5,767 research outputs found

    Optimized Adaptive Streaming Representations based on System Dynamics

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    Adaptive streaming addresses the increasing and heterogenous demand of multimedia content over the Internet by offering several encoded versions for each video sequence. Each version (or representation) has a different resolution and bit rate, aimed at a specific set of users, like TV or mobile phone clients. While most existing works on adaptive streaming deal with effective playout-control strategies at the client side, we take in this paper a providers' perspective and propose solutions to improve user satisfaction by optimizing the encoding rates of the video sequences. We formulate an integer linear program that maximizes users' average satisfaction, taking into account the network dynamics, the video content information, and the user population characteristics. The solution of the optimization is a set of encoding parameters that permit to create different streams to robustly satisfy users' requests over time. We simulate multiple adaptive streaming sessions characterized by realistic network connections models, where the proposed solution outperforms commonly used vendor recommendations, in terms of user satisfaction but also in terms of fairness and outage probability. The simulation results further show that video content information as well as network constraints and users' statistics play a crucial role in selecting proper encoding parameters to provide fairness a mong users and to reduce network resource usage. We finally propose a few practical guidelines that can be used to choose the encoding parameters based on the user base characteristics, the network capacity and the type of video content

    Technology requirements for communication satellites in the 1980's

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    The key technology requirements are defined for meeting the forecasted demands for communication satellite services in the 1985 to 1995 time frame. Evaluation is made of needs for services and technical and functional requirements for providing services. The future growth capabilities of the terrestrial telephone network, cable television, and satellite networks are forecasted. The impact of spacecraft technology and booster performance and costs upon communication satellite costs are analyzed. Systems analysis techniques are used to determine functional requirements and the sensitivities of technology improvements for reducing the costs of meeting requirements. Recommended development plans and funding levels are presented, as well as the possible cost saving for communications satellites in the post 1985 era

    Integration of Interactive Voice Response Unit and Outage Management System

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    This project provides a technical solution that integrates the Interactive Voice Response Unit (IVR) and the Outage Management System (OMS) for the Public Service Company. The IVR system is introduced because its automatic call logging functionality can process a large volume of phone calls from the customers reporting electrical service problems. This is a major improvement over the current Trouble Call Center (TCC) infrastructure that has a limited number of agents handling a relatively small number of customer calls. Because OMS can receive more calls, it then can predict the outage locations and causes more accurately, dispatch more repair crews on time, and restore outages quicker. As a result, the company benefits greatly on its customer relationship and revenue generation. The goal of this project is to provide a simpler and less costly approach to the integration of IVR and OMS than the conventional integration approach provided by the IVR vender. The proposed solution utilizes the existing interface application between TCC and OMS. An adapter will be developed to communicate between IVR and the TCC-OMS interface. The adapter consists of a set of database tables and stored procedures. Compared with the vender\u27s full integration approach from IVR to OMS, this proposed simple solution provides significant savings on the cost and time of the interface development as well as the system maintenance and upgrade

    Performance Comparison of Dual Connectivity and Hard Handover for LTE-5G Tight Integration in mmWave Cellular Networks

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    MmWave communications are expected to play a major role in the Fifth generation of mobile networks. They offer a potential multi-gigabit throughput and an ultra-low radio latency, but at the same time suffer from high isotropic pathloss, and a coverage area much smaller than the one of LTE macrocells. In order to address these issues, highly directional beamforming and a very high-density deployment of mmWave base stations were proposed. This Thesis aims to improve the reliability and performance of the 5G network by studying its tight and seamless integration with the current LTE cellular network. In particular, the LTE base stations can provide a coverage layer for 5G mobile terminals, because they operate on microWave frequencies, which are less sensitive to blockage and have a lower pathloss. This document is a copy of the Master's Thesis carried out by Mr. Michele Polese under the supervision of Dr. Marco Mezzavilla and Prof. Michele Zorzi. It will propose an LTE-5G tight integration architecture, based on mobile terminals' dual connectivity to LTE and 5G radio access networks, and will evaluate which are the new network procedures that will be needed to support it. Moreover, this new architecture will be implemented in the ns-3 simulator, and a thorough simulation campaign will be conducted in order to evaluate its performance, with respect to the baseline of handover between LTE and 5G.Comment: Master's Thesis carried out by Mr. Michele Polese under the supervision of Dr. Marco Mezzavilla and Prof. Michele Zorz

    Dependent Failures And Failure Propagation In Electric Power Systems

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    Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2013Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2013Biz toplam kesinti sayısı dağılımını, cascading sürecinden sonra dallanma yöntemi ve yayılma ortalamasına göre tahmin ettikAn initial number of lines outaged can lead to a cascading propagation of further outages. We estimate the amount by which line outages propagate from standard utility data that is reported to TEİAŞ. We estimate the distribution of the total number of outages after cascading from the amount of propagation and a probabilistic branching process model of the cascading.Yüksek LisansM.Sc

    The 30/20 GHz flight experiment system, phase 2. Volume 1: Executive summary

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    Summary information on the final communication system design, communication payload, space vehicle, and development plan for the 30/20 GHz flight experiment will be installed on the LEASAT spacecraft which will be placed into orbit from the space shuttle cargo bay. The communication concept has two parts: a truck service and a customer premise service (CPS). The trucking system serves four spot beams which are interconnected in a satellite switched time division multiple access mode by an IF switch matrix. The CPS covers two large areas of the eastern United States with a pair of scanning beams

    Surveys of facilities for the potential effects from the fallout of airborne graphite fibers

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    The impact of the entry of graphite fibers into workplaces in the United States is discussed. Areas where an electrical failure could cause major problems include process and production systems, hospitals, and police/fire emergency communication systems
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