天地一体化网络下的多目标切换策略

Multi-objective Handover Strategy for Space Earth Integrated Network

随着低地球轨道(Low Earth orbit,LEO)卫星的网络结构日益复杂,高效的信息传输对于天地一体化网络(Space-ground integrated network,SGIN)的发展至关重要。本文通过同时考虑切换次数、仰角和可用信道数量等指标来优化多目标切换问题。通过数学建模将地球划分为多个区域,并将优化目标定义为切换次数和负载均衡的加权和,根据不同场景确定加权系数。通过设置表示信息传输质量的阈值,可以优化仰角。本文将天地一体化网络的卫星切换问题转化为整数线性规划(Integer linear programming,ILP)问题,并使用数学工具求解,以提供最优解。同时,由于在实际工程应用中基于ILP的策略具有较高的算法复杂性,本文还提出了一种基于二分图的启发式切换策略。通过对一个实际应用的低轨卫星星座(Globalstar)进行仿真实验,验证了本文所提出的切换策略的有效性。

Efficient information transmission is crucial for the development of space-ground integrated network(SGIN),especially with the growing complexity of low Earth orbit(LEO)satellite architectures.This study aims to optimize the handover process between terrestrial users and satellites by considering metrics such as handover times,elevation angle,and available channels.The proposed mathematical model divides the Earth into multiple regions,and the optimization objective is a weighted sum of the number of handovers and load balance,which determines the weighted coefficients based on different scenarios.The elevation angle can be optimized by setting a threshold that indicates the quality of information transmission.The study transforms the SGIN handover problem into an integer linear programming(ILP)problem and solves it by using mathematical tools to provide an optimal solution.However,due to the high algorithmic complexity of the ILP-based strategy in practical engineering applications,a heuristic handover strategy based on bipartite graphs is also proposed.Simulations on a typical LEO satellite constellation(Globalstar)validate the effectiveness of the proposed handover strategies.