282 research outputs found
Coverage maximization for a poisson field of drone cells
The use of drone base stations to provide wireless connectivity for ground terminals is becoming a promising part of future technologies. The design of such aerial networks is however different compared to cellular 2D networks, as antennas from the drones are looking down, and the channel model becomes height-dependent. In this paper, we study the effect of antenna patterns and height-dependent shadowing. We consider a random network topology to capture the effect of dynamic changes of the flying base stations. First we characterize the aggregate interference imposed by the co-channel neighboring drones. Then we derive the link coverage probability between a ground user and its associated drone base station. The result is used to obtain the optimum system parameters in terms of drones antenna beamwidth, density and altitude. We also derive the average LoS probability of the associated drone and show that it is a good approximation and simplification of the coverage probability in low altitudes up to 500 m according to the required signal-to-interference-plus-noise ratio (SINR)
Underlay Drone Cell for Temporary Events: Impact of Drone Height and Aerial Channel Environments
Providing seamless connection to a large number of devices is one of the
biggest challenges for the Internet of Things (IoT) networks. Using a drone as
an aerial base station (ABS) to provide coverage to devices or users on ground
is envisaged as a promising solution for IoT networks. In this paper, we
consider a communication network with an underlay ABS to provide coverage for a
temporary event, such as a sporting event or a concert in a stadium. Using
stochastic geometry, we propose a general analytical framework to compute the
uplink and downlink coverage probabilities for both the aerial and the
terrestrial cellular system. Our framework is valid for any aerial channel
model for which the probabilistic functions of line-of-sight (LOS) and
non-line-of-sight (NLOS) links are specified. The accuracy of the analytical
results is verified by Monte Carlo simulations considering two commonly adopted
aerial channel models. Our results show the non-trivial impact of the different
aerial channel environments (i.e., suburban, urban, dense urban and high-rise
urban) on the uplink and downlink coverage probabilities and provide design
guidelines for best ABS deployment height.Comment: This work is accepted to appear in IEEE Internet of Things Journal
Special Issue on UAV over IoT. Copyright may be transferred without notice,
after which this version may no longer be accessible. arXiv admin note: text
overlap with arXiv:1801.0594
Dynamic Standalone Drone-Mounted Small Cells
This paper investigates the feasibility of Dynamic Horizontal Opportunistic
Positioning (D-HOP) use in Drone Small Cells (DSCs), with a central analysis on
the impact of antenna equipment efficiency onto the optimal DSC altitude that
has been chosen in favor of maximizing coverage. We extend the common urban
propagation model of an isotropic antenna to account for a directional antenna,
making it dependent on the antenna's ability to fit the ideal propagation
pattern. This leads us to define a closed-form expression for calculating the
Rate improvement of D-HOP implementations that maintain constant coverage
through antenna tilting. Assuming full knowledge of the uniformly distributed
active users' locations, three D-HOP techniques were tested: in the center of
the Smallest Bounding Circle (SBC); the point of Maximum Aggregated Rate (MAR);
and the Center-Most Point (CMP) out of the two aforementioned. Through analytic
study and simulation we infer that DSC D-HOP implementations are feasible when
using electrically small and tiltable antennas. Nonetheless, it is possible to
achieve average per user average rate increases of up to 20-35% in low user
density scenarios, or 3-5% in user-dense scenarios, even when using efficient
antennas in a DSC that has been designed for standalone coverage.Comment: To be published in proceedings of EuCNC'2
Uplink Coverage Performance of an Underlay Drone Cell for Temporary Events
Using a drone as an aerial base station (ABS) to provide coverage to users on
the ground is envisaged as a promising solution for beyond fifth generation
(beyond-5G) wireless networks. While the literature to date has examined
downlink cellular networks with ABSs, we consider an uplink cellular network
with an ABS. Specifically, we analyze the use of an underlay ABS to provide
coverage for a temporary event, such as a sporting event or a concert in a
stadium. Using stochastic geometry, we derive the analytical expressions for
the uplink coverage probability of the terrestrial base station (TBS) and the
ABS. The results are expressed in terms of (i) the Laplace transforms of the
interference power distribution at the TBS and the ABS and (ii) the distance
distribution between the ABS and an independently and uniformly distributed
(i.u.d.) ABS-supported user equipment and between the ABS and an i.u.d.
TBS-supported user equipment. The accuracy of the analytical results is
verified by Monte Carlo simulations. Our results show that varying the ABS
height leads to a trade-off between the uplink coverage probability of the TBS
and the ABS. In addition, assuming a quality of service of 90% at the TBS, an
uplink coverage probability of the ABS of over 85% can be achieved, with the
ABS deployed at or below its optimal height of typically between 250-500 m for
the considered setup.Comment: This work is accepted to 2018 IEEE International Conference on
Communications Workshops (ICC Workshops): Integrating UAVs into 5
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