Downlink Coordinated Multiple Point Transmission In Wireless Fractal Cellular Network

Coordinated Multiple Point(Co MP)transmission is one of the key techniques and research focus in the mobile communication networks in recent years.Many studies have shown that Co MP as a technology which can improve data rate,spectrum efficiency,and edge user throughput,will be widely used in 5G(Fifth Generation)networks.In Co MP,the selection of cooperative base station is the first step so as the most critical step,which is affected by coverage boundary of the wireless fractal network to a certain degree.Therefore,in this paper,we focus on the cooperative base station selection method in the downlink wireless fractal cellular network,and discuss the overall network performance under different methods.In this paper,we first study several basic models of existing Co MP,analyze different types of Co MP in principle,and discuss the performance gains of different types from the perspective of average cell user throughput and cell edge user throughput.Studies have shown that Co MP shows significant performance advantages over non-Co MP transmission whether in homogeneous or in heterogeneous networks.Among these Co MP types,JT(Joint Transmission)Co MP shows better performance than others,so the research in the following part are based on JT Co MP model.In view of the fractal characteristics of coverage boundary in wireless fractal cellular networks,we establishe an anisotropic path loss model.Then we use stochastic geometry theory to model the Small-Cell base station and user distribution,and establish the downlink JT Co MP network model.Considering two common cooperative base station selection strategies,we derive the user achievable rates and network energy efficiency under these two strategies,and make simulation analysis and comparison of network performances.The results show that the RSS(Received Signal Strength)-based strategy can enable users to obtain higher achievable rates.Finally,based on the capacity challenge faced by existing backhaul networks and the problem of limited base station resources,we propose a new downlink JT Co MP clustering algorithm.The proposed base station clustering algorithm can solve the problem of how to make the total backhaul traffic smaller when the number of base station resource blocks is limited and the minimum rate requirement of each user in the network can be guaranteed.The simulation results show that the proposed algorithm can decrease the total backhaul traffic in the network under the existing system constraints.