Research On Power Control Technologies In Macrocell/Femtocell Heterogeneous Networks

The weak coverage of indoor wireless signals always a major problem for high-speed mobile communication systems,and the introduction of Femtocell is one way to solve this problem.However,deploying Femtocell in a Macrocell network constitutes a two-tiered heterogeneous wireless network that creates severe cross-layer interference and peer-to-peer interference in a co-channel scenario.In this paper,the power control technology as a starting point for the Femtocell base station(FAP)and the user's launch power and other issues to explore to overcome the heterogeneous network uplink and downlink between the various types of interference solutions.The main contents are as follows:Firstly,analyzing three kinds of access methods,such as open access,closed access and hybrid access in heterogeneous networks.The problem of the same layer interference and cross-layer interference under different interference scenarios is analyzed.Then put forward the appropriate solution for the corresponding interference problem.The interference avoidance,interference elimination,interference coordination three interference management technology is briefly introduced.In addition,the basic concepts and requirements of power control technology are briefly introduced,and several typical power control technology algorithms are discussed and compared.Secondly,for the heterogeneous networks downlink cross-layer interference problem,using the method of transmitting power control to FAP,it reduces the strong interference of Macrocell users(MUE)at Femtocell network edge.By comparing the SINR of the Femtocell users(FUE)and the MUE with the minimum SINR threshold,the FAP transmit power adaptive adjustment algorithm is proposed.This method uses the measurement of FUE path loss,which minimizes the transmission power of FAP under the condition of satisfying the QoS requirement of FUE and guaranteeing the minimum SINR threshold of FUE.The method improves the communication quality of MUE as much as possible under the condition of satisfying the QoS requirement of FUE and ensuring the minimum SINR threshold.The simulation results show that the proposed method can effectively reduce the interference of MUE and improve the overall performance of the network.Finally,for the heterogeneous networks uplink cross-layer interference problem,by controlling and adjusting the transmit power of MUE located around FAP and authorized FUE,reducing the strong uplink interference generated by the MUE on its nearby FAP.Through analyzing the non-cooperative powercontrol algorithm based on game theory in the two-tier Femtocell networks,it is found that the transmit power of MUE and FUE is at the Nash equilibrium point,and there are still many FUE SINRs that can not meet the minimum SINR threshold.Therefore,an improved power control method is put forward,in thetraditional non-cooperative power control method,the MUE link quality protection algorithm based on FUE-SINR is proposed by user selection and channel redistribution,which can guarantee the target SINR of the MUE,and make as many as possible FUE to achieve their target SINR.The simulation results show that the proposed method not only improves the communication quality of the edge Macrocell users located around the Femtocell network,but also reduces the number of Femtocell users who can not meet the SINR threshold conditions.