6 research outputs found

    A MODEL FOR PREDICTING THE PERFORMANCE OF IP VIDEOCONFERENCING

    Get PDF
    With the incorporation of free desktop videoconferencing (DVC) software on the majority of the world's PCs, over the recent years, there has, inevitably, been considerable interest in using DVC over the Internet. The growing popularity of DVC increases the need for multimedia quality assessment. However, the task of predicting the perceived multimedia quality over the Internet Protocol (IP) networks is complicated by the fact that the audio and video streams are susceptible to unique impairments due to the unpredictable nature of IP networks, different types of task scenarios, different levels of complexity, and other related factors. To date, a standard consensus to define the IP media Quality of Service (QoS) has yet to be implemented. The thesis addresses this problem by investigating a new approach to assess the quality of audio, video, and audiovisual overall as perceived in low cost DVC systems. The main aim of the thesis is to investigate current methods used to assess the perceived IP media quality, and then propose a model which will predict the quality of audiovisual experience from prevailing network parameters. This thesis investigates the effects of various traffic conditions, such as, packet loss, jitter, and delay and other factors that may influence end user acceptance, when low cost DVC is used over the Internet. It also investigates the interaction effects between the audio and video media, and the issues involving the lip sychronisation error. The thesis provides the empirical evidence that the subjective mean opinion score (MOS) of the perceived multimedia quality is unaffected by lip synchronisation error in low cost DVC systems. The data-gathering approach that is advocated in this thesis involves both field and laboratory trials to enable the comparisons of results between classroom-based experiments and real-world environments to be made, and to provide actual real-world confirmation of the bench tests. The subjective test method was employed since it has been proven to be more robust and suitable for the research studies, as compared to objective testing techniques. The MOS results, and the number of observations obtained, have enabled a set of criteria to be established that can be used to determine the acceptable QoS for given network conditions and task scenarios. Based upon these comprehensive findings, the final contribution of the thesis is the proposal of a new adaptive architecture method that is intended to enable the performance of IP based DVC of a particular session to be predicted for a given network condition

    Technology 2002: The Third National Technology Transfer Conference and Exposition, volume 2

    Get PDF
    Proceedings from symposia of the Technology 2002 Conference and Exposition, December 1-3, 1992, Baltimore, MD. Volume 2 features 60 papers presented during 30 concurrent sessions

    Air Traffic Management Abbreviation Compendium

    Get PDF
    As in all fields of work, an unmanageable number of abbreviations are used today in aviation for terms, definitions, commands, standards and technical descriptions. This applies in general to the areas of aeronautical communication, navigation and surveillance, cockpit and air traffic control working positions, passenger and cargo transport, and all other areas of flight planning, organization and guidance. In addition, many abbreviations are used more than once or have different meanings in different languages. In order to obtain an overview of the most common abbreviations used in air traffic management, organizations like EUROCONTROL, FAA, DWD and DLR have published lists of abbreviations in the past, which have also been enclosed in this document. In addition, abbreviations from some larger international projects related to aviation have been included to provide users with a directory as complete as possible. This means that the second edition of the Air Traffic Management Abbreviation Compendium includes now around 16,500 abbreviations and acronyms from the field of aviation

    Storia delle telecomunicazioni

    Get PDF
    Focusing on the history of scientific and technological development over recent centuries, the book is dedicated to the history of telecommunications, where Italy has always been in the vanguard, and is presented by many of the protagonists of the last half century. The book is divided into five sections. The first, dealing with the origins, starts from the scientific bases of the evolution of telecommunications in the nineteenth century (Bucci), addressing the developments of scientific thought that led to the revolution of the theory of fields (Morando), analysing the birth of the three fundamental forms of communication – telegraph (Maggi), telephone (Del Re) and radio (Falciasecca) – and ending with the contribution made by the Italian Navy to the development of telecommunications (Carulli, Pelosi, Selleri, Tiberio). The second section, on technical and scientific developments, presents the numerical processing of signals (Rocca), illustrating the genesis and metamorphosis of transmission (Pupolin, Benedetto, Mengali, Someda, Vannucchi), network packets (Marsan, Guadagni, Lenzini), photonics in telecommunications (Prati) and addresses the issue of research within the institutions (Fedi-Morello), dwelling in particular on the CSELT (Mossotto). The next section deals with the sectors of application, offering an overview of radio, television and the birth of digital cinema (Vannucchi, Visintin), military communications (Maestrini, Costamagna), the development of radar (Galati) and spatial telecommunications (Tartara, Marconicchio). Section four, on the organisation of the services and the role of industry, outlines the rise and fall of the telecommunications industries in Italy (Randi), dealing with the telecommunications infrastructures (Caroppo, Gamerro), the role of the providers in national communications (Gerarduzzi), the networks and the mobile and wireless services (Falciasecca, Ongaro) and finally taking a look towards the future from the perspective of the last fifty years (Vannucchi). The last section, dealing with training and dissemination, offers an array of food for thought: university training in telecommunications, with focus on the evolution of legislation and on the professional profiles (Roveri), social and cultural aspects (Longo and Crespellani) as well as a glance over the most important museums, collections and documentary sources for telecommunications in Italy (Lucci, Savini, Temporelli, Valotti). The book is designed to offer a compendium comprising different analytical approaches, and aims to foster an interest in technology in the new generations, in the hope of stimulating potentially innovative research

    XXIII Congreso Argentino de Ciencias de la Computación - CACIC 2017 : Libro de actas

    Get PDF
    Trabajos presentados en el XXIII Congreso Argentino de Ciencias de la Computación (CACIC), celebrado en la ciudad de La Plata los días 9 al 13 de octubre de 2017, organizado por la Red de Universidades con Carreras en Informática (RedUNCI) y la Facultad de Informática de la Universidad Nacional de La Plata (UNLP).Red de Universidades con Carreras en Informática (RedUNCI

    CACIC 2015 : XXI Congreso Argentino de Ciencias de la Computación. Libro de actas

    Get PDF
    Actas del XXI Congreso Argentino de Ciencias de la Computación (CACIC 2015), realizado en Sede UNNOBA Junín, del 5 al 9 de octubre de 2015.Red de Universidades con Carreras en Informática (RedUNCI
    corecore