Hierarchical-Game-Based Uplink Power Control in Femtocell Networks

Femtocells are viewed as a promising option for mobile operators to improve coverage and provide high-data-rate services in a cost-effective manner. However, cross-tier interference mitigation is considered to be one of the major challenges. Distributed-game-based power control approaches are effective for interference management in wireless networks. In this paper, we focus on the optimal power allocation for uplink transmission in two-tier femtocell networks and take into account the different service requirements and design objectives of macrocell user equipment (MUE) and femtocell user equipment (FUE) devices. The framework of hierarchical game with a multiple-leader-multiple-follower model is adopted to investigate the uplink power allocation problem. By using hierarchical game, on one hand, the utilities of both MUE and FUE devices are maximized; on the other hand, the uplink protection of MUE devices is highlighted. To obtain the game equilibrium (GE) distributively, we develop the iterative power update rules for both MUE and FUE devices. Moreover, given channel uncertainty, a robust hierarchical game is formulated and solved distributively. For implementations, the running process of the proposed hierarchical games is analyzed in detail. Finally, numerical results show the convergence of the hierarchical games without and with channel uncertainty. Moreover, it is also demonstrated that, in either case, the GE is unique and that the game is effective.