Study On Power Control And Interference Management In Two-Tier Femtocell Networks Based On Game Theory

Femtocell, also called as femtocell base station, home base station is a low power femtocell installed in indoors. Femtocell technology has developed rapidly in recent years for increasing cellular network coverage and reducing costs. Game theory is a mathematical theory for the study of the decision-making with struggle or the competition. Non-cooperative game emphasizes the individual independent decision which is unrelated with other players’ strategies. In two-tier femtocell networks, spectrum sharing, limited access and unplanned network deployment lead the serious cross-tier interference. Network resources can be allocated in a distributed manner by non-cooperative game, which decreases the exchange of the information and reduces the network overhead. At present, there are some researches focused on the power control and interference management in the wireless cellular network. But it still necessary to build the reasonable network scenario and design a more rational resource allocation and interference management mechanism.Firstly, we study the power control problem in two-tier femtocell networks. The relationships between the macrocell base station and femtocell users’ SINR(Signal to Interference and Noise Ratio) are investigated based on the theory of the spectrum radius. With the obtained comparison results, we propose two different power control schemes: minimum power control scheme and distributed power control scheme based on Stackelberg game. The two power control schemes are effectively suppress the cross-tier interference with low power consumption. To achieve a more rational use of network resources, an admission control method is also introduced. Simulation results show that the power control scheme can significantly reduce power consumption of the femtocell users in dense femtocell networks.Secondly, in two-tier femtocell networks, the pricing mechanism has become an effective tool in resource allocation and interference management. Integrating the utilities of the macrocell base station and the femtocell users, we propose two pricing schemes: uniform pricing scheme and non-uniform pricing scheme. The two pricing schemes effectively suppress the cross-tier interference, while ensuring the optimal power allocation. Simulation results show that the quality of service of all femtocell users have been greatly improved. In addition, it also shown that the uniform pricing scheme and non-uniform pricing scheme respectively have their own superiorities in different aspects of the network performance.Finally, based on the previous work, the integrated utility optimization are presented to restrict the cross-tier interference and the “near-far effect” in CDMA system. Considering the different access priorities and service needs of the users, the power control scheme is proposed based on the hierarchical game. In addition, an efficient and adaptive pricing scheme is designed based on the real-time interference. At last, a two-step admission control scheme is introduced to protect the network performance. The simulation results show that the hierarchical game method can achieve the optimal transmit power allocation. Besides, femtocell users’ SINR can be effectively improved with the adaptive pricing scheme.