Free space optical (FSO) communication refers to the information transmission technology based on the propagation of optical signals in space. FSO communication requires that the transmitter and receiver directly see each other. High-altitude platforms (HAPs) have been proposed for carrying FSO transceivers in the stratosphere. A multihop HAP network with FSO links can relay traffic between ground FSO nodes. In this study, we propose an end-to-end switching model for forwarding traffic between massive pairs of ground FSO nodes over a HAP network. A protection mechanism is employed for improving the communication survivability in the presence of clouds, which may break the line of sight (LoS) between HAPs and ground nodes. We propose an algorithm to identify a set of necessary HAPs and to design the HAP network topology in integrating the protection mechanism. The design aims to a network with the minimal equipment cost. The results demonstrate that, even though networks with survivable capacity use more resources, they are not necessary much more expensive than those without survivability in terms of equipment, i.e., HAPs and FSO devices, and in terms of wavelength resource utilization.

自由空间光通信（FSO）是指基于光信号在空间中传播的信息传输技术。FSO 通信要求发射器和接收器直接看到对方。已经提出高空平台 (HAP) 用于在平流层中携带 FSO 收发器。具有 FSO 链路的多跳 HAP 网络可以在地面 FSO 节点之间中继流量。在这项研究中，我们提出了一种端到端交换模型，用于通过 HAP 网络在大量地面 FSO 节点对之间转发流量。采用保护机制来提高存在云时的通信生存能力，这可能会破坏 HAP 和地面节点之间的视线 (LoS)。我们提出了一种算法来识别一组必要的 HAP，并在集成保护机制的过程中设计 HAP 网络拓扑。该设计旨在以最低的设备成本建立网络。结果表明，即使具有可生存能力的网络使用更多资源，但在设备（即 HAP 和 FSO 设备）以及波长资源利用方面，它们并没有必要比没有可生存能力的网络贵太多。