Terahertz band (0.1-10 THz) communications is one of the candidates for 6G systems due to intrinsic massive bandwidth and data rate support. Having demonstrated the significant potential of THz band at various atmospheric altitudes, in this article, we discuss the prospects of THz communications for drone networks, more specifically, for Drone Sensor Networks (DSNs). For 6G non-terrestrial communication scenarios, drones will not only serve as on-demand base-stations, as supporting alternatives or backhauls for the terrestrial base stations, but they will also provide seamless connectivity for distributed monitoring and surveillance applications, which require an ultra-reliable low latency service for carrying multimedia data. THz band sensing will also provide additional sensing capabilities from the sky to THz-enabled DSNs. Presenting this vision, in this paper, we first discuss possible use cases of THz-enabled drone networks considering communication, sensing and localization aspects. Then, for revealing the capacity potential of THz-enabled drone networks, we provide motivating channel capacity results for communication of drones at different altitudes, under ideal channel conditions with no fading and realistic channel with beam misalignment and multipath fading. We further present major challenges pertaining to employing the THz band for DSNs, addressing physical layer issues, followed with spectrum and interference management, medium access control and higher layers and security, while reviewing some prominent solutions. Finally, we highlight future research directions with Artificial Intelligence (AI)/Machine Learning (ML)-based approaches and mobile edge computing.
Terahertz band communications as a new frontier for drone networks