An Interference Alignment Method Based On Stochastic Geometry In Two-tier Networks

In recent years,indoor voice and data services are numerous.At the same time,people's requirements on the data quality of service(QoS)are increasingly high.The traditional macrocell is no longer suitable to meet people's demand for communications data services.How to reduce the communication network energy consumption effectively,and use the spectrum resources efficiently is the next technical problems that operators must solve.Compared with the traditional macrocell network,femtocell is a new network model,with the advantages of small coverage,low power,low cost and the user can install on their own.However,due to the scarcity of spectrum resources,and in order to ensure multiple femtocell QoS in a macrocell Base Station coverage,macrocell and femtocell must share the frequency bandwidth,which will result in co-channel interference problems between macrocell and femtocell Layer.Aim at analyzing the interference problems in the two-tier heterogeneous network constituted by femtocell and macrocell,this paper uses the idea of interference alignment,which is proposed as a new type of interference cancellation method.By setting the beamforming matrix at the transmitting end,the interference of each receiver is aligned into the same interference subspace.In this way,the useful signal can be transmitted in the non-interfering subspace.The full text is summarized as follows:Firstly,the background of the two-tier heterogeneous network is introduced.Secondly,the key technologies of Femtocell and the interference in Femtocell network are introduced.Then,the interference alignment technique and random geometry theory are discussed.In order to eliminate the interference under the dense deployment of femtocell,this paper proposes a clustering interference alignment method based on K-Medoids algorithm in two-layer network.This paper considers the three-dimensional femtocell network structure model,especially the femtocell network model which conforms to the 3D Poisson Point Process distribution.Then,the K-Medoids algorithm is used to cluster the femtocell.Finally,the interference alignment technique is used to eliminate the interference of the same layer in each cluster,which reduces the complexity of interference management and is suitable for the actual communication system.In order to reduce the processing overhead and improve the performance of the interference alignment,this paper proposes an interference alignment scheme based on precoding and user scheduling.Firstly,the stochastic geometric theory is used to model the network.Then,the user scheduling is performed based on the Signal to Leakage plus Noise Ratio(SLNR)algorithm,and the user set of each base station is obtained.Lastly,the base station eliminate the uplink interference from other users which is based on the interference alignment algorithm of the maximum SLNR.Simulation results show that the proposed algorithm has large improvement on the system capacity compared with the traditional scheme.