Modeling And Performance Research On Stochastic Heterogeneous Cellular Networks

Driven by the high-speed development of the mobile Internet,wireless industry is currently facing an increasing demand for mobile data traffic over cellular networks.To meet this demand,one of the solutions is the deployment of heterogeneous cellular networks(HCNs),where small cell base stations(SBSs)coexisting with the existing macro base stations(MBSs).Considering the stochastic character of small cell base stations,this thesis focus on stochastic heterogeneous cellular networks.To analyze the performance of HCNs,a feasible method is to model BS locations as random which follows a spatial stochastic point process,such as the Poison Point Process(PPP).The main contributions of this thesis are as follows.1.This thesis considers the problem of base station(BS)cooperation in the downlink of a two-tier HCNs.We achieve the following contributions.Firstly,a novel and flexible cross-tier cooperative scheme is proposed in order to enhance the performance of the system.This scheme allows BSs within each tier to cede their original cell range to cooperative region,thus extent the cooperative region,where users are better served through cross-tier cooperation.Secondly,using tools from stochastic geometry,we derive expressions for outage probability as well as average date rate of our scheme.Additionally,Simulation results are given to verify the accuracy of our analysis and numerical results indicate that our cooperative scheme reduces the outage probability by about 21.2%and increases the average data rate by about 9.2%,compared with the traditional maximum reference signal received power(RSRP)scheme.2.Through load balancing,the overall throughput of HCNs can be improved.Meanwhile,in order to offload more users from macrocell to small cell,LTE-A introduces cell range expansion(CRE).The utilization of CRE,however,brings serious macrocell interference to the expanded small cell users,especially when the expansion range is large.Aiming at this problem,we propose a joint frequency distribution and interference alignment scheme with CRE in HCNs,improving spatial multiplexing gain of the expansion users.Simulation results show that our scheme significantly enhances the capacity of users,improves system fairness and the performance of traffic offloading.