Research And Implementation Of User Handover Scheme For Low-orbit Satellite Communication System

In recent years,verification satellites of several low-orbit satellite systems have been launched into the air.The low-orbit satellite communication system has developed rapidly and is expected to become the next high-speed communication system.Low-orbit satellite communication systems are characterized by global coverage,low transmission delays,and low power requirements,and thus have a natural advantage in implementing personal mobile communication systems.Due to the high-speed movement of low-orbit satellites around the earth,user terminals need to frequently hand over to another satellite during communication.How to design the user's handover scheme between satellites is an important problem to be solved in the design of satellite communication systems.The main contents of this thesis are as follows:1.This thesis studies the architecture of the low-orbit satellite communication system,satellite selection algorithm,handover process,and handover scheme functional requirements.The characteristics of the low-orbit satellite communication system and the inter-satellite handover algorithm are analyzed and summarized,which provides the basis for the subsequent research and design work.2.For the problem of how to select the destination satellite for inter-satellite handover,a user terminal satellite selection algorithm based on multi-attribute decision making is proposed,considering the received signal strength of the terminal,the remaining satellite service time of the candidate satellite and the number of idle channels of the candidate satellite.Three attributes are combined into a multi-attribute decision problem.For the calculation of the remaining service time of candidate satellites,this thesis also proposes a method based on geometric derivation.The effectiveness of this method is verified by simulation.The effectiveness and advantages of the proposed handover algorithm are verified by comparing other handover strategies.3.This thesis designs and implements the switching of the overall module,process,and message.Firstly,the overall network structure of the low-orbit satellite communication system is introduced.The research and design focus on the problem of how the ground-based gateway controller implements the handover function.By analyzing the handover functional requirements,the functions of the ground station controller of the gateway are divided into three functional modules:the handover management module(SC),the satellite management module(Sl)and the common service module(CS).The aim of this thesis is to design and implement the functional modules and the process of handover message among the modules.