52 research outputs found
A Survey of Air-to-Ground Propagation Channel Modeling for Unmanned Aerial Vehicles
In recent years, there has been a dramatic increase in the use of unmanned
aerial vehicles (UAVs), particularly for small UAVs, due to their affordable
prices, ease of availability, and ease of operability. Existing and future
applications of UAVs include remote surveillance and monitoring, relief
operations, package delivery, and communication backhaul infrastructure.
Additionally, UAVs are envisioned as an important component of 5G wireless
technology and beyond. The unique application scenarios for UAVs necessitate
accurate air-to-ground (AG) propagation channel models for designing and
evaluating UAV communication links for control/non-payload as well as payload
data transmissions. These AG propagation models have not been investigated in
detail when compared to terrestrial propagation models. In this paper, a
comprehensive survey is provided on available AG channel measurement campaigns,
large and small scale fading channel models, their limitations, and future
research directions for UAV communication scenarios
A Realistic 3D Non-Stationary Channel Model for UAV-to-Vehicle Communications Incorporating Fuselage Posture
Considering the unmanned aerial vehicle (UAV) three-dimensional (3D) posture,
a novel 3D non-stationary geometry-based stochastic model (GBSM) is proposed
for multiple-input multiple-output (MIMO) UAV-to-vehicle (U2V) channels. It
consists of a line-of-sight (LoS) and non-line-of-sight (NLoS) components. The
factor of fuselage posture is considered by introducing a time-variant 3D
posture matrix. Some important statistical properties, i.e. the temporal
autocorrelation function (ACF) and spatial cross correlation function (CCF),
are derived and investigated. Simulation results show that the fuselage posture
has significant impact on the U2V channel characteristic and aggravate the
non-stationarity. The agreements between analytical, simulated, and measured
results verify the correctness of proposed model and derivations. Moreover, it
is demonstrated that the proposed model is also compatible to the existing GBSM
without considering fuselage posture.Comment: 12 pages, 8 figures, CNCO
Multiple Access in Aerial Networks: From Orthogonal and Non-Orthogonal to Rate-Splitting
Recently, interest on the utilization of unmanned aerial vehicles (UAVs) has
aroused. Specifically, UAVs can be used in cellular networks as aerial users
for delivery, surveillance, rescue search, or as an aerial base station (aBS)
for communication with ground users in remote uncovered areas or in dense
environments requiring prompt high capacity. Aiming to satisfy the high
requirements of wireless aerial networks, several multiple access techniques
have been investigated. In particular, space-division multiple access(SDMA) and
power-domain non-orthogonal multiple access (NOMA) present promising
multiplexing gains for aerial downlink and uplink. Nevertheless, these gains
are limited as they depend on the conditions of the environment. Hence, a
generalized scheme has been recently proposed, called rate-splitting multiple
access (RSMA), which is capable of achieving better spectral efficiency gains
compared to SDMA and NOMA. In this paper, we present a comprehensive survey of
key multiple access technologies adopted for aerial networks, where aBSs are
deployed to serve ground users. Since there have been only sporadic results
reported on the use of RSMA in aerial systems, we aim to extend the discussion
on this topic by modelling and analyzing the weighted sum-rate performance of a
two-user downlink network served by an RSMA-based aBS. Finally, related open
issues and future research directions are exposed.Comment: 16 pages, 6 figures, submitted to IEEE Journa
Outage probability based on telecommunication range for multi-hop HALE UAVs
Cooperative relaying increases telecommunication range, improves the connectivity, and increases the reliability of data transmission; however, the transmitted power does not change. This paper analyzes the extended telecommunication range of a multi-hop cascaded network comprising N–cooperative relaying high-altitude long endurance (HALE) unmanned aerial vehicles (UAVs) under ambient conditions. A notable ambient condition is rain, which causes signals to scatter in different directions; hence, one should model the communication channel for HALE UAV as a Rayleigh channel. This paper proposes a statistical model that is based on the effect of the telecommunication range on the outage probability in an N-Rayleigh fading channel. The simulation results show that as the telecommunication range increases, the outage probability (Poutage) also increases, whereas when both the telecommunication range and the number of relays increase, Poutage decreases. An issue that has been highlighted in this paper is that, by increasing number of relays from N=1 to N=5 the telecommunication range increases and Poutage about 40% decreases. Moreover, in rainy conditions and with a fixed number of relays, when both the intensity of rainfall and telecommunication range increases, Poutage increases. For example by increasing rate of rain (Rr) from 1mm/h to 100 mm/h, Poutage increases around 30% in 100 Km with two relays
Map-based Channel Modeling and Generation for U2V mmWave Communication
Unmanned aerial vehicle (UAV) aided millimeter wave (mmWave) technologies
have a promising prospect in the future communication networks. By considering
the factors of three-dimensional (3D) scattering space, 3D trajectory, and 3D
antenna array, a non-stationary channel model for UAV-to-vehicle (U2V) mmWave
communications is proposed. The computation and generation methods of channel
parameters including interpath and intra-path are analyzed in detail. The
inter-path parameters are calculated in a deterministic way, while the
parameters of intra-path rays are generated in a stochastic way. The
statistical properties are obtained by using a Gaussian mixture model (GMM) on
the massive ray tracing (RT) data. Then, a modified method of equal areas
(MMEA) is developed to generate the random intra-path variables. Meanwhile, to
reduce the complexity of RT method, the 3D propagation space is reconstructed
based on the user-defined digital map. The simulated and analyzed results show
that the proposed model and generation method can reproduce non-stationary U2V
channels in accord with U2V scenarios. The generated statistical properties are
consistent with the theoretical and measured ones as well
Classification and comparison of massive MIMO propagation channel models
Considering great benefits brought by massive multiple-input multiple-output (MIMO) technologies in Internet of things (IoT), it is of vital importance to analyze new massive MIMO channel characteristics and develop corresponding channel models. In the literature, various massive MIMO channel models have been proposed and classified with different but confusing methods, i.e., physical vs. analytical method and deterministic vs. stochastic method. To have a better understanding and usage of massive MIMO channel models, this work summarizes different classification methods and presents an up-to-date unified classification framework, i.e., artificial intelligence (AI)-based predictive channel models and classical non-predictive channel models, which further clarify and combine the deterministic vs. stochastic and physical vs. analytical methods. Furthermore, massive MIMO channel measurement campaigns are reviewed to summarize new massive MIMO channel characteristics. Recent advances in massive MIMO channel modeling are surveyed. In addition, typical non-predictive massive MIMO channel models are elaborated and compared, i.e., deterministic models and stochastic models, which include correlation-based stochastic model (CBSM), geometry-based stochastic model (GBSM), and beam domain channel model (BDCM). Finally, future challenges in massive MIMO channel modeling are given
Air-to-Ground Channel Characterization for Low-Height UAVs in Realistic Network Deployments
Due to the decrease in cost, size and weight, \acp{UAV} are becoming more and
more popular for general-purpose civil and commercial applications. Provision
of communication services to \acp{UAV} both for user data and control messaging
by using off-the-shelf terrestrial cellular deployments introduces several
technical challenges. In this paper, an approach to the air-to-ground channel
characterization for low-height \acp{UAV} based on an extensive measurement
campaign is proposed, giving special attention to the comparison of the results
when a typical directional antenna for network deployments is used and when a
quasi-omnidirectional one is considered. Channel characteristics like path
loss, shadow fading, root mean square delay and Doppler frequency spreads and
the K-factor are statistically characterized for different suburban scenarios.Comment: 15 pages, accepted in IEEE Transactions on Antennas and Propagatio
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