Low Earth Orbit (LEO) satellite networks are increasingly adopting laser (Free Space Optics, FSO) links to provide high-capacity communications. Although laser inter-satellite links offer high throughput and low latency, RF up- and downlinks remain necessary to maintain connectivity during optical outages caused by adverse atmospheric conditions. In such hybrid link scenarios, satellite buffer design remains a key challenge, since up- and downlink traffic must be buffered and forwarded among satellite nodes. The hybrid RF/FSO scenario requires careful transmission scheduling, especially at envisioned optical transmission rates of 100Gb/s and beyond, making buffer sizing critical under strict onboard energy and weight constraints. Thus, this paper analyzes throughput performance and buffer sizing in hybrid RF/laser satellite networks with finite buffer capacity, interference-aware scheduling, and weather-dependent laser link outage probabilities. Numerical results indicate that laser communications bring significant performance gains. Instead of increasing the transmission power of the satellite to maximize the throughput, we can select a suitable transmission scheduling priority to achieve a maximum throughput, while minimizing the buffer requirement, and lowering packet loss probability under realistic operational conditions and constraints.

翻译：低地球轨道卫星网络正越来越多地采用激光（自由空间光，FSO）链路以实现高容量通信。尽管激光星间链路能够提供高吞吐量和低延迟，但在大气恶劣条件导致光学中断期间，射频的上行和下行链路仍对维持连接至关重要。在这种混合链路场景下，卫星缓存设计仍是一项关键挑战，因为上行和下行链路流量必须在卫星节点间进行缓冲和转发。混合射频/自由空间光（RF/FSO）场景需要精密的传输调度，特别是在预设的光学传输速率达到100Gb/s及以上时，这使得在严格的星载能量与重量约束下，缓存容量设计变得至关重要。因此，本文分析了在有限缓存容量、干扰感知调度以及天气相关激光链路中断概率条件下的混合射频/激光卫星网络的吞吐性能与缓存容量设计。数值结果表明，激光通信带来了显著的性能增益。我们无需通过增加卫星发射功率来最大化吞吐量，而是可以选择合适的传输调度优先级，在实现最大吞吐量的同时，最小化缓存需求，并降低在实际运行条件与约束下的丢包概率。