Research On Self-Organizing Network Techniques In LTE System

3 GPP LTE is the latest standard for the next generation of mobile communication networks, which has made great improvement on the system architecture and radio access technologies. Self-organizing network (SON) technology is one of the most important aspects in LTE systems. Next generation mobile networks will be self-configured, self-optimized and self-healed. SON technologies can reduce operational and capital expenditure by diminishing human involvement in network operational tasks. SON technology in LTE system has attracted much attention from both industry and academia, and is still far from being explored.This thesis introduces the mobility robustness use case of SON, and develops mobility robustness optimization (MRO) algorithms under both the RRC connected and idle mode. The simulation results show that the algorithms improve the system performance significantly. The main contribution is as follows:Firstly, introduce LTE system architecture and SON technology. Discuss the progress of 3GPP LTE standardization and the challenges faced by SON.Secondly, introduce hard handover in LTE and the mobility robustness optimization use case in MRO for user equipments (UEs) under RRC connected mode. Based on the mobility status of UE, a novel algorithm is proposed, which assigns different handover hysteresis parameters for UEs at different speeds. The simulation results show that the algorithm greatly increases the handover success rate and improves the user experience.Thirdly, introduce cell selection and cell reselection procedures for UEs under RRC idle mode. Due to the impact of the mobility load balancing procedure on handover parameters which makes handover parameters and cell selection/reselection parameters unmatched, we consider a negotiation procedure between cells in the process of optimizing cell selection/reselection parameters. The simulation results show that the negotiation procedure helps to balance the cell load, decrease the number of ping-pong handovers, and hence improve system performance.