Research Of Mobility Management In LTE-A Small Cell System

In order to meet the transport demand of mobile data traffic whicn has explosive growth in recent years, small cell is widely used in LTE-A(Long Term Evolution-Advanded) system. Small cell faces many problems which are needed to be solved although it is considered to be the most potential solutions to improve system capacity and expand the coverage. The mobility management issues is outstanding and has become the focus of the industry. This artical focuses on the evaluation and optimization of user mobility performance in outdoor macro with pico cell overlapping coverage scenario and indoor pure small cell coverage scenario, based on tracking the progress of small cell standardization work. The main work is as follows:1.Small cell is fully introduced and the system level simulation platform is constructed. According to the 3GPP(Third Generation Partnership Project) related technical report, key technologies of LTE-A small cell simulation system are studied and two dynamic system level simulation platform based on event driven are set up.2.The performance evaluation of basic handover algorithm is carried out on the two system level simulation platform. Simulation results show that outdoor macro with pico cell overlapping coverage scenario has greater mobility problems and mobility problems of indoor pure small cell coverage scenario are small.3.Mobility optimization design is conducted in the outdoor macro with pico cell overlapping coverage scenario. Firstly, this thesis proposes a scheme which is expected to reduce handover failure rate through reducing the transmission failure of handover command and verification work is conducted on the former system simulation platform.The simulation results show that the main cause of the handover failure is too late handover which leads to the trigger of RLF(Radio Link Failure). Finally, analysis of mobility enhancement on dual connectivity technique is analyzed. Dual connectivity is currently researched by 3GPP. The simulation results certificate that dual connectivity can effectively enhance the user mobile performance.The simulation platform which are set up by this thesis is the foundation of the subsequent research. Performance evaluation work provides basis of the standardization ofthe small cell. The study of mobility performance optimization has important pratical reference significance in solving the mobility management problems of small cell.