Energy-Efficient Power Optimization In Two-Tier Femtocell Networks

With the development of wireless communication technology and mobile Internet, the demand for mobile communication services is growing. Recent research has shown that most of mobile communication services take place in indoor environments. As one of the most promising technologies for indoor wireless communications, femtocells have attracted much attention. Femtocells are short-range, low-power and low-cost home base stations deployed by the terminal consumer and operate in licensed spectrum. Femtocells are connected to the operator’s network via broadband connections such as digital subscriber line (DSL) or cable modem. Femtocells can provide better indoor user experience with lower transmit power, resulting in power saving of mobile devices. Femtocells can offload traffic from macrocells, consequently improving the network coverage and capacity.However, cross-tier and co-tier interference may greatly impair network performance of spectrum-sharing femtocell networks and it will consume large amounts of energy for large scale application. This motivates the use of power optimization for interference management in two-tier femtocell networks. In this paper, we propose an energy-efficient power optimization scheme for the uplink transmission of a spectrum-sharing femtocell network based on game theory, where both circuit and transmission powers have been considered. Each user announces a price that reflects its sensitivity to the current interference level, and adjusts its power to maximize its utility. Furthermore, we propose a simple macrocell link protection scheme, where a macrocell user (MUE) can protect itself by increasing its price. That is, the femtocell user (FUE) that causes more interference to macrocell base station (MBS) will pay more for its interference.In this paper, we have analyzed the interference in the two-tier femtocell network and establish the system model through MATLAB. The scheme is proved to converge to a unique optimal equilibrium. According to numerical results, the proposed scheme can protect the macrocell user’s target Signal-to-Interference-plus-Noise Ratio (SINR) while improve the energy efficiency significantly.