Joint 3-D Positioning and Power Allocation for UAV Relay Aided by Geographic Information (original) (raw)

UAV-relay Placement with Unknown User Locations and Channel Parameters

2018 52nd Asilomar Conference on Signals, Systems, and Computers, 2018

This work investigates the problem of optimal placement of an UAV that provides communication services by acting as a flying wireless relay between a fixed base station (BS) and ground users. The proposed approach builds on the knowledge of the terrain topology where the network is deployed and aims at finding the optimal position of the UAV that maximizes the throughput in the max-min sense. Different from prior works, we do not assume any prior knowledge on user locations and the underlying wireless channel pathloss parameters. We first jointly estimate the user location and the pathloss parameters from the measurements collected by the UAV, and then use them to find the optimal relay position. When it comes to the optimal placement, an iterative algorithm is provided which iterates between the planar UAV placement and altitude optimization by exploiting the 3D city map information.

3D Placement of a New Tethered UAV to UAV Relay System for Coverage Maximization

2021

In this paper, a new relay system that uses the UAV as a relay station between the tethered UAV and ground user (TU2U2G) is proposed. The TU2U2G system replaces the base station (BS) in the cellular system with a tethered UAV (TUAV). The TUAV is a UAV that receives power over a cable from a ground control station. It has advantages of high and variable altitude up to (100m) compared to BS. In addition, it overcomes the UAV drawback of the batteries' limited capacity. After that, a 3D placement Algorithm of the UAV as a relay station in the TU2U2G system is proposed. It is presented to maximize the coverage by jointly optimizing the transmitting power and relaying distance. The TU2U2G system shows better results than the traditional cellular system in terms of optimum UAV height, maximum coverage radius, and maximum distance between BS and UAV.

On the Optimal 3D Placement of a UAV Base Station for Maximal Coverage of UAV Users

2020

Unmanned aerial vehicles (UAVs) can be users that support new applications, or be communication access points that serve terrestrial and/or aerial users. In this paper, we focus on the connectivity problem of aerial users when they are exclusively served by aerial base stations (BS), i.e., UAVBSs. Specifically, the 3D placement problem of a directionalantenna equipped UAV-BS, aiming to maximize the number of covered aerial users under a spectrum sharing policy with terrestrial networks, is investigated. Given a known spectrum sharing policy between the aerial and terrestrial networks, we propose a 3D placement algorithm that achieves optimality. Simulation results show the performance of our approach, in terms of number of covered aerial users for different configurations and parameters, such as the spectrum sharing policy, antenna beamwidth, transmit power, and aerial users density. These results represent novel guidelines for exclusive aerial networks deployment and applications, ...

Positioning Optimization of UAV (Drones) Base Station in Communication Networks

Malaysian Journal of Fundamental and Applied Sciences

Unmanned aerial vehicles (UAV) and cellular networks are growing closer to being integrated in the realm of wireless communications, which will improve service quality even further. In this study, we investigate a wireless communication system in which two types of base stations—in the air and on the ground—serve separate groups of users. We analyze the effect of the aerial base station (ABS) height and transmit power on the system's downlink and uplink data rates while accounting for the reciprocal interference between the Aerial and terrestrial communication lines. The findings demonstrate that in many cases the best ABS altitude and transmit Power are either the highest or lowest values attainable. The distance between the ABS, the ABS user (AU), and the terrestrial base station user, among other factors, may affect how well they all communicate (TU). In this article we will discuss the following topics: unmanned aerial vehicle (UAV), terrestrial base station (BTS), transmit ...

Efficient Placement of an Aerial Relay Drone for Throughput Maximization

2021

Unmanned aerial vehicle (UAV) communication can be used in overcrowded areas and either during or postdisaster situations as an evolving technology to provide ubiquitous connections for wireless devices due to its flexibility, mobility, and good condition of the line of sight channels. In this paper, a single UAV is used as an aerial relay node to provide connectivity to wireless devices because of the considerable distance between wireless devices and the ground base station. Specifically, two path loss models have been utilized; a cellular-to-UAV path loss for a backhaul connection and an air-to-ground path loss model for a downlink connection scenario. Then, the tradeoff introduced by these models is discussed. The problem of efficient placement of an aerial relay node is formulated as an optimization problem, where the objective is to maximize the total throughput of wireless devices. To find an appropriate location for a relay aerial node that maximizes the overall throughput, ...

Joint Optimization of Altitude and Transmission Direction in UAV-Based Two-Way Communication

IEEE Wireless Communications Letters, 2019

Unmanned Aerial Vehicles (UAVs) can be used as flying Base Stations (BSs). When one-way communication is considered, either uplink or downlink, the system performance is limited by the strong co-channel interference that takes place over the UAV-ground channel. This work considers twoway communication and takes advantage of the fact that the interference over ground-ground channel is likely lower than the one over the UAV-ground channel. This sets the stage for joint optimization of the user association, UAV altitude, and transmission direction, which is shown to lead to improved system throughput for a given known placement of the ground devices. Index Terms-Unmanned Aerial Vehicle (UAV), UAV two-way communication, interference spin. I. INTRODUCTION A number of recent works have considered the use of unmanned aerial vehicles (UAVs) as flying Base Stations (BSs) to provide data services to ground users, see [1] and the references therein. Compared to a traditional terrestrial BS, UAV can provide higher capacity since line-of-sight (LoS) wireless communication link can be easily established in UAVground channel [2]. Moreover, multiple UAVs are considered to enhance coverage as well as throughput with the increasing dense deployment for UAVs [3], [4], [5]. Besides the benefits of this flexible BS deployment, there are also a number of challenges, such as cell partition according to user distribution, UAV altitude adjustment and interference management, etc [1]. Furthermore, while the UAV-ground channel with strong LoS component is beneficial for the useful signal, it should be noted that, when one-way communication (either uplink or downlink) is considered, the co-channel interference always comes through the UAV-ground channel. The authors in [6] used evolutionary algorithms in order to find the optimal placement of UAVs to in disaster relief scenarios and their results in shows that increasing the number of UAVs will inevitably lead to interference due to overlapping areas. In [3], in order to maximize the downlink coverage, the authors proposed an efficient deployment method for multiple UAVs using circle packing theory, while ensuring that the coverage areas of UAVs do not overlap. The authors in [4] considered uplink transmission from UAVs to ground BSs. A communication blockage occurs if a UAV cannot find a BS or there are other BSs stations in its main lobe serving other UAVs, and hence suffer from strong co-channel interference.

3-D Trajectory Optimization for Fixed-Wing UAV-Enabled Wireless Network

IEEE Access, 2021

Unmanned aerial vehicles (UAVs) is a promising technology for the next-generation communication systems. In this article, a fixed-wing UAV is considered to enhance the connectivity for far-users at the coverage region of an overcrowded base station (BS). In particular, a three dimensions (3D) UAV trajectory is optimized to improve the overall energy efficiency of the communication system by considering the system throughput and the UAV's energy consumption for a given finite time horizon. The solutions for the proposed optimization problem are derived by applying Lagrangian optimization and using an algorithm based on successive convex iteration techniques. Numerical results demonstrate that by optimizing the UAV's trajectory in the 3D space, the proposed system design achieves significantly higher energy efficiency with the gain reaching up to 20 bitsJ −1 compared to the 14 bitsJ −1 maximum gain achieved by the 2D space trajectory. Further, results reveal that the proposed algorithm converge earlier in 3D space trajectory compare to the 2D space trajectory.

Optimum UAV positioning for better coverage-connectivity tradeoff

2017 IEEE 28th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC)

Unmanned aerial vehicle (UAV) plays prominent role in enhancing backhaul connectivity and providing extended coverage areas due to its mobility and flexible deployment. To realize these objectives simultaneously, we present a new framework for positioning the UAV to maximize the small-cells backhaul network connectivity characterized by its Fiedler value, the second smallest eigenvalue of the Laplacian matrix representing the network graph, while maintaining particular signal-to-noise ratio constraint for each individual user equipment. Moreover, we show that the localization problem can be approximated by a low complexity convex semi-definite programming optimization problem. Finally, our extensive simulations verify the approximation validity and demonstrate the potential gain of UAV deployment.

3-D Dynamic UAV Base Station Location Problem

INFORMS Journal on Computing, 2021

We address a dynamic covering location problem of an unmanned aerial vehicle base station (UAV-BS), in which the location sequence of a single UAV-BS in a wireless communication network is determined to satisfy data demand arising from ground users. This problem is especially relevant in the context of smart grid and disaster relief. The vertical movement ability of the UAV-BS and nonconvex covering functions in wireless communication restrict utilizing classical planar covering location approaches. Therefore, we develop new formulations to this emerging problem for a finite time horizon to maximize the total coverage. In particular, we develop a mixed-integer nonlinear programming formulation that is nonconvex in nature and propose a Lagrangean decomposition algorithm (LDA) to solve this formulation. Because of the high complexity of the problem, the LDA is still unable to find good local solutions to large-scale problems. Therefore, we develop a continuum approximation (CA) model ...

Hovering Localization and Power Allocation for UAV assisted DF Relaying Ad Hoc Network

An ad-hoc network using unmanned aerial vehicle (UAV) as relay, has been gaining significant attention especially for communication between far apart ground terminals during emergency conditions due to agility and resilience requirements. However, UAV hovering localization (HL) and power allocation (PA) are the key issues in such relay based flying ad hoc networks (FANETs). In this work, we propose a framework to jointly optimize the placement of rotary-wing UAV hovering and PA for maximization of network throughput in a three node decode-and-forward (DF) FANET. Specifically, we develop three different optimization schemes, (i) individual UAV HL optimization with a fixed allocated power, (ii) individual PA optimization for a fixed UAV HL, (iii) jointly optimal UAV HL and PA. For every optimization problem, the underlying convexity is proved and the global optimal solutions have been obtained. Further, we provide novel analysis by utilizing the characteristics of sigmoidal function t...