Research On User-centric Virtual Cell Technology In Ultra-Dense Network

5G expects to realize the ultra-high data transmission traffic density in the hot high-capacity area to meet the demand of users’ network traffic.Ultra-dense network(UDN)deploying a large number of low-power transmit points(TP)in hot areas is an effective way to rapidly increase user rates.However,as the TP density increases in ultra-dense network,the area of cell coverage overlaps,inter-cell interference gradually increases,and network performance decreases.Serving for centric user with several TPs and coverage around the user,user-centric virtual cell technology can solve the inter-cell interference in the ultra-dense network.In this paper,user-centric virtual cell technology in ultra-dense network will be studied to suppress inter-virtual cell interference.The specific research contents are as follows:Aiming at the problem of user-centric virtual cells overlapped and bringing in interference in ultra-dense network,this paper proposes virtual cell interference suppression scheme based on overlapped merging and beamforming.In the merging phase,the overlapped ratio is introduced,and the virtual cell cluster is formed according to the overlapped ratio.In the beamforming phase,it solves the beamforming problem to maximize the system user rate.Simulation results show that the proposed scheme can effectively reduce interference and improve system throughput.Aiming at the serious overhead of the centralized beamforming design of virtual cells in the above ultra-dense network,this paper continues to propose a low overhead transmission scheme of virtual cell based on hierarchical beamforming.The interference in ultra-dense network will be layered,and TPs in virtual cell cluster will share perfect channel state information to eliminate more serious multi-user interference.Large-scale channel state information is shared between virtual cell clusters to further suppress inter-cluster interference and improve system throughput.The simulation results show that this low overhead transmission scheme can reduce the channel overhead and guarantee the system user rate increase.