2,244 research outputs found
Spatial networks with wireless applications
Many networks have nodes located in physical space, with links more common
between closely spaced pairs of nodes. For example, the nodes could be wireless
devices and links communication channels in a wireless mesh network. We
describe recent work involving such networks, considering effects due to the
geometry (convex,non-convex, and fractal), node distribution,
distance-dependent link probability, mobility, directivity and interference.Comment: Review article- an amended version with a new title from the origina
Open-Loop Spatial Multiplexing and Diversity Communications in Ad Hoc Networks
This paper investigates the performance of open-loop multi-antenna
point-to-point links in ad hoc networks with slotted ALOHA medium access
control (MAC). We consider spatial multiplexing transmission with linear
maximum ratio combining and zero forcing receivers, as well as orthogonal space
time block coded transmission. New closed-form expressions are derived for the
outage probability, throughput and transmission capacity. Our results
demonstrate that both the best performing scheme and the optimum number of
transmit antennas depend on different network parameters, such as the node
intensity and the signal-to-interference-and-noise ratio operating value. We
then compare the performance to a network consisting of single-antenna devices
and an idealized fully centrally coordinated MAC. These results show that
multi-antenna schemes with a simple decentralized slotted ALOHA MAC can
outperform even idealized single-antenna networks in various practical
scenarios.Comment: 51 pages, 19 figures, submitted to IEEE Transactions on Information
Theor
Impact of Power Allocation and Antenna Directivity in the Capacity of a Multiuser Cognitive Ad Hoc Network
This paper studies the benefits that power control and antenna directivity can bring to the capacity of a multiuser cognitive radio network. The main objective is to optimize the secondary network sum rate under the capacity constraint of the primary network. Exploiting location awareness, antenna directivity, and the power control capability, the cognitive radio ad hoc network can broaden its coverage and improve capacity. Computer simulations show that by employing the proposed method the system performance is significantly enhanced compared to conventional fixed power allocation
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
The Role of the Internet of Things in Network Resilience
Disasters lead to devastating structural damage not only to buildings and
transport infrastructure, but also to other critical infrastructure, such as
the power grid and communication backbones. Following such an event, the
availability of minimal communication services is however crucial to allow
efficient and coordinated disaster response, to enable timely public
information, or to provide individuals in need with a default mechanism to post
emergency messages. The Internet of Things consists in the massive deployment
of heterogeneous devices, most of which battery-powered, and interconnected via
wireless network interfaces. Typical IoT communication architectures enables
such IoT devices to not only connect to the communication backbone (i.e. the
Internet) using an infrastructure-based wireless network paradigm, but also to
communicate with one another autonomously, without the help of any
infrastructure, using a spontaneous wireless network paradigm. In this paper,
we argue that the vast deployment of IoT-enabled devices could bring benefits
in terms of data network resilience in face of disaster. Leveraging their
spontaneous wireless networking capabilities, IoT devices could enable minimal
communication services (e.g. emergency micro-message delivery) while the
conventional communication infrastructure is out of service. We identify the
main challenges that must be addressed in order to realize this potential in
practice. These challenges concern various technical aspects, including
physical connectivity requirements, network protocol stack enhancements, data
traffic prioritization schemes, as well as social and political aspects
- …