Multi-Objective Optimization Design Of LEO Satellite Constellations For Communication

With the advent of global personal communications and the rapid development of small satellite technology,low earth orbit satellite communication system has received the attention of the countries all over the world.Constellation design is the key to build low-orbit satellite communication system.Satellite constellation design for communication is a multi-objective and multi-constrained optimization problem,which is to find a constellation scheme which satisfies the task objectives under various constraints.In this paper,the design of communication satellite constellation covering the China and latitudinal zones is taken as the main content,and the optimization design method of the communication satellite constellation is explored.In chapter 1,the background of satellite constellation design is introduced,the development status of satellite communication system and satellite constellation design are summarized.The main work and contents of this dissertation is outlined.In chapter 2,aiming at the constellation design of satellite communication network under the condition of multi-constrains,the methods of constellation design are divided into optimization model and evolutionary algorithms.Firstly,a general optimization model for the constellation design of satellite communication network is proposed and the methods of setting up the optimization variables,objective functions and constraint conditions from four aspects that are constellation model,coverage performance,inter-satellite links and the cost of system are introduced.Then two multi-objective algorithms in satellite constellation design are introduced.In chapter 3,for the regional coverage satellite constellation design optimization under the condition of multi-constrains,4+2N constellation model which expands the solution space of Walker and Flower constellation models is proposed.Based on the proposed constellation model,the design goals are the orbital semi-major axis minimization and the percentage of coverage time maximization with NSGA-II to solve.The results show the satellite constellation obtained by 4+2N constellation model is better for regional constellation design.In chapter 4,for the latitude coverage satellite constellation design optimization with the inter-satellite link,the inter-satellite link requirements are introduced into constellation design.A multi-objective optimization model with the orbital semi-major axis minimization,the percentage of coverage time maximization and the number of inter-satellite links maximization is built.The relationship between the orbital semi-major axis,the constellation coverage and the number of inter-satellite links are compared and analyzed based on Walker constellation model.The results show that the number of inter-satellite links have little effect on the relationship between the orbital semi-major axis and the coverage of the constellation.As the number of satellitesincreases,the coverage of the constellation is larger and more inter-satellite links can be built.In chapter 5,the dissertation is summarized.Problems in satellite constellation design are pointed out and future research directions are forecasted.