Design And Implementation On Virtual Cell-Based Mobility Enhancement Technology In User-Centric Networks

The concept of 5G design has experienced the Shannon’s theory rethinks,the cellular concept rethinks,the signaling control rethinks,to the protocol rethinks.Based on those concepts,user-centric network(UCN)is specifically identified as the basis for a 5G system solution.UCN provides a unified wireless access architecture with a public high-level protocol through the architecture and function redefinition of radio access network(RAN).UCN RAN will break through the traditional cellular border and achieve local mobility robustness enhancement through the coordination among access points and the deployment of edge data center and controller.Ultra-dense network(UDN)will be an effective solution for 1000 times data rate in future network by deploying dense small cells for spatial reuse increase.However,the smaller coverage of small cells will cause more physical edges,thus leading to more frequent handovers and severe interference.This paper proposes a novel mobility enhancement scheme in 5G UCN RAN based on cell virtualization to decrease the handover failure rate.The main works are as follows:Firstly,this paper introduces the handover technology in communication system and studies cell virtualization as well as the uplink and downlink reference signals based on CoMP.Based on the analysis of handover problems in UDN,this paper introduces the UCN architecture under which the user-specific virtual cell is built,and designs two types of virtual cells which are centralized and distributed.Secondly,this paper analizes the mobility problems in the process of handover process and proposes the mobility enhancement scheme based on virtual cell,including the cell identification design,the measurement design and the handover procedures design as well as performing the simulation to verify the gains of virtual cell in UCN.Furthermore,the dynamic virtual cell is studied which is formed based on prediction of moving trajectory,to decrease the unnecessary handovers and improves the hit rate.Finally,the user plane of multi-connectivity is designed based on the RRC-diversity to study and analyse the mobility robustness as well as throughput gains in multi-connectivity scenary.