1,657 research outputs found
Ubiquitous Computing
The aim of this book is to give a treatment of the actively developed domain of Ubiquitous computing. Originally proposed by Mark D. Weiser, the concept of Ubiquitous computing enables a real-time global sensing, context-aware informational retrieval, multi-modal interaction with the user and enhanced visualization capabilities. In effect, Ubiquitous computing environments give extremely new and futuristic abilities to look at and interact with our habitat at any time and from anywhere. In that domain, researchers are confronted with many foundational, technological and engineering issues which were not known before. Detailed cross-disciplinary coverage of these issues is really needed today for further progress and widening of application range. This book collects twelve original works of researchers from eleven countries, which are clustered into four sections: Foundations, Security and Privacy, Integration and Middleware, Practical Applications
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
Walkabout : an asynchronous messaging architecture for mobile devices
Modern mobile devices are prolific producers and consumers of digital data, and wireless networking capabilities enable them to transfer their data over the Internet while moving. Applications running on these devices may perform transfers to upload data for backup or distribution, or to download new content on demand. Unfortunately, the limited connectivity that mobile devices experience can make these transfers slow and impractical as the amount of data increases. This thesis argues that asynchronous messaging supported by local proxies can improve the transfer capabilities of mobile devices, making it practical for them to participate in large Internet transfers. The design of the Walkabout architecture follows this approach: proxies form store-and-forward overlay networks to deliver messages asynchronously across the Internet on behalf of devices. A mobile device uploads a message to a local proxy at rapid speed, and the overlay delivers it to one or more destination devices, caching the message until each one is able to retrieve it from a local proxy. A device is able to partially upload or download a message whenever it has network connectivity, and can resume this transfer at any proxy if interrupted through disconnection. Simulation results show that Walkabout provides better throughput for mobile devices than is possible under existing methods, for a range of movement patterns. Upload and end-to-end to transfer speeds are always high when the device sending the message is mobile. In the basic Walkabout model, a message sent to a mobile device that is repeatedly moving between a small selection of connection points experiences high download and end-to-end transfer speeds, but these speeds fall as the number of connection points grows. Pre-emptive message delivery extensions improve this situation, making fast end-to-end transfers and device downloads possible under any pattern of movement. This thesis describes the design and evaluation of Walkabout, with both practical implementation and extensive simulation under real-world scenarios
Systems-Level Support for Mobile Device Connectivity.
The rise of handheld computing devices has
inspired a great deal of research aimed at
addressing the unique problems posed by their
mobile, "always-on" nature. In order to help
mobile devices navigate a complex world of
overlapping, uneven public wireless coverage, one
must be mindful of the distinction between
nomadic usage and true mobility. Accordingly,
systems research must move beyond simply
optimizing for a set of local conditions (e.g.,
finding the best access point for a laptop user
in a stationary location) to considering the
"derivative of connectivity" when network
conditions are constantly in flux.
This dissertation presents a new paradigm for
networking support on mobile devices. This
project has several complementary aspects. As
devices encounter network connectivity our system
both evaluates the application-level quality of
WiFi access points and updates a device-centric
mobility model. Together, this mobility model and
AP quality database yield "connectivity
forecasts," which let applications optimize not
just for current network conditions but for
the expected big picture to come. Results of a
prototype deployment in several cities shows that
considering the application-level quality of APs
(rather than just signal strength) significantly
boosts the success rate of finding a usable
access point. Furthermore, this dissertation
shows how connectivity forecasts---even with
minimal model training time---allow several
applications commonly found on mobile devices to
reap significant benefits, such as extended
battery life.
Mobile devices are often within range of multiple
connectivity options, however, and choosing just
one therefore ignores potential connectivity.
This dissertation describes a virtual link layer
for Linux, called Juggler, that uses one network
card to simultaneously associate with many WiFi
APs, ad hoc groups or mesh networks. The results
show how Juggler can boost effective bandwidth by
striping data across multiple APs, enable
seamless 802.11 handoff by preemptively
associating with the "next" AP before the
current one become unusable, and maintain a
modest side-channel to the user's personal area
network or mesh network without impacting
foreground bandwidth to infrastructure.Ph.D.Computer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/61718/1/tonynich_1.pd
A survey on cost-effective context-aware distribution of social data streams over energy-efficient data centres
Social media have emerged in the last decade as a viable and ubiquitous means of communication. The ease of user content generation within these platforms, e.g. check-in information, multimedia data, etc., along with the proliferation of Global Positioning System (GPS)-enabled, always-connected capture devices lead to data streams of unprecedented amount and a radical change in information sharing. Social data streams raise a variety of practical challenges, including derivation of real-time meaningful insights from effectively gathered social information, as well as a paradigm shift for content distribution with the leverage of contextual data associated with user preferences, geographical characteristics and devices in general. In this article we present a comprehensive survey that outlines the state-of-the-art situation and organizes challenges concerning social media streams and the infrastructure of the data centres supporting the efficient access to data streams in terms of content distribution, data diffusion, data replication, energy efficiency and network infrastructure. We systematize the existing literature and proceed to identify and analyse the main research points and industrial efforts in the area as far as modelling, simulation and performance evaluation are concerned
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