Research On Interference Coordination Strategy In LTE-Advanced Heterogeneous Networks

In recent years,the rapidly expanding mobile Internet market has put forward higher require for communication speed and bandwidth.With the rapid growth of wireless data traffic,the third generation partnership project have introduced heterogeneous networks in the long term evolution-advance(LTE-A)to meet user`s demand for mobile networks with higher speed,lower delay,high-speed mobility and other aspects.However,due to the differences in transmission power and performance between various types of base station nodes,dense co-frequency deployment will lead to network unbalance load and more complex interference.This thesis focuses on the research of the interference coordination strategy in LTE-A heterogeneous networks.The main research content of the thesis can be summarized as the following two points:For the interference problem of users in the extended area of the micro cell,the current interference coordination schemes based on time domain only configure almost blank subframes(ABS)or low power almost blank subframes(LP-ABS)for the macro base station,do no combine the two protection subframes for unified configuration.In this thesis,the inter-cell interference coordination scheme based on time domain under the micro-macro co-frequency deployment is studied.Aiming at the cross-layer interference received by users in the extended area,the enhanced inter-cell interference coordination technology is optimized and an interference coordination scheme based on the hybird protection subframes is proposed.Firstly,ABS and LP-ABS are configured for the macro base station,and users with different performances are scheduled to different subframes.Secondly,a joint base station resource allocation,hybrid protection subframe density,hybrid protection subframe ratio and user access of logarithmic utility objective function is constructed,and the complex optimization problem is decomposed into four independent sub-optimization problems for solution.The simulation results show that the proposed interference coordination scheme can effectively improve the performance of users in extended areas,and also significantly improve user fairness and load balancing.In the research of interference coordination based on frequency domain,it is found that the existing algorithms do not coordinate the interference of users at the edge of heterogeneous networks.Therefore,a resource allocation and power control strategy for user partitioning is proposed.Firstly,the users are divided into three categories based on the user's signal to interference and noise ratio.At the same time,the macro-cell layer and the micro-cell layer respectively divide into the producted band to protect the severely interfered edge users in the other layer.Finally,two independent dynamic power control strategies are adopted to ensure the service quality of center user while reducing the transmitting power of the base station on the protecrted band.The simulation results show that the proposed strategy can significantly increase the rate of macrocell edge users and microcell edge users,and can improve the performance of the entire system.