Page 13 - ITU Journal Future and evolving technologies Volume 2 (2021), Issue 7 – Terahertz communications

ITU Journal on Future and Evolving Technologies, Volume 2 (2021), Issue 7

TERAHERTZ BAND COMMUNICATIONS AS A NEW FRONTIER FOR DRONE NETWORKS

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Akhtar Saeed , Ozgur Gurbuz , Mustafa Alper Akkaş , Ahmet Ozan Bicen 3
1 Electronics Engineering Program, Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul, 34956,
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Turkey, Department of Computer Engineering, Bolu Abant Izzet Baysal University, Bolu, 14280, Turkey, Independent
Contributor
NOTE: Corresponding author: Akhtar Saeed, akhtarsaeed@sabanciuniv.edu
Abstract – 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 signi icant potential of THz band at various atmospheric alti‑
tudes, in this article, we discuss the prospects of THz communications for drone networks, more speci ically, 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 irst 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 Arti icial Intelligence (AI)/Machine Learning (ML)‑based
approaches and mobile edge computing.
Keywords – Arti icial intelligence, disaster management, drone networks, drone sensor networks, machine learning,
mobile edge computing, monitoring, surveillance, terahertz communications, terahertz sensing
1. INTRODUCTION demand network coverage from the air (Fig. 1(c)), as an
alternative as well as support to the terrestrial base sta‑
Drones will soon inhabit our skies as they are easily avail‑ tions, for communal gatherings, concerts etc. Such drone
able, reliable and low‑cost devices. The demand for such base stations can also be useful in disaster‑struck areas,
hovering drones is increasingly witnessed in civil and go‑ where the terrestrial communication infrastructure is
vernment applications, as globally, many governments damaged. Nevertheless, in each of the above‑mentioned
and industries have been investing heavily in deploying possible real‑world applications, frequent mobility of the
drone networks as per their requirements [1]. drones with constrained energy resources will be re‑
Typically, small drones with multi‑copter‑like quired to be addressed to achieve the desired/optimal
functionalities are favo-rable due to their cheap performance.
maintenance and convenient deployments [2]. In
order to achieve a certain mission, it is usually
The intelligent information society of 2030 is expected
desirable to deploy a collection or swarm of drones
to be globally information driven, highly digitized, with
in a networked fashion [3]. Such drone networks
the support of unlimited and near instant complete wire‑
or Drone Sensor Networks (DSNs) can monitor a less connectivity [4]. 6G, here, will be the prime catalyst
large coverage area and the sensed data can be for achieving this target, connecting everything, including
gathered with enhanced reliability, resilience and wireless coverage in all dimensions, as well as concate‑
fault tolerance under diverse conditions. nating almost all different functions such as, communi‑
DSNs can be highly viable in many real‑world scenarios: cation, sensing, imaging, computing, caching, navigation
For military surveillance applications (Fig. 1(a)), DSNs (e.g., radars), control, for supporting nearly all real‑world
can monitor a sensitive area, such as across international applications [5]. As wireless communications are rapidly
borders, where highly delicate military data (in the form progressing towards 6G, from the exponentially growing
of images or videos) can be transmitted securely. In network traf ic arises need of exploiting the electroma-
addition to the communications perspective, DSNs in‑ gnetic spectrum above the existing sub 6 GHz bands,
volving drones with sensing and processing capabilities which are almost saturated. A possible solution to this
can be utilized in some applications, such as disaster need is to utilize the Terahertz (THz) band (0.1‑10 THz)
management, for instance for detecting dangerous gases [6], as the bridge between the 5G millimeter wave band
(Fig. 1(b)). Moreover, drone networks with drones with and the free space optics band [7, 8]. A THz band
base station‑like capabilities can provide seamless on‑ offers huge bandwidth, favorable for very high data rate

© International Telecommunication Union, 2021 1