What Will the Future of UAV Cellular Communications Be? A Flight From 5G to 6G

Abstract

What will the future of UAV cellular communications be? In this tutorial article, we address such a compelling yet difficult question by embarking on a journey from 5G to 6G and expounding a large number of case studies supported by original results. We start by overviewing the status quo on UAV communications from an industrial standpoint, providing fresh updates from the 3GPP and detailing new 5G NR features in support of aerial devices. We then dissect the potential and the limitations of such features. In particular, we demonstrate how sub-6 GHz massive MIMO can successfully tackle cell selection and interference challenges, we showcase encouraging mmWave coverage evaluations in both urban and suburban/rural settings, and we examine the peculiarities of direct device-todevice communications in the sky. Moving on, we sneak a peek at next-generation UAV communications, listing some of the use cases envisioned for the 2030s. We identify the most promising 6G enablers for UAV communication, those expected to take the performance and reliability to the next level. For each of these disruptive new paradigms (non-terrestrial networks, cellfree architectures, artificial intelligence, reconfigurable intelligent surfaces, and THz communications), we gauge the prospective benefits for UAVs and discuss the main technological hurdles that stand in the way. All along, we distil our numerous findings into essential takeaways, and we identify key open problems worthy of further study.

Integrating Terrestrial and Non-terrestrial Networks: 3D Opportunities and Challenges

“…In Rel-17, 3GPP introduced a set of basic features to enable 5G NR operation over NTNs in FR1, i.e., up to 7.125 GHz. 3GPP Rel-18 TABLE I: Overview of the 3GPP standardization work on NTN and UAV communications [1], [11], [12].…”

“…We focus our analysis on the uplink, the more data-hungry direction for UAVs, whose generated transmissions may pose a threat to legacy GUEs [1]. Fig.…”

“…These largely benefit from increasing the deployment density of MNO A and employing EDA precoding. Focusing on the 95%-tile, standalone MNO T with ZF provides 36 Mbps as opposed to the 134 Mbps achievable with MNO T -plus-MNO A and ISD A = 500 m. The former may be sufficient for remote UAV controlling through HD video, whereas the latter may also empower 8K real-time video live broadcast (for future VR applications) and 4×4K AI surveillance (for control and anti-collision in building-intensive areas, lacking positioning accuracy) [1].…”

“…Its extreme heterogeneity makes realizing a 3D network a remarkable endeavor. In the sequel, we propose much-needed research towards an integrated TN-NTN [1], [7].…”

“…Life in the 2030s and beyond will look quite different from today's: hordes of network-connected UAVs (uncrewed aerial vehicles) will navigate 3D aerial highways-be it for public safety or to deliver groceries to our doorstep-, and flying taxis will reshape how we commute and, in turn, where we live and work. The bold ambition of reaching for the sky will take the data transfer capacity, latency, and reliability needs for the underpinning network to an extreme, requiring dedicated radio resources and infrastructure for aerial services [1], [2].…”