem of efficient power allocation in the uplink of two-tier closed-access femtocell networks is addressed. The modeling and design approach we follow considers two different dimensions, along with the corresponding constraints and properties that stem from each one of them: a) the two tier architecture, and b) the simultaneous support of both real-time and non-real time services with various and diverse Quality of Service (QoS) prerequisites. To treat the above problem under a common framework, network utility maximization theory is used, where each mobile user, either in a femtocell or in the macrocell, is associated with a properly defined QoS-aware utility function. To further mitigate the intercell and cross-tier interference and give higher priority to the macrocell users (MUs), the femtocell users (FUs) are also “penalized” through a convex cost function with respect to uplink transmission power. Due to its nature, the overall resulting problem is formulated as a non-cooperative game, and is solved using the supermodularity theory towards determining a Nash equilibrium point. A distributed iterative algorithm is also proposed in order to obtain the game's equilibrium point. Finally, the operational effectiveness of the proposed approach is evaluated through modeling and simulation, while its superiority against other power control frameworks in two-tier femtocell networks proposed in the literature, is illustrated.