Research On 5G System Interference Coordination Technology

The deployment of small cells in dynamic time division(TDD)using orthogonal frequency division multiple access(OFDMA)is one of the key technologies of 5th-gneration(5G)mobile communication networks.Dynamic TDD is a new technology,which adapts to the asymmetry of downlink and uplink communication and makes full use of spectrum resources.However,its sufficient and flexible characteristics also result in a more complex interference environment,i.e.interference Mitigation and Traffic Adaption(IMTA)problems,and how to solve the interference problem has become a research hotspot in 5G dynamic TDD network.Firstly,we propose a new clustering scheme considering both base station interference and user interference.Cell cluster is a widely accepted approach to solve IMTA problem.However,the previous work only takes the coupling loss between base stations as the criterion of clustering scheme,ignoring the interference between user equipments.In this paper,cells subject to severe interference between base stations and between users are dynamically allocated into clusters according to the new clustering criteria.Therefore,this method can solve the problem of cross-interference between uplink and downlink at the same time to improve the uplink and downlink performance of the system.System-level simulation results show that,compared with the traditional clustering algorithm,the new clustering scheme has certain performance improvement in the downlink throughput of the system,especially in the case of severe interference with a throughput gain of 43.2% in downlink.Secondly,we study the optimal maximum cluster problem in dynamic TDD.Considering the cross-interference and co-direction interference in dynamic TDD,the method of combining clustering algorithm and power control is adopted to suppress cross-interference and co-direction interference respectively,and the optimal maximum cluster in different indoor coverage scenes is studied.We study the influences of different cell distributions and co-direction interference on the optimal maximum cluster size.In this cluster size,the cross-interference can be satisfied,the co-direction interference is not too serious,and the flexibility of dynamic TDD will not be lost.Simulation results show that the optimal maximum cluster size has practical significance in the actual indoor coverage scenes.Compared with the clustering scheme which does not limit the cluster size and the heuristic algorithm which limits the cluster size to three,both uplink and downlink throughput have significant gains.