Space-air-ground integrated networks (SAGIN) are pivotal for achieving uninterrupted in-flight connectivity (IFC). Most existing studies, however, merely treat satellites as transparent forwarding nodes, and overlook their caching capabilities in enhancing the IFC data rate. In this paper, we consider an IFC-oriented SAGIN, where the satellites collaboratively deliver the content to airborne passengers to facilitate airborne communication. Considering the cached files instantaneously accessible via satellites, this work pioneers the integration of multiple inter-satellite links (ISLs) into the IFC framework, thereby innovating the content delivery process. To minimize the average delay of content delivery, we formulate an optimization problem and propose an exact penalty-based method to derive the satellite association scheme. Our proposed framework has a low complexity and thus paves the way for high-speed Internet connectivity to aviation passengers. Finally, simulation results are presented to demonstrate the effectiveness of our proposed IFC framework for SAGIN.

翻译：空天地一体化网络（SAGIN）对于实现不间断的空中互联（IFC）至关重要。然而，现有研究大多仅将卫星视为透明转发节点，忽视了其缓存能力对提升IFC数据速率的潜在作用。本文研究一种面向IFC的SAGIN，其中卫星通过协作方式向空中乘客分发内容以促进空中通信。考虑到通过卫星可即时访问缓存文件，本研究开创性地将多条星间链路（ISL）集成到IFC框架中，从而革新了内容分发流程。为最小化内容分发的平均时延，我们构建了一个优化问题，并提出一种基于精确罚函数的方法来推导卫星关联方案。所提框架具有较低复杂度，从而为航空乘客实现高速互联网接入铺平了道路。最后，仿真结果验证了所提SAGIN-IFC框架的有效性。