全球覆盖低轨卫星星座优化设计研究

Optimization of Global Coverage LEO Satellite Constellation Design

为了在满足全球覆盖条件下使用最少的低轨卫星个数构建星座并且维持星座长期稳定性,需要寻找最优的最小地面仰角参数以此来确定轨道高度、卫星个数等星座参数,并且需要解决卫星光照不固定和轨道参数不稳定的问题。针对如何确定最小地面仰角参数的问题,通过分析星地链路衰减、最小地面仰角和轨道高度之间的相互影响关系,提出了一种已知星地链路裕量时确定卫星轨道高度和最小地面仰角的方法,能够在满足星地链路裕量的前提下获得最优的最小仰角参数;针对卫星光照不固定和轨道参数不稳定的问题,提出了一种考虑轨道特征的低轨(LEO)卫星星座设计方法。上述方法将太阳同步冻结轨道与近极轨道覆盖带(SOC)星座设计方法相结合,设计出连续全球覆盖的LEO星座。仿真结果表明,利用这上述方法设计的LEO星座能够实现连续全球覆盖,并且能够保证卫星固定的光照条件和轨道的长期稳定性。

In order to use minimum number of satellites to construct constellation and keep the long-term orbital stability on the condition of global coverage, optimum ground elevation is needed to determine altitude and constella- tion size, and the problems of unstable sunlight and orbital parameters are also to be handled. Concerning about the former problem, by analyzing the relationship among orbital altitude, satellite link attenuation and minimum ground elevation, a method that can determine the value of orbital altitude and minimum ground elevation is proposed on the condition of given satellite link margin. As to the latter problem, a low earth orbit constellation design method was proposed considering the orbital characteristics. Combining the sun-synchronous frozen orbit with near polar streets of coverage constellation design, LEO constellations that can provide continuous global coverage were designed. Simula- tion results verify that the resultant constellations can achieve continuous global coverage on the condition of constant sunlight and long-term orbital stability.