The rapid expansion of latency-sensitive applications has sparked renewed interest in deploying edge computing capabilities aboard satellite constellations, aiming to achieve truly global and seamless service coverage. On one hand, it is essential to allocate the limited onboard computational and communication resources efficiently to serve geographically distributed users. On the other hand, the dynamic nature of satellite orbits necessitates effective service migration strategies to maintain service continuity and quality as the coverage areas of satellites evolve. We formulate this problem as a spatio-temporal Markov decision process, where satellites, ground users, and flight users are modeled as nodes in a time-varying graph. The node features incorporate queuing dynamics to characterize packet loss probabilities. To solve this problem, we propose a Graph-Aware Temporal Encoder (GATE) that jointly models spatial correlations and temporal dynamics. GATE uses a two-layer graph convolutional network to extract inter-satellite and user dependencies and a temporal convolutional network to capture their short-term evolution, producing unified spatio-temporal representations. The resulting spatial-temporal representations are passed into a Hybrid Proximal Policy Optimization (HPPO) framework. This framework features a multi-head actor that outputs both discrete service migration decisions and continuous resource allocation ratios, along with a critic for value estimation. We conduct extensive simulations involving both persistent and intermittent users distributed across real-world population centers.
翻译:延迟敏感型应用的快速扩张,重新激发了在卫星星座上部署边缘计算能力的研究兴趣,旨在实现真正全球无缝的服务覆盖。一方面,必须高效分配有限的星上计算与通信资源,以服务地理分布的用户。另一方面,卫星轨道的动态特性要求有效的服务迁移策略,以在卫星覆盖区域变化时维持服务连续性与质量。我们将该问题建模为一个时空马尔可夫决策过程,其中卫星、地面用户和飞行用户被建模为时变图中的节点。节点特征包含排队动态以表征丢包概率。为解决此问题,我们提出了一种图感知时序编码器(GATE),联合建模空间相关性与时序动态。GATE使用双层图卷积网络提取卫星间及用户间的依赖关系,并使用时序卷积网络捕获其短期演化,生成统一的时空表征。所得的时空表征被输入混合近端策略优化(HPPO)框架。该框架采用多头行动器,同时输出离散的服务迁移决策和连续的资源分配比例,并配备评估器进行价值估计。我们开展了广泛仿真,涉及分布于全球真实人口中心的持续性与间歇性用户。