Spectrum sharing and energy-efficient power optimization for two-tier femtocell networks

Two-tier femtocell network is considered a promising solution for the rapidly rising mobile data rate demand due to its high spectrum efficiency. However, underlaying femtocells with macrocells will result in co-channel interference (CCI) which severely deteriorates network performance. Therefore, optimized power control is required in femtocell network to avoid such interference. Additionally, energy efficiency of cellular network is becoming increasingly important under current trend of green communication. Thus, in this paper, we propose an energy efficient power control algorithm for femtocell network. Our proposed model is based on Stackelberg game, in which macro base station (MBS) acts as leader while femto base stations (FBSs) act as followers. MBS adjusts its power and imposes interference price on femtocells to maintain its user´s minimum rate requirement and earns revenue. Subsequently, FBSs optimize their power based on the imposed price which takes into account the cost of both spectrum sharing and energy usage. Two cases, namely uniform and non-uniform pricing are considered. And an iterative algorithm which converges rapidly is also proposed to calculate the interference price and power allocation strategy in the two cases. Finally, our model is validated by simulations and the results show the superior performance of our schemes over existing one.