1,509 research outputs found
Mobile Unmanned Aerial Vehicles (UAVs) for Energy-Efficient Internet of Things Communications
In this paper, the efficient deployment and mobility of multiple unmanned
aerial vehicles (UAVs), used as aerial base stations to collect data from
ground Internet of Things (IoT) devices, is investigated. In particular, to
enable reliable uplink communications for IoT devices with a minimum total
transmit power, a novel framework is proposed for jointly optimizing the
three-dimensional (3D) placement and mobility of the UAVs, device-UAV
association, and uplink power control. First, given the locations of active IoT
devices at each time instant, the optimal UAVs' locations and associations are
determined. Next, to dynamically serve the IoT devices in a time-varying
network, the optimal mobility patterns of the UAVs are analyzed. To this end,
based on the activation process of the IoT devices, the time instances at which
the UAVs must update their locations are derived. Moreover, the optimal 3D
trajectory of each UAV is obtained in a way that the total energy used for the
mobility of the UAVs is minimized while serving the IoT devices. Simulation
results show that, using the proposed approach, the total transmit power of the
IoT devices is reduced by 45% compared to a case in which stationary aerial
base stations are deployed. In addition, the proposed approach can yield a
maximum of 28% enhanced system reliability compared to the stationary case. The
results also reveal an inherent tradeoff between the number of update times,
the mobility of the UAVs, and the transmit power of the IoT devices. In
essence, a higher number of updates can lead to lower transmit powers for the
IoT devices at the cost of an increased mobility for the UAVs.Comment: Accepted in IEEE Transactions on Wireless Communications, Sept. 201
Drone Small Cells in the Clouds: Design, Deployment and Performance Analysis
The use of drone small cells (DSCs) which are aerial wireless base stations
that can be mounted on flying devices such as unmanned aerial vehicles (UAVs),
is emerging as an effective technique for providing wireless services to ground
users in a variety of scenarios. The efficient deployment of such DSCs while
optimizing the covered area is one of the key design challenges. In this paper,
considering the low altitude platform (LAP), the downlink coverage performance
of DSCs is investigated. The optimal DSC altitude which leads to a maximum
ground coverage and minimum required transmit power for a single DSC is
derived. Furthermore, the problem of providing a maximum coverage for a certain
geographical area using two DSCs is investigated in two scenarios; interference
free and full interference between DSCs. The impact of the distance between
DSCs on the coverage area is studied and the optimal distance between DSCs
resulting in maximum coverage is derived. Numerical results verify our
analytical results on the existence of optimal DSCs altitude/separation
distance and provide insights on the optimal deployment of DSCs to supplement
wireless network coverage
Efficient Deployment of Multiple Unmanned Aerial Vehicles for Optimal Wireless Coverage
In this paper, the efficient deployment of multiple unmanned aerial vehicles
(UAVs) with directional antennas acting as wireless base stations that provide
coverage for ground users is analyzed. First, the downlink coverage probability
for UAVs as a function of the altitude and the antenna gain is derived. Next,
using circle packing theory, the three-dimensional locations of the UAVs is
determined in a way that the total coverage area is maximized while maximizing
the coverage lifetime of the UAVs. Our results show that, in order to mitigate
interference, the altitude of the UAVs must be properly adjusted based on the
beamwidth of the directional antenna as well as coverage requirements.
Furthermore, the minimum number of UAVs needed to guarantee a target coverage
probability for a given geographical area is determined. Numerical results
evaluate the various tradeoffs involved in various UAV deployment scenarios.Comment: Accepted in the IEEE Communications Letter
Unmanned Aerial Vehicle with Underlaid Device-to-Device Communications: Performance and Tradeoffs
In this paper, the deployment of an unmanned aerial vehicle (UAV) as a flying
base station used to provide on the fly wireless communications to a given
geographical area is analyzed. In particular, the co-existence between the UAV,
that is transmitting data in the downlink, and an underlaid device-todevice
(D2D) communication network is considered. For this model, a tractable
analytical framework for the coverage and rate analysis is derived. Two
scenarios are considered: a static UAV and a mobile UAV. In the first scenario,
the average coverage probability and the system sum-rate for the users in the
area are derived as a function of the UAV altitude and the number of D2D users.
In the second scenario, using the disk covering problem, the minimum number of
stop points that the UAV needs to visit in order to completely cover the area
is computed. Furthermore, considering multiple retransmissions for the UAV and
D2D users, the overall outage probability of the D2D users is derived.
Simulation and analytical results show that, depending on the density of D2D
users, optimal values for the UAV altitude exist for which the system sum-rate
and the coverage probability are maximized. Moreover, our results also show
that, by enabling the UAV to intelligently move over the target area, the total
required transmit power of UAV while covering the entire area, is minimized.
Finally, in order to provide a full coverage for the area of interest, the
tradeoff between the coverage and delay, in terms of the number of stop points,
is discussed.Comment: accepted in the IEEE Transactions on Wireless Communication
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