Research On Energy-efficient User Access And Cell Handover Algorithm For Ultra-dense Networks

With the rapid development of global information technology,mobile data traffic is exploding.Ultra-Dense Network(UDN)refers to an effective way to increase system capacity in 5G net,works[1].And Energy efficiency optimization has become a key issue in ultra-dense networks,taking into account economic,operational and environmental impacts[2].User access and user mobility management schemes are key technologies for improving energy efficiency in ultra-dense networks.However,due to the diversity of user requests time and space,the user's traffic demand and location are actually uncertain.Therefore,new requirements are imposed on traditional user access and mobility management solutions.This thesis comes from the enterprise cooperation project《The Research on the New Generation Network Key Technology and Business Analysis Technology》.The thesis studies the user access problem in the case of bandwidth inconsistency in ultra-dense networks and the user mobility management problem in dynamic network environment.The optimal access algorithm and cell handover algorithm are obtained by solving the robust optimization problem.The main research contents of this thesis:1.The current status of energy efficiency optimization of ultra-dense networks is studied.The existing energy efficiency optimization technologies are classified,and the main problems of current energy efficiency optimization are listed.The current research status of existing ultra-dense network user access technologies and cell handover technologies is presented.Summarized and analyzed.2.An energy-efficient user access algorithm based on robust optimization is proposed aiming at the problem that the user bandwidth requirement in the ultra-dense network is uncertain and affects the feasibility and stability of the user access strategy.Firstly,the Soyster robust model is established,and then the user access matrix is optimized under the condition that the user bandwidth is uncertain.The simulation results show that the algorithm can maintain the reliability of access within a certain range of bandwidth requirements and improve the stability of access.3.An efficient energy-efficient cell handover algorithm based on robust optimization is proposed aiming at the problem of frequent handover and high handover failure rate caused by the increase of base station density in ultra-dense networks.The Bertsimas&Sim robust model is established,and then the user handover matrix is optimized to solve the dynamic change of the user's position.The simulation results show that the algorithm can maintain the accessibility within a certain range of motion and improve the stability of the system.