4,970 research outputs found
Stochastic Geometry Modeling and Performance Evaluation of mmWave Cellular Communications
In this paper, a new mathematical framework to the analysis of millimeter
wave cellular networks is introduced. Its peculiarity lies in considering
realistic path-loss and blockage models, which are derived from experimental
data recently reported in the literature. The path-loss model accounts for
different distributions for line-of-sight and non-line-of-sight propagation
conditions and the blockage model includes an outage state that provides a
better representation of the outage possibilities of millimeter wave
communications. By modeling the locations of the base stations as points of a
Poisson point process and by relying upon a noise-limited approximation for
typical millimeter wave network deployments, exact integral expressions for
computing the coverage probability and the average rate are obtained. With the
aid of Monte Carlo simulations, the noise-limited approximation is shown to be
sufficiently accurate for typical network densities. Furthermore, it is shown
that sufficiently dense millimeter wave cellular networks are capable of
outperforming micro wave cellular networks, both in terms of coverage
probability and average rate.Comment: Presented at 2015 IEEE International Conference on Communications
(ICC), London, UK (June 2015). arXiv admin note: substantial text overlap
with arXiv:1410.357
Wirelessly Powered Backscatter Communication Networks: Modeling, Coverage and Capacity
Future Internet-of-Things (IoT) will connect billions of small computing
devices embedded in the environment and support their device-to-device (D2D)
communication. Powering this massive number of embedded devices is a key
challenge of designing IoT since batteries increase the devices' form factors
and battery recharging/replacement is difficult. To tackle this challenge, we
propose a novel network architecture that enables D2D communication between
passive nodes by integrating wireless power transfer and backscatter
communication, which is called a wirelessly powered backscatter communication
(WP-BackCom) network. In the network, standalone power beacons (PBs) are
deployed for wirelessly powering nodes by beaming unmodulated carrier signals
to targeted nodes. Provisioned with a backscatter antenna, a node transmits
data to an intended receiver by modulating and reflecting a fraction of a
carrier signal. Such transmission by backscatter consumes orders-of-magnitude
less power than a traditional radio. Thereby, the dense deployment of
low-complexity PBs with high transmission power can power a large-scale IoT. In
this paper, a WP-BackCom network is modeled as a random Poisson cluster process
in the horizontal plane where PBs are Poisson distributed and active ad-hoc
pairs of backscatter communication nodes with fixed separation distances form
random clusters centered at PBs. The backscatter nodes can harvest energy from
and backscatter carrier signals transmitted by PBs. Furthermore, the
transmission power of each node depends on the distance from the associated PB.
Applying stochastic geometry, the network coverage probability and transmission
capacity are derived and optimized as functions of backscatter parameters,
including backscatter duty cycle and reflection coefficient, as well as the PB
density. The effects of the parameters on network performance are
characterized.Comment: 28 pages, 11 figures, has been submitted to IEEE Trans. on Wireless
Communicatio
Power Beacon-Assisted Millimeter Wave Ad Hoc Networks
Deployment of low cost power beacons (PBs) is a promising solution for
dedicated wireless power transfer (WPT) in future wireless networks. In this
paper, we present a tractable model for PB-assisted millimeter wave (mmWave)
wireless ad hoc networks, where each transmitter (TX) harvests energy from all
PBs and then uses the harvested energy to transmit information to its desired
receiver. Our model accounts for realistic aspects of WPT and mmWave
transmissions, such as power circuit activation threshold, allowed maximum
harvested power, maximum transmit power, beamforming and blockage. Using
stochastic geometry, we obtain the Laplace transform of the aggregate received
power at the TX to calculate the power coverage probability. We approximate and
discretize the transmit power of each TX into a finite number of discrete power
levels in log scale to compute the channel and total coverage probability. We
compare our analytical predictions to simulations and observe good accuracy.
The proposed model allows insights into effect of system parameters, such as
transmit power of PBs, PB density, main lobe beam-width and power circuit
activation threshold on the overall coverage probability. The results confirm
that it is feasible and safe to power TXs in a mmWave ad hoc network using PBs.Comment: This work has been submitted to the IEEE for possible publication.
Copyright may be transferred without notice, after which this version may no
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Millimeter Wave Cellular Networks: A MAC Layer Perspective
The millimeter wave (mmWave) frequency band is seen as a key enabler of
multi-gigabit wireless access in future cellular networks. In order to overcome
the propagation challenges, mmWave systems use a large number of antenna
elements both at the base station and at the user equipment, which lead to high
directivity gains, fully-directional communications, and possible noise-limited
operations. The fundamental differences between mmWave networks and traditional
ones challenge the classical design constraints, objectives, and available
degrees of freedom. This paper addresses the implications that highly
directional communication has on the design of an efficient medium access
control (MAC) layer. The paper discusses key MAC layer issues, such as
synchronization, random access, handover, channelization, interference
management, scheduling, and association. The paper provides an integrated view
on MAC layer issues for cellular networks, identifies new challenges and
tradeoffs, and provides novel insights and solution approaches.Comment: 21 pages, 9 figures, 2 tables, to appear in IEEE Transactions on
Communication
Understanding Noise and Interference Regimes in 5G Millimeter-Wave Cellular Networks
With the severe spectrum shortage in conventional cellular bands,
millimeter-wave (mmWave) frequencies have been attracting growing attention for
next-generation micro- and picocellular wireless networks. A fundamental and
open question is whether mmWave cellular networks are likely to be noise- or
interference-limited. Identifying in which regime a network is operating is
critical for the design of MAC and physical-layer procedures and to provide
insights on how transmissions across cells should be coordinated to cope with
interference. This work uses the latest measurement-based statistical channel
models to accurately assess the Interference-to-Noise Ratio (INR) in a wide
range of deployment scenarios. In addition to cell density, we also study
antenna array size and antenna patterns, whose effects are critical in the
mmWave regime. The channel models also account for blockage, line-of-sight and
non-line-of-sight regimes as well as local scattering, that significantly
affect the level of spatial isolation
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