Future Skies: Optical Wireless Backhaul Networks with Multiple Airborne Layers

21 February 2024 15:00 - 16:00

Optical wireless backhaul networks utilizing multiple airborne layers offer enhanced data transfer capabilities, reduced latency, and improved connectivity in the evolving landscape of communication technologies. These networks leverage various altitudes of unmanned aerial vehicles (UAVs) or drones equipped with optical communication technology to establish efficient data links between ground stations or other aerial layers. This approach holds promise for addressing the growing demand for high-speed, reliable communication in the future.

The deployment of non-terrestrial networks (NTNs) is expected to establish comprehensive global coverage for the upcoming generations of wireless technology. Addressing the substantial portion of the global population that remains unconnected or under-connected, leveraging NTNs becomes imperative to bridge the existing digital divide. NTNs encompass a range of technologies such as High-Altitude Platform Stations (HAPSs), Satellites (GEO, MEO, LEO), and Unmanned Aerial Vehicles (UAVs). Advances in autonomous avionics and lightweight composite materials position HAPSs as viable NTN nodes for future networks, alongside rotary-wing unmanned aerial vehicles (UAVs). In the realm of advanced wireless technologies like 6G and beyond, the objective is to seamlessly integrate NTN nodes with terrestrial networks. Currently, there are isolated deployment examples, including Google Loon, Nokia F-Cell, AT&T Tethered Flying Cell on Wing (COW), LEO mega-constellations, and Turkcell-Dronecell. This presentation focuses on the design of a multi-layer airborne backhaul network, utilizing HAPSs and rotary-wing UAVs to establish free space optical (FSO) backhaul connections with ground-based stations. HAPS fleets operate in circular tracks at stratospheric altitudes. On the other hand, rotary-wing UAVs operate at medium and lower altitudes, complementing HAPSs. The airborne backhaul architecture requires careful design to ensure uninterrupted connectivity with ground-based stations, eliminating coverage gaps. The presentation outlines a systematic approach for designing FSO-based airborne backhaul systems, detailing the process of determining the appropriate number of layers, HAPS tracks, HAPS units per track, the number of UAVs at lower altitudes, the operating altitude for middle-layer UAVs, and the number of laser sources per airborne node based on a given coverage area.