289,061 research outputs found
SIP-based mobility management in next generation networks
The ITU-T definition of next generation networks includes the ability to make use of multiple broadband transport technologies and to support generalized mobility. Next generation networks must integrate several IP-based access technologies in a seamless way. In this article, we first describe the requirements of a mobility management scheme for multimedia real-time communication services; then, we report a survey of the mobility management schemes proposed in the recent literature to perform vertical handovers between heterogeneous networks. Based on this analysis, we propose an application-layer solution for mobility management that is based on the SIP protocol and satisfies the most important requirements for a proper implementation of vertical handovers. We also implemented our proposed solution, testing it in the field, and proving its overall feasibility and its interoperability with different terminals and SIP servers
Service Virtualisation of Internet-of-Things Devices: Techniques and Challenges
Service virtualization is an approach that uses virtualized environments to
automatically test enterprise services in production-like conditions. Many
techniques have been proposed to provide such a realistic environment for
enterprise services. The Internet-of-Things (IoT) is an emerging field which
connects a diverse set of devices over different transport layers, using a
variety of protocols. Provisioning a virtual testbed of IoT devices can
accelerate IoT application development by enabling automated testing without
requiring a continuous connection to the physical devices. One solution is to
expand existing enterprise service virtualization to IoT environments. There
are various structural differences between the two environments that should be
considered to implement appropriate service virtualization for IoT. This paper
examines the structural differences between various IoT protocols and
enterprise protocols and identifies key technical challenges that need to be
addressed to implement service virtualization in IoT environments.Comment: 4 page
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Technical Review of Residential Programmable Communicating Thermostat Implementation for Title 24-2008
From carbon nanotubes and silicate layers to graphene platelets for polymer nanocomposites
In spite of extensive studies conducted on carbon nanotubes and silicate layers for their polymer-based nanocomposites, the rise of graphene now provides a more promising candidate due to its exceptionally high mechanical performance and electrical and thermal conductivities. The present study developed a facile approach to fabricate epoxy–graphene nanocomposites by thermally expanding a commercial product followed by ultrasonication and solution-compounding with epoxy, and investigated their morphologies, mechanical properties, electrical conductivity and thermal mechanical behaviour. Graphene platelets (GnPs) of 3.5
Applying Formal Methods to Networking: Theory, Techniques and Applications
Despite its great importance, modern network infrastructure is remarkable for
the lack of rigor in its engineering. The Internet which began as a research
experiment was never designed to handle the users and applications it hosts
today. The lack of formalization of the Internet architecture meant limited
abstractions and modularity, especially for the control and management planes,
thus requiring for every new need a new protocol built from scratch. This led
to an unwieldy ossified Internet architecture resistant to any attempts at
formal verification, and an Internet culture where expediency and pragmatism
are favored over formal correctness. Fortunately, recent work in the space of
clean slate Internet design---especially, the software defined networking (SDN)
paradigm---offers the Internet community another chance to develop the right
kind of architecture and abstractions. This has also led to a great resurgence
in interest of applying formal methods to specification, verification, and
synthesis of networking protocols and applications. In this paper, we present a
self-contained tutorial of the formidable amount of work that has been done in
formal methods, and present a survey of its applications to networking.Comment: 30 pages, submitted to IEEE Communications Surveys and Tutorial
Probabilistic communication complexity over the reals
Deterministic and probabilistic communication protocols are introduced in
which parties can exchange the values of polynomials (rather than bits in the
usual setting). It is established a sharp lower bound on the communication
complexity of recognizing the -dimensional orthant, on the other hand the
probabilistic communication complexity of its recognizing does not exceed 4. A
polyhedron and a union of hyperplanes are constructed in \RR^{2n} for which a
lower bound on the probabilistic communication complexity of recognizing
each is proved. As a consequence this bound holds also for the EMPTINESS and
the KNAPSACK problems
Development of a first-contact protocol to guide assessment of adult patients in rehabilitation services networks
OBJECTIVE: This paper describes the development of the Protocol for Identification of Problems for Rehabilitation (PLPR), a tool to standardize collection of functional information based on the International Classification of Functioning, Disability and Health (ICF). DEVELOPMENT OF THE PROTOCOL: The PLPR was developed for use during the initial contact with adult patients within a public network of rehabilitation services. Steps to develop the protocol included: survey of the ICF codes most used by clinical professionals; compilation of data from functional instruments; development and pilot testing of a preliminary version in the service settings; discussion with professionals and development of the final version. The final version includes: user identification; social and health information; brief functional description (BFD); summary of the BFD; and PLPR results. Further testing of the final version will be conducted. CONCLUSIONS: The protocol standardizes the first contact between the user and the rehabilitation service. Systematic use of the protocol could also help to create a functional database that would allow comparisons between rehabilitation services and countries over time
ARRAY BASED FREE SPACE OPTIC SYSTEM FOR TACTICAL COMMUNICATIONS
Free-space optical (FSO) communications offer a resilient and flexible alternative communications medium to current radio technologies, which are increasingly threatened by our peer adversaries. FSO provides many advantages to radio technologies, including higher bandwidth capability and increased security through its low probability of detection (LPD) and low probability of interception (LPI) characteristics. However, current FSO systems are limited in range due to line-of-sight requirements and suffer loss from atmospheric attenuation.
This thesis proposes the use of arrayed optical emitters for FSO communication by developing a link-layer protocol that leverages the inherent error correction of quick response (QR) encoding to increase bandwidth and overcome atmospheric loss. Through the testing of a system built with commercial-off-the-shelf equipment and a survey of current optical transmitter and receiver technology, this link-layer protocol was validated and estimated to provide similar data rates to current single emitter FSO systems.
Various limitations were discovered in the current structure of the protocol. Future work should be conducted to correct inefficiencies in the QR encoding format when applied to a transmission medium. Additionally, technological advancements in hardware systems, including the large-scale production of VCSELs and faster high-speed cameras, must be achieved before such an FSO would be viable for large-scale use.http://archive.org/details/arraybasedfreesp1094559655Captain, United States Marine CorpsApproved for public release; distribution is unlimited
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