Research On Performance Optimization Of Ultra-Dense Cellular Backhaul Networks

With the use of massive multi-input multiple-output(MIMO)and millimeter-wave communication technology,the future cellular network needs to deploy a large number of small cells to ensure the seamless coverage of mobile users.Thus ultra-dense cellular networks are becoming an inevitable trend.For the sake of the intensive base station(BS)deployment,the traditional wired fiber backhaul has been unable to meet the requirements of mobile network in terms of economy and scalability,so the wireless backhaul of ultra-dense cellular networks has become a research hotspot.In this paper,we study the networking of 5G ultra-dense cellular networks and discuss the saturation points of ultra-dense cellular networks from the perspective of wireless backhaul capacity and energy efficiency.The results show that there are upper capacity limits associated with the density of small cell.As a consequence,we conclude that the 5G ultra-dense cellular network is a density-limited communication system.In order to improve the wireless backhaul link capacity,the potential for employing millimeter-wave in backhaul networks is studied.Considering the short transmission range of millimeter wave,the connected cluster model of ultra-dense cellular network is studied and its connectivity is analyzed.Analysis and simulation indicate that the connectivity probability of small cell cellular network within a macro base station coverage approaches 1 when the density of small cell base station is large enough.Finally,this thesis establishes and derives the capacity model of the millimeter-wave backhaul network.Unlike most existing works of backhaul network,this paper considers the impact of backhaul gateway deployment on the cost of backhaul networks.Then taking the deployment of backhaul gateway into consideration,a cost efficiency model of millimeter-wave backhaul network is derived.Based on the cost-efficiency model,a two-scale optimization solution to maximize the cost efficiency of 5G wireless backhaul networks is proposed.Specifically,the number and positions of gateways are optimized in the long time scale of 5G wireless backhaul networks.The wireless backhaul routings are optimized in the short time scale of 5G wireless backhaul networks.The simulation results show that the rational deployment of the gateway(including the number and locations)and appropriate wireless backhaul routing can significantly improve the cost efficiency of 5G backhaul network.