iTUAVs: Intermittently Tethered UAVs for Future Wireless Networks

Abstract

We propose the intermittently tethered unmanned aerial vehicle (iTUAV) as a tradeoff between the power availability of a tethered UAV (TUAV) and flexibility of an untethered UAV. An iTUAV can provide cellular connectivity while being temporarily tethered to the most adequate ground anchor. Also, it can flexibly detach from one anchor, travel, then attach to another one to maintain/improve the coverage quality for mobile users. Hence, we discuss here the existing UAV-based cellular networking technologies, followed by a detailed description of the iTUAV system, its components, and mode of operation. Subsequently, we present a comparative study of the existing and proposed systems highlighting the differences of key features such as mobility and energy. To emphasize the potential of iTUAV systems, we conduct a case study, evaluate the iTUAV performance, and compare it to benchmarks. Obtained results show that with only 10 anchors in the area, the iTUAV system can serve up to 90% of the users covered by the untethered UAV swapping system. Moreover, results for a small case study prove that the iTUAV allows to balance performance/cost and can be implemented realistically. For instance, when user locations are clustered, with only 2 active iTUAVs and 4 anchors, achieved performance is superior to that of the system with 3 TUAVs, while when considering a single UAV on a 100 minutes event, a system with only 6 anchors outperforms the untethered UAV as it combines location flexibility with increased mission time.

Optimal Location of Cellular Base Stations via Convex Optimization: An Analytical Framework and Numerical Algorithms

“…A set of locations to which optimal T-UAV location belongs is identified, and, since the remaining problems are analytically untractable, simulated annealing or exhaustive search are used. Intermittently tethered UAVs (iTUAVS) are proposed in [27] as a trade-off solution to combine the advantages of untethered and tethered UAVs. Optimal UAV placement is formulated in [24] as a constrained optimization problem to maximize fair coverage to energy consumption ratio while satisfying backhaul constraints.…”

Tethered UAV Deployment Strategies: The Coverage and Energy Efficiency Trade-Off

“…It investigates the deployment of a TUAV to collect data from IoT devices and compares it to laser-powered UAV and rechargeable UAV in terms of service quality and traveled distance, using Monte-Carlo simulations. Along with this trend, [29] study a system composed of a single Intermittently Tethered UAV (iTUAV), which is a TUAV with attachment and detachment capability, to provide wireless coverage in areas without network infrastructure. It evaluates the coverage performance of the system and compares it to UAV and TUAV counterparts.…”

“…Unlike [29] which analyze single-TUAV systems, we study large-scale TUAV systems where users are uniformly distributed inside clusters. we propose three different TUAV deployment strategies taking into consideration the change of spatial distribution of mobile users over time, which was not considered in [10].…”

A Geometry-Based Modelling Approach for the Line-of-Sight Probability in UAV Communications

“…The primary reasons for their increasing popularity are their flexible maneuverability, rapid deployment, and low cost [4]- [6]. Because of these advantages, UAVs as NodeB (UxNBs) are considered to provide coverage in emergent scenarios, such as disaster relief, infrastructureshortage areas, or hot-spot ultra-dense areas where Ground NodeBs (GNBs) are insufficient to meet communication demands [7], [8].…”