A low earth orbit (LEO) constellation can support broadband Internet access and can also be a platform for navigation augmentation for global navigation satellite systems. LEO satellites have the potential to transmit very strong navigation signals; they also show rapid changes in spatial geometry as they come closer to earth and travel faster over stations than satellites in medium or high orbits do. Before the establishment of a LEO-based navigation augmentation system, constellation design is a critical task. Previous LEO constellations have usually employed single polar or near-polar orbits for global coverage, resulting in fewer visible satellites at low latitudes. We propose and optimize several hybrid LEO-augmented constellations using a genetic algorithm to realize globally even coverage. When there are 100 LEO satellites, the average numbers of visible satellites during a regression period are 5.49, 5.44 and 5.47, with standard deviations of 0.44, 0.18 and 0.28, for the optimized hybrid polar-orbit/Walker, orthogonal circular-orbit/Walker and Walker/Walker constellations, respectively. For the hybrid orthogonal circular-orbit/Walker constellation type, the necessary numbers of LEO satellites to realize globally even coverage with six visible satellites are 109, 172 and 221 for elevation mask angles of 7°, 15° and 20°, respectively. For coverages with four and five visible satellites with an elevation mask angle of 7°, the required numbers of satellites are 90 and 93, respectively. All proposed hybrid constellations can provide 100% global coverage availability with one to three visible satellites for broadband Internet access.

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基于遗传算法的基于LEO的导航增强系统混合星座设计

低地球轨道（LEO）星座既可以支持宽带Internet接入，又可以成为全球导航卫星系统的导航增强平台。LEO卫星有可能发射非常强的导航信号。它们比中或高轨道的卫星更靠近地球，并在站上传播得更快，因此它们的空间几何结构也发生了快速变化。在建立基于LEO的导航增强系统之前，星座图设计是一项关键任务。先前的LEO星座通常采用单极或近极轨道进行全球覆盖，从而导致低纬度地区的可见卫星更少。我们提出并使用遗传算法优化几个混合LEO增强星座，以实现全球平均覆盖。当有100颗LEO卫星时，对于优化的混合极轨/沃克，正交圆轨道/沃克和沃克/沃克星座，回归期内可见卫星的平均数量分别为5.49、5.44和5.47，标准差分别为0.44、0.18和0.28。 。对于混合正交圆轨道/沃克星座类型，对于7°，15°和20°的仰角，要用六个可见卫星实现全球平均覆盖的LEO卫星分别为109、172和221。对于具有7°仰角遮罩角的四颗和五颗可见卫星的覆盖范围，所需的卫星数量分别为90和93。所有建议的混合星座都可以提供100％的全球覆盖可用性，其中包括一到三颗可见卫星，用于宽带Internet访问。