42,513 research outputs found
Fundamental Limits of Wideband Localization - Part II: Cooperative Networks
The availability of positional information is of great importance in many
commercial, governmental, and military applications. Localization is commonly
accomplished through the use of radio communication between mobile devices
(agents) and fixed infrastructure (anchors). However, precise determination of
agent positions is a challenging task, especially in harsh environments due to
radio blockage or limited anchor deployment. In these situations, cooperation
among agents can significantly improve localization accuracy and reduce
localization outage probabilities. A general framework of analyzing the
fundamental limits of wideband localization has been developed in Part I of the
paper. Here, we build on this framework and establish the fundamental limits of
wideband cooperative location-aware networks. Our analysis is based on the
waveforms received at the nodes, in conjunction with Fisher information
inequality. We provide a geometrical interpretation of equivalent Fisher
information for cooperative networks. This approach allows us to succinctly
derive fundamental performance limits and their scaling behaviors, and to treat
anchors and agents in a unified way from the perspective of localization
accuracy. Our results yield important insights into how and when cooperation is
beneficial.Comment: To appear in IEEE Transactions on Information Theor
Thirty Years of Machine Learning: The Road to Pareto-Optimal Wireless Networks
Future wireless networks have a substantial potential in terms of supporting
a broad range of complex compelling applications both in military and civilian
fields, where the users are able to enjoy high-rate, low-latency, low-cost and
reliable information services. Achieving this ambitious goal requires new radio
techniques for adaptive learning and intelligent decision making because of the
complex heterogeneous nature of the network structures and wireless services.
Machine learning (ML) algorithms have great success in supporting big data
analytics, efficient parameter estimation and interactive decision making.
Hence, in this article, we review the thirty-year history of ML by elaborating
on supervised learning, unsupervised learning, reinforcement learning and deep
learning. Furthermore, we investigate their employment in the compelling
applications of wireless networks, including heterogeneous networks (HetNets),
cognitive radios (CR), Internet of things (IoT), machine to machine networks
(M2M), and so on. This article aims for assisting the readers in clarifying the
motivation and methodology of the various ML algorithms, so as to invoke them
for hitherto unexplored services as well as scenarios of future wireless
networks.Comment: 46 pages, 22 fig
Coverage Protocols for Wireless Sensor Networks: Review and Future Directions
The coverage problem in wireless sensor networks (WSNs) can be generally
defined as a measure of how effectively a network field is monitored by its
sensor nodes. This problem has attracted a lot of interest over the years and
as a result, many coverage protocols were proposed. In this survey, we first
propose a taxonomy for classifying coverage protocols in WSNs. Then, we
classify the coverage protocols into three categories (i.e. coverage aware
deployment protocols, sleep scheduling protocols for flat networks, and
cluster-based sleep scheduling protocols) based on the network stage where the
coverage is optimized. For each category, relevant protocols are thoroughly
reviewed and classified based on the adopted coverage techniques. Finally, we
discuss open issues (and recommend future directions to resolve them)
associated with the design of realistic coverage protocols. Issues such as
realistic sensing models, realistic energy consumption models, realistic
connectivity models and sensor localization are covered
Prospects for joint observations of gravitational waves and gamma rays from merging neutron star binaries
The detection of the events GW150914 and GW151226, both consistent with the
merger of a binary black hole system (BBH), opened the era of gravitational
wave (GW) astronomy. Besides BBHs, the most promising GW sources are the
coalescences of binary systems formed by two neutron stars or a neutron star
and a black hole. These mergers are thought to be connected with short Gamma
Ray Bursts (GRBs), therefore combined observations of GW and electromagnetic
(EM) signals could definitively probe this association. We present a detailed
study on the expectations for joint GW and high-energy EM observations of
coalescences of binary systems of neutron stars with Advanced Virgo and LIGO
and with the \emph{Fermi} gamma-ray telescope. To this scope, we designed a
dedicated Montecarlo simulation pipeline for the multimessenger emission and
detection by GW and gamma-ray instruments, considering the evolution of the GW
detector sensitivities. We show that the expected rate of joint detection is
low during the Advanced Virgo and Advanced LIGO 2016-2017 run; however, as the
interferometers approach their final design sensitivities, the rate will
increase by a factor of ten. Future joint observations will help to
constrain the association between short GRBs and binary systems and to solve
the puzzle of the progenitors of GWs. Comparison of the joint detection rate
with the ones predicted in this paper will help to constrain the geometry of
the GRB jet.Comment: 24 pages, 4 figure
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