Research On Handover Management Of Satellite Base Station Based On 5G In Satellite-Terrestrial Integrated Networks

With the improvement of satellite communication technology and 5G technology,building a Satellite-Terrestrial Integrated Network to extend the inter-satellite flexible networking function has become an important development direction of 6G.In the long run,the ground base station and network control functions are loaded onto the satellite,and the control of the on-board base station is realized through the master node on the satellite,which can effectively reduce the time delay,support the flexibility of inter-satellite network control,and meet the demand of diversified network applications.However,due to the spatial characteristics of the satellite network,the on-board base station will have frequent access and disconnection with the master satellite,and there are problems of frequent inter-satellite handover and load imbalance on the master satellite.Therefore,how to design and implement the handover management scheme of the satellite base station in the complex network environment is the key to the convergence and collaboration of satellite-terrestrial network.To address the above problems,this thesis studies the 5G-based handover management method for satellite base stations in the Satellite-Terrestrial Integrated Network,and the main work is as follows:1.In order to realize efficient handover management of satellite base stations,a handover management scheme for satellite base stations is designed based on 5G core network architecture.By analyzing the handover function requirements,the handover management system is divided into three functional modules,namely,satellite base station management function,base station handover management function and satellite user plane function,and the signaling messages and message formats during the handover process are designed to complete,so as to realize the satellite base station mobility control function and guarantee the seamless handover of satellite base stations and the service continuity during the handover process under the Satellite-Terrestrial Integrated Network.2.The handover decision algorithm based on link attributes is studied for the problem of frequent handover of satellite base stations and unbalanced load of master satellites caused by high dynamics of satellite networks.Firstly,the inter-satellite link signal-to-noise ratio,link residual time,and satellite idle channel number are used as handover measurement objects,and the measured parameters are quantified into handover decision attribute values;then the handover trigger judgment is performed based on the decision attribute threshold values and lag margin to improve the handover accuracy and avoid unnecessary handover;finally,based on the auction model,the handover selection algorithm is developed to transform the handover target selection problem of a satellite base station into an auction game problem to maximize the overall benefit of the handover decision attributes,so as to reduce the frequency of base station handover and achieve the master satellite load balancing.3.Based on the joint simulation platform of STK and EXata,we designed and deployed a Satellite-Terrestrial Integrated Network scenario,implemented the handover protocol of the satellite base station based on the designed handover management scheme and handover judgment strategy,and tested the performance of the whole handover scheme.The test results show that the handover management system designed in this thesis can achieve low handover processing delay,and the designed handover judgment strategy has obvious optimization effect on handover trigger frequency and main control satellite load balancing.