Interference Avoidance Position Planning in UAV-Assisted Wireless Communication (original) (raw)
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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.
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 ...
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.
Joint Mobility-Aware UAV Placement and Routing in Multi-Hop UAV Relaying Systems
Ad Hoc Networks, 2021
Unmanned Aerial Vehicles (UAVs) have been extensively utilized to provide wireless connectivity in rural and underdeveloped areas, enhance network capacity and provide support for peaks or unexpected surges in user demand, mainly due to their fast deployment, cost-efficiency and superior communication performance resulting from Line of Sight (LoS)-dominated wireless channels. In order to exploit the benefits of UAVs as base stations or relays in a mobile network, a major challenge is to determine the optimal UAV placement and relocation strategy with respect to the mobility and traffic patterns of the ground network nodes. Moreover, considering that the UAVs form a multi-hop aerial network, capacity and connectivity constraints have significant impacts on the end-to-end network performance. To this end, we formulate the joint UAV placement and routing problem as a Mixed Integer Linear Program (MILP) and propose an approximation that leads to a LP rounding algorithm and achieves a balance between time-complexity and optimality.
Joint Location and Beamforming Design for Cooperative UAVs With Limited Storage Capacity
IEEE Transactions on Communications, 2019
In this paper, we investigate downlink transmissions in a wireless communication system enabled by a swarm of unmanned aerial vehicles (UAVs) which are spatially dispatched to cooperatively deliver requested contents to ground users. First, we propose a communication scheme that exploits the flexible deployment of UAVs as well as their cooperative transmissions to improve in-network user admission. Unlike previous literature, a practical operational constraint of limited storage capacity for UAVs is considered. Then, from the knowledge that cooperation among UAVs depends on the availability of the contents in their limited storage space, we propose a novel joint optimization problem to determine the content placement, location planning, user admission decision and transmit beamforming to maximize the number of users experiencing a minimum required rate, so-called admitted users. Since the formulated problem is a mixed-integer non-linear program which is generally nondeterministic polynomial-time hard, we proposed a framework that is developed on the basis of difference-of-convex (DC) programming to transform the original problem into a series of approximate convex problems which can be iteratively solved until convergence. Our extensive simulation results reveal that the proposed scheme outperforms other schemes that have been introduced in previous work and reflect a notable trend that deploying more cooperative UAVs with fewer resources (power and storage capacity) is more efficient than deploying fewer UAVs with more resources. In particular, in one of our collected results, the total communication power can be reduced by roughly 40 dB when doubling the number of cooperative UAVs.
Non-Cooperative Aerial Base Station Placement via Stochastic Optimization
2019 15th International Conference on Mobile Ad-Hoc and Sensor Networks (MSN), 2019
Autonomous unmanned aerial vehicles (UAVs) with on-board base station equipment can potentially provide connectivity in areas where the terrestrial infrastructure is overloaded, damaged, or absent. Use cases comprise emergency response, wildfire suppression, surveillance, and cellular communications in crowded events to name a few. A central problem to enable this technology is to place such aerial base stations (AirBSs) in locations that approximately optimize the relevant communication metrics. To alleviate the limitations of existing algorithms, which require intensive and reliable communications among AirBSs or between the AirBSs and a central controller, this paper leverages stochastic optimization and machine learning techniques to put forth an adaptive and decentralized algorithm for AirBS placement without inter-AirBS cooperation or communication. The approach relies on a smart design of the network utility function and on a stochastic gradient ascent iteration that can be evaluated with information available in practical scenarios. To complement the theoretical convergence properties, a simulation study corroborates the effectiveness of the proposed scheme.
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.
2019 1st International Conference on Unmanned Vehicle Systems-Oman (UVS), 2019
Unmanned aerial vehicles mounted base stations (UAV-BSs) are expected to become one of the significant components of the Next Generation Wireless Networks (NGWNs). Rapid deployment, mobility, higher chances of unobstructed propagation path, and flexibility features of UAV-BSs have attracted significant attention. Despite, potentially, high gains brought by UAV-BSs in NGWNs, many challenges are also introduced by them. Optimal location assignment to UAV-BSs, arguably, is the most widely investigated problem in the literature on UAV-BSs in NGWNs. This paper presents a comprehensive survey of the literature on the location optimization of UAV-BSs in NGWNs. A generic optimization framework through a universal Mixed Integer Non-Linear Programming (MINLP) formulation is constructed and the specifications of its constituents are elaborated. The generic problem is classified into a novel taxonomy. Due to the highly challenging nature of the optimization problem a range of solutions are adopted in the literature which are also covered under the aforementioned classification. Furthermore, future research directions on UAV-BS location optimization in 5G and beyond non-terrestrial aerial communication systems are discussed.
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, ...
Simultaneous User Association and Placement in Multi-UAV Enabled Wireless Networks
2018
In this paper, we are proposing a map-based approach for the optimal placement of multiple UAV-based flying wireless relays in a cellular network. The tackled problem is two-fold, involving a joint UAV-user association problem and 3D placement problem. While related problems were addressed before, the novelty of our approach lies in the fact it builds on a combination of probabilistic and deterministic line-of-sight (LoS) classifiers which exploits the availability of a 3D city map. While the original problem is very challenging in its dimension, we give a low-complexity approach to the placement problem by approximating the optimum UAV positions with a suitably weighted combination of user positions. Our simulations suggest a performance close to that obtained with high complexity exhaustive search for placement.