Space-air-ground integrated network (SAGIN) in disaster management: A Survey

Large-scale natural disasters or public security incidents frequently cause substantial damage to both human life and property, as well as terrestrial communication infrastructure. As a result, this disruption often cuts off communication, leaving the victims isolated from the outside world. Timely completion of Search and Rescue (SAR) operations within the first 72 hours following a disaster is of critical importance, as it can significantly protect human lives and reduce property damage. Note that conducting SAR operations in post-disaster areas requires not only communication support but also computing support. In light of this, it is particularly important to rapidly establish an emergency communication system with computing resources, which offers high reliability, low latency, and high capacity. Such a system is crucial for reducing the threat posed by disasters to human lives. Given the challenges in rapidly restoring terrestrial networks, flexible aerial networks and existing satellite networks emerge as optimal candidates for emergency communications. Meanwhile, the integration of aerial platforms, such as High Altitude Platforms (HAPs) and Low Altitude Platforms (LAPs), can effectively reduce the transmission latency associated with satellite networks and alleviate capacity constraints in terrestrial emergency communication networks. The Space-Air-Ground Integrated Network (SAGIN)-based emergency communication system can utilize the advantages of each segment, including the extensive coverage provided by the space network, the flexibility of the air network, and the high transmission data rates and low latency of the ground network. Consequently, this represents an exemplary paradigm for supporting SAR operations in the future. In this paper, we provide a comprehensive survey of SAGIN-based emergency communication systems, identify key challenges, and discuss promising technologies. Furthermore, future research directions are outlined from multiple perspectives.