| In recent years,a large number of low power base stations(nodes)are introduced to form Tiered-heterogeneous networks on the basis of macro base stations in order to meet the growing needs of users.However,the frequency reuse between macro base stations and low power base stations causes serious interference when increasing the transmission rate.Interference has become one of the main obstacles to the improvement of network performance.Analysis and suppression of interference can significantly improve the signal transmission quality and user satisfaction.Therefore the analysis of interference has always been the focus of academic research.For further optimizing the heterogeneous networks,we need to establish a more practical theoretical model to study the interference,analyze the interference performance of different scenarios and different configurations,as well as the corresponding signal processing.This dissertation proposes a interference analysis,which combines network topology,node density,transmit power,wireless fading and cooperative beamforming techniques,as follows is idiographic research:Firstly,modeling and analysis the the downlink interference performance of double-layer heterogeneous cellular networks by random geometry,and evaluate the influence of fading characteristics,transmit power,node density and other important parameters on the interference and network performance.Secondly,Since the edge users receive the weakest signal from the central base station and they are most vulnerable to be interfered with other adjacent cells.Furthermore,the performance of the system will be greatly affected by the edge users,thus the downlink interference elimination and analysis based on cooperative beamforming of the edge users are researched implemented in this dissertation.The interference performance is characterized by coverage probability,and the effects of cooperative beamforming and number of base station antennas and SIR threshold on interference performance are analyzed. |
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