Survey on HA2G and A2A channel measurement and modeling for airborne maneuvering networks

Airborne Maneuvering Networks (AMNs), composed of Near-Space Maneuvering Platforms (NS-MPs), High-Altitude Long-Endurance UAVs (HALE-UAVs), and Low-Altitude Maneuvering UAVs (LA-UAVs), are envisioned as a promising solution for meeting the wide-area seamless coverage requirement of the emerging sixth-generation mobile communication systems. The unique operational environment and scenarios for AMNs necessitate channel models for evaluating the communication links within them. However, the intrinsic characteristics of AMN channels, particularly High-Altitude Air-to-Ground (HA2G) and Air-to-Air (A2A) links, still present gaps in understanding, with emerging propagation models lacking a comprehensive investigation. This article provides a comprehensive survey on HA2G and A2A channel measurement campaigns across diverse AMN scenarios and reviews the state of the art in channel modeling. Key challenges in characterizing AMN channels are discussed, and future research directions are outlined to advance robust channel models for AMN communications.