1,027 research outputs found
The Outage Probability of a Finite Ad Hoc Network in Nakagami Fading
An ad hoc network with a finite spatial extent and number of nodes or mobiles
is analyzed. The mobile locations may be drawn from any spatial distribution,
and interference-avoidance protocols or protection against physical collisions
among the mobiles may be modeled by placing an exclusion zone around each
radio. The channel model accounts for the path loss, Nakagami fading, and
shadowing of each received signal. The Nakagami m-parameter can vary among the
mobiles, taking any positive value for each of the interference signals and any
positive integer value for the desired signal. The analysis is governed by a
new exact expression for the outage probability, defined to be the probability
that the signal-to-interference-and-noise ratio (SINR) drops below a threshold,
and is conditioned on the network geometry and shadowing factors, which have
dynamics over much slower timescales than the fading. By averaging over many
network and shadowing realizations, the average outage probability and
transmission capacity are computed. Using the analysis, many aspects of the
network performance are illuminated. For example, one can determine the
influence of the choice of spreading factors, the effect of the receiver
location within the finite network region, and the impact of both the fading
parameters and the attenuation power laws.Comment: to appear in IEEE Transactions on Communication
Performance Analysis of Fifth-Generation Cellular Uplink
Fifth-generation cellular networks are expected to exhibit at least three
primary physical-layer differences relative to fourth-generation ones:
millimeter-wave propagation, antenna-array directionality, and densification of
base stations. In this paper, the effects of these differences on the
performance of single-carrier frequency-domain multiple-access uplink systems
with frequency hopping are assessed. A new analysis, which is much more
detailed than any other in the existing literature and accommodates actual
base-station topologies, captures the primary features of uplink
communications. Distance-dependent power-law, shadowing, and fading models
based on millimeter-wave measurements are introduced. The beneficial effects of
base-station densification, highly directional sectorization, and frequency
hopping are illustrated.Comment: 6 pages, 5 figures, IEEE Military Commun. Conf. (MILCOM), 201
A New Analysis of the DS-CDMA Cellular Uplink Under Spatial Constraints
A new analysis is presented for the direct-sequence code-division multiple
access (DS-CDMA) cellular uplink. For a given network topology, closed-form
expressions are found for the outage probability and rate of each uplink in the
presence of path-dependent Nakagami fading and log-normal shadowing. The
topology may be arbitrary or modeled by a random spatial distribution for a
fixed number of base stations and mobiles placed over a finite area with the
separations among them constrained to exceed a minimum distance. The analysis
is more detailed and accurate than existing ones and facilitates the resolution
of network design issues, including the influence of the minimum base-station
separation, the role of the spreading factor, and the impact of various
power-control and rate-control policies. It is shown that once power control is
established, the rate can be allocated according to a fixed-rate or
variable-rate policy with the objective of either meeting an outage constraint
or maximizing throughput. An advantage of the variable-rate policy is that it
allows an outage constraint to be enforced on every uplink, whereas the
fixed-rate policy can only meet an average outage constraint.Comment: 6 pages, 6 figures, to appear at International Conference on
Communications (ICC) 201
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