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.