Research On Interference Management In Heterogeneous Cellular Networks Based On Stochastic Geometry

In the current heterogeneous cellular network,interference is a major factor limiting its performance improvement,so it is urgent to manage it effectively.This thesis proposes an interference management strategy based on exclusion region for different types of communication in downlink heterogeneous cellular networks,and establishes a network model matching the proposed strategy by utilizing stochastic geometry theory to fully evaluate its effectiveness.The specific contents are as follows:Firstly,in the heterogeneous cellular network composed of device-to-device(D2D)and traditional cellular communication,this thesis proposes an interference management strategy based on the exclusion region to suppress the interference of D2 D and cellular users when D2 D communication share spectrum with cellular communication.On this basis,a hybrid spectrum allocation scheme is considered,that is,an independent spectrum is allocated to the edge users outside the exclusion regions to further suppress the interference from D2 D communication.Based on the proposed strategy,the base stations and D2 D transmitters are modeled as Poisson point process and Poisson hole process,respectively.However,the latter is not independent of each other in spatial distribution,so it is difficult to accurately analyze the node interference from the modeling point process.Therefore,the theoretical bounds and approximate results of the success probabilities of the central and D2 D users under the two spectrum schemes are derived,as well as the exact results of the edge users under the hybrid allocation and the theoretical bounds under the sharing spectrum.Based on the above results,the area spectrum efficiency of the network is further analyzed.The results show that the proposed strategy can effectively suppress the mutual interference between D2 D and cellular communications under the two kinds of spectrum allocation.Secondly,the idea of interference management based on exclusion region is further applied to the heterogeneous cellular network composed of unmanned aerial vehicles(UAVs)and ground base stations to reduce the mutual interference between UAV and ground cellular communication.In order to evaluate the effectiveness of the proposed strategy,the ground base stations and the projections on the ground of UAVs are modeled as Poisson point process and Poisson hole process respectively,and the theoretical bound and approximate performance analysis method are given.Specifically,two cases of UAV service users are considered,that is,the UAVs serve the user directly above it through the line-of-sight link,and the UAV hovers at a random height and the user being served is connected to the UAV with the closest horizontal distance.In the former,the theoretical bound and approximate results of the success probability of users served by ground base stations and UAVs;and in the latter,this thesis proposes a division region-based user association scheme and analyzes the association probabilities and serving distance distributions of users located in different regions,and further gives the approximate results of the success probabilities of users.The results show that compared with the scenario without interference management,the proposed strategy can effectively suppress the mutual interference between UAV communication and ground cellular communication in these two cases.In conclusion,the results of this thesis provide valuable theoretical guidance for the interference management of heterogeneous cellular networks.