5 research outputs found
Multi-layer Unmanned Aerial Vehicle Networks: Modeling and Performance Analysis
Since various types of unmanned aerial vehicles (UAVs) with different
hardware capabilities are introduced, we establish a foundation for the
multi-layer aerial network (MAN). First, the MAN is modeled as K layer ANs, and
each layer has UAVs with different densities, floating altitudes, and
transmission power. To make the framework applicable for various scenarios in
MAN, we consider the transmitter- and the receiver-oriented node association
rules as well as the air-to-ground and air-to-air channel models, which form
line of sight links with a location-dependent probability. We then newly
analyze the association probability, the main link distance distribution,
successful transmission probability (STP), and area spectral efficiency (ASE)
of MAN. The upper bounds of the optimal densities that maximize STP and ASE are
also provided. Finally, in the numerical results, we show the optimal UAV
densities of an AN that maximize the ASE and the STP decrease with the altitude
of the network. We also show that when the total UAV density is fixed for two
layer AN, the use of single layer in higher(lower) altitude only for all UAVs
can achieve better performance for low(high) total density case, otherwise,
distributing UAVs in two layers, i.e., MAN, achieves better performance
Impact of an Interfering Node on Unmanned Aerial Vehicle Communications
Unlike terrestrial communications, unmanned aerial vehicle (UAV)
communications have some advantages such as the line-of-sight (LoS) environment
and flexible mobility. However, the interference will be still inevitable. In
this paper, we analyze the effect of an interfering node on the UAV
communications by considering the LoS probability and different channel fading
for LoS and non-line-of-sight (NLoS) links, which are affected by the elevation
angle of the communication link. We then derive a closed-form outage
probability in the presence of an interfering node for all the possible
scenarios and environments of main and interference links. After discussing the
impacts of transmitting and interfering node parameters on the outage
probability, we show the existence of the optimal height of the UAV that
minimize the outage probability. We also show the NLoS environment can be
better than the LoS environment if the average received power of the
interference is more dominant than that of the transmitting signal on UAV
communications. Finally, we analyze the outage probability for the case of
multiple interfering nodes using stochastic geometry and the outage probability
of the single interfering node case, and show the effect of the interfering
node density on the optimal height of the UAV.Comment: 12 pages, 10 figures, this paper has been submitted in IEEE
Transactions on Vehicular Technology. arXiv admin note: substantial text
overlap with arXiv:1806.0984
Non-Terrestrial Networks for UAVs: Base Station Service Provisioning Schemes with Antenna Tilt
By focusing on unmanned aerial vehicle (UAV) communications in
non-terrestrial networks (NTNs), this paper provides a guideline on the
appropriate base station (BS) service provisioning scheme with considering the
antenna tilt angle of BS. Specifically, two service provisioning schemes are
considered including the inclusive-service BS (IS-BS) scheme, which makes BSs
serve both ground users (GUs) and aerial users (AUs) (i.e., UAVs)
simultaneously, and the exclusive-service BS (ES-BS) scheme, which has BSs for
GUs and BSs for AUs. By considering the antenna tilt angle-based channel gain,
we derive the network outage probability for both IS-BS and ES-BS schemes, and
show the existence of the optimal tilt angle that minimizes the network outage
probability after analyzing the conflict impact of the antenna tilt angle. We
also analyze the impact of various network parameters, including the ratio of
GUs to total users and densities of total and interfering BSs, on the network
outage probability. Finally, we analytically and numerically show in which
environments each service provisioning scheme can be superior to the other one