Research On The Interference Management Mechanism Under Carrier Aggregation In Heterogeneous Networks

With the rapid development of mobile Internet and large-scale influx of communication equipment,the capacity of current cellular network is far from meeting explosive growth demand for data traffic.To cope with this problem,some key technologies such as heterogeneous networks(Het Nets)and carrier aggregation(CA)have been introduced.Carrier aggregation technology flexibly expands system bandwidth by aggregating carriers to improve users' peak rate as well as spectrum utilization.Heterogeneous networks deploy low-power miniaturized base stations in the coverage hole of macro base stations or hot-spot areas to increase system capacity and provide traffic offloading.However,in order to improve the reuse of resources,heterogeneous networks adopt intra-frequency networking,which brings serious inter-cell interference,especially for the cell edge users.Besides,multi-user diversity makes the edge users with poor channel quality compete for less resources so that the performance declines in heterogeneous networks supporting carrier aggregation.Therefore,solving the interference problem is the premise to give full play to the advantages of heterogeneous networks and carrier aggregation technology.Hence,this paper focuses on the interference management of randomised heterogeneous networks supporting carrier aggregation.First,a typical Macro-Pico heterogeneous network whose Macro stations are deployed regularly is taken as a research scenario and how to combine the soft frequency reuse technology to perform interference coordination under carrier aggregation is discussed.Based on the frequency aggregation characteristics of carrier aggregation and the frequency division characteristics of soft frequency reuse,two joint schemes named global division and local division are given.The static configuration scheme of the frequency reuse mode of the joint scheme and power control factor of the multilayer network in simple scenario are analyzed.The simulation results show that both the two joint schemes can improve the performance of the edge users and system capacity.Meanwhile,The two schemes have different advantages for different types of users.When the number of users is enough,the overall performances of the system of two schemes are the same.Then,a randomised Macro-Pico heterogeneous network modeled by spatial poisson point process(PPP)is taken as a research scenario and the detailed configuration scheme of the each layers' frequency reuse mode of the joint scheme which is well applicable to the complex network scene and suppress the co-tier and cross-tier interference at the same time is studied.Based on the interference characteristics in the downlink transmission,an interference graph-based method is used for Macros and a dynamic information interface method is used for Picos to configure the frequency reuse pattern.Based on the fact that the interference suffered by Picocell-edge users is much greater than that suffered by Macrocell-center users,we exploit Coordinated Multiple Points(Co MP)transmission collaborated with soft frequency reuse to further improve the performance of edge users in Picos.At the same time,there exist different users with different aggregation capabilities because of the backward compatibility of the system.Thus,the scheduling algorithm under carrier aggregation is explored and the specific resource block(RB)allocation scheme is designed to balance the fairness of different user types.The simulations results show that our scheme can effectively improve the performance of Macrocells' and Picocells' edge users,meanwhile ensuring the fairness between different types of users from the point view of cumulative average rate as well as instantaneous average rate.