LAUSR

This article explores cooperative communications for drone swarms which become an essential part of space-air-ground integrated networks (SAGINs), since drones (also called unmanned aerial vehicles) have the advantage of fast and flexible deployment. However, the rapid spread of drone applications leads to a dramatic increase in the spectrum and energy demand for drone communications, resulting in a shortage of spectrum and energy resources. Moreover, the inherent broadcast nature of radio propagation makes the air interface of drone communications extremely vulnerable to jamming and eavesdropping attacks, especially considering the fact that an unknown drone may sneak into a swarm for the purpose of intentionally interfering with or tapping confidential transmissions of the legitimate drones. As a consequence, a cooperative networking architecture is proposed for drone-swarm-aided SAGINs. A heterogeneous spectrum sharing mechanism is presented for drone communications to alleviate the spectrum shortage by dynamically identifying and accessing idle spectrum resources with the aid of spectrum sensing and inference. Physical-layer security is also examined for cooperative drone communications with limited energy supply. Finally, a wide range of potential applications of drone communications are pointed out, including emergency wireless networks, beyond 5G and 6G systems, and smart grid.