KAUST Researchers Turn to Tethered UAVs to Boost 4G, 5G Cellular Network Coverage, Capacity

Researchers at the King Abdullah University of Science and Technology (KAUST) have published a pair of papers on tethered uncrewed aerial vehicles (TUAVS), suggesting that they could provide a solution for extending cellular network coverage by acting as flying base stations.

"Our aim has been to show that TUAVs offer a very appealing solution as a bridge between fixed base stations and free-flying drones," explains Mohamed-Slim Alouini, co-author on both papers, of his team's studies. "We hope our theoretical investigation will spur others to develop the idea to its full potential."

Dubbed "cells on wings," or COWS, the idea of placing base station hardware on a UAV and quickly deploying it in the face of network outages or disasters is not new — but Alouini and his team have been concentrating on a less-common variant, the TUAV. Where a traditional UAV is limited by its battery life, a TUAV is wired to a ground station — and a fiber-optic backhaul connection can be carried alongside its power.

The researchers looked at two key issues with TUAV deployment for network coverage: Finding the ideal position, based on an exhaustive search optimization followed by a faster but less-accurate closed-form expression approach; and how the TUAVs can enhance both coverage and capacity of cellular networks.

"An interesting result was that with longer tethers, TUAVs will outperform free-flying UAVs in just about every scenario," claims co-author Mustafa A. Kishk. "Tomorrow’s 5G equipment is heavier and consumes more power than 4G today, so their advantage will become more apparent."

The KAUST researchers aren't the only ones looking to UAVs for network expansion, though: AT&T deployed UAVs with radio equipment to provide coverage following Hurricane Maria's landfall in Puerto Rico, while Google parent Alphabet is presently rolling out an aerial network solution based on autonomous balloons.

The team's first paper has been published in the journal IEEE Transactions on Communications under closed-access terms, with a copy available in PDF format via KAUST; the second is available as a preprint on arXiv.org.