Overview: A+B+C = VSAT

The benefits of VSAT systems and services are being realised in all spheres across the globe, both private and public. Banks, government departments, schools, hospitals, home offices, small enterprises, multi-national corporates, and rural telephony… all sectors are seizing upon the opportunity to get connected through satellite communications

Objective Measurement of Speech Quality in VoIP over Wireless LAN during Handoff

Quality of Service is a very important factor to determine the quality of a VoIP call. Different subjective and objective models exist for evaluating the speech quality in VoIP. E-model is one of the objective methods of measuring the speech quality; it considers various factors like packet loss, delay and codec impairments. The calculations of Emodel are not very accurate in case of handovers – when a VoIP call moves from one wireless LAN to another. This project conducted experimental evaluation of performance of E-model during handovers and proposes a new approach to accurately calculate the speech quality of VoIP during handovers. A detailed description of the experimental setup and the comparison of the new approach with E-model is presented in this report

Privacy Issues in Ubiquitous Multimedia Environments: Wake Sleeping Dogs, or Let Them Lie?

Many users are not aware of the potential privacy implications of ubiquitous multimedia applications. Decision-makers are often reluctant to raise users' awareness, since this may open a 'can of worms' and deter potential users. We conducted an opportunistic study after video-conferencing developers placed a camera in the common room of their university department, broadcasting the video on the Internet. The email debate following the common room users 'discovery' of the camera's existence was analysed as well as 47 anonymous questionnaire responses. Three distinct types of responses were identified, varying with the media type (audio vs. video) transmitted and scape of distribution (local vs. global). The groups also differ in their perception of the common room situation (public vs. private) and the degree of control exerted by observers and those observed. We conclude that privacy implications of ubiquitous multimedia applications must be made explicit. Users who discover privacy implication retrospectively are Likely to respond in an emotive manner, reject the technology, and lose trust in those responsible for it

Low Latency Low Loss Media Delivery Utilizing In-Network Packet Wash

This paper presents new techniques and mechanisms for carrying streams of layered video using Scalable Video Coding (SVC) from servers to clients, utilizing the Packet Wash mechanism which is part of the Big Packet Protocol (BPP). BPP was designed to handle the transfer of packets for high-bandwidth, low-latency applications, aiming to overcome a number of issues current networks have with high precision services. One of the most important advantages of BPP is that it allows the dynamic adaption of packets during transmission. BPP uses Packet Wash to reduce the payload, and the size of a packet by eliminating specific chunks. For video, this means cutting out specific segments of the transferred video, rather than dropping packets, as happens with UDP based transmission, or retrying the transmission of packets, as happens with TCP. The chunk elimination approach is well matched with SVC video, and these techniques and mechanisms are utilized and presented. An evaluation of the performance is provided, plus a comparison of using UDP or TCP, which are the other common approaches for carrying media over IP. Our main contributions are the mapping of SVC video into BPP packets to provide low latency, low loss delivery, which provides better QoE performance than either UDP or TCP, when using those techniques and mechanisms. This approach has proved to be an effective way to enhance the performance of video streaming applications, by obtaining continuous delivery, while maintaining guaranteed quality at the receiver. In this work we have successfully used an H264 SVC encoded video for layered video transmission utilizing BPP, and can demonstrate video delivery with low latency and low loss in limited bandwidth environments

Possibilities of QoS algorithms simulation and optimization

Tato bakalářská práce se zabývá problematikou řízení datových toků v konvergovaných sítích, které je implementováno za účelem poskytování telekomunikačních služeb v žádané kvalitě. Teoretická část práce nejprve poskytuje přehled měřitelných parametrů kvality služeb a uvádí faktory, kterými jsou ovlivněny. Dále rozebírá různé úrovně poskytovaných služeb a nakonec techniky používané pro zajištění QoS, tak jak jsou implementovány v síťových prostředcích. V praktické části je v simulačním softwaru Simulink zkonstruován model sítě s implementovaným řízením QoS. V této síti probíhá přenos několika datových toků s různými nároky na parametry provozu jako např. telefonie nebo přenos velkých souborů. Prostřednictvím grafického uživatelského rozhraní, vytvořeného v prostředí Matlab, lze měnit nastavení systému QoS v modelu a sledovat vliv na dosažené parametry probíhajících datových toků. Veškeré výsledky simulace jsou taktéž zobrazovány na uživatelském rozhraní. Uživatel má možnost buďto nastavit veškeré parametry ručně, nebo nechat program optimalizovat nastavení podle zadaného kritéria, např. ztrátovost paketů. Model tak demonstruje jaký vliv mají změny konfigurace QoS na kvalitu přenášených služeb. Celý model je zkonstruován tak, aby ho v případě dalšího využití bylo možné jednoduše překonfigurovat. Lze například přidat další datové toky nebo model pomocí předdefinovaných stavebních prvků rozšířit do rozlehlejší síťě.The bachelor's thesis deals with problematics of data transmission control in converged networks which is implemented there to offer telecommunication services in desired quality. Theoretical part of the thesis provides an overview of measurable parameters and lists factors by which they are affected. It discusses different levels of services offered and finally techniques used for it's provisioning as they are implemented in network appliances. In practical part a model of network with QoS implementation is constructed in simulation software Simulink. There are several traffic flows running in the simulated network which has different demands on transfer quality such as telephony or bulky file transfer. There is graphical user interface programmed in Matlab enviroment by which it is possible to alter QoS settings in the model and observe effect on achieved parameters of running data transfers. All simulation results are also displayed on the user interface. User may set all parameters manualy or let the software optimize settings according to prefered criterion, i.e. packet loss. In such way model demonstrates how changes in QoS configuratinon affects quality of services being transferred. The whole model is constructed in a way to be easily reconfigured in case of future use. It is possible for expample to add more traffic or to extend the model to larger network by using predefined blocks.

Quão virtuais somos?: o efeito da virtualização na confiança organizacional

Esta investigação estuda o efeito da virtualização na confiança interpessoal, intraorganizacional e interorganizacional. Participaram 202 colaboradores de diferentes empresas portuguesas. A informação foi obtida através de quatro instrumentos: (1) Questionário Grau de Virtualização; (2) Questionário Confiança Interorganizacional; (3) Questionário Confiança Intraorganizacional e, (4) Questionário Confiança Interpessoal. Para testar as nossas hipóteses recorreu-se a modelos de regressão linear múltipla e hierárquica verificando que existe um efeito do Grau de Virtualização sobre a Confiança Interpessoal e Intraorganizacional. Mas a Dimensão da Organização emergiu como fator moderador dos efeitos da virtualização na Confiança Interpessoal e Confiança Intraorganizacional. O estudo confirma o papel da virtualização em contexto de trabalho na dinâmica e construção de várias dimensões da confiança nas organizações; How Virtual are we? The effect of virtualization on organizational trust. Abstract: This research studies the effect of virtualization on Interpersonal, Intra-organizational and Inter-organizational trust. It counted with the participation of 202 employees from different Portuguese companies. The data was obtained from four tools: (1) Degree of Virtualization Survey; (2) Inter-organizational trust Survey; (3) Intra-organizational Survey and (4) Interpersonal Trust Survey. To test our hypothesis, multiple linear regression model and hierarchical models were applied, showing a connection between the Virtualization Degree and both Interpersonal and Intra-Orgazinational Trust. The Organization Dimension emerged as a moderating factor of the virtualization effects on Interpersonal and Intra-Orgazinational Trust. This study confirms the role that virtualization has in an work environment, either on the building and the dynamics of the several trust dimensions, in organizations

Assessing the quality of audio and video components in desktop multimedia conferencing

This thesis seeks to address the HCI (Human-Computer Interaction) research problem of how to establish the level of audio and video quality that end users require to successfully perform tasks via networked desktop videoconferencing. There are currently no established HCI methods of assessing the perceived quality of audio and video delivered in desktop videoconferencing. The transport of real-time speech and video information across new digital networks causes novel and different degradations, problems and issues to those common in the traditional telecommunications areas (telephone and television). Traditional assessment methods involve the use of very short test samples, are traditionally conducted outside a task-based environment, and focus on whether a degradation is noticed or not. But these methods cannot help establish what audio-visual quality is required by users to perform tasks successfully with the minimum of user cost, in interactive conferencing environments. This thesis addresses this research gap by investigating and developing a battery of assessment methods for networked videoconferencing, suitable for use in both field trials and laboratory-based studies. The development and use of these new methods helps identify the most critical variables (and levels of these variables) that affect perceived quality, and means by which network designers and HCI practitioners can address these problems are suggested. The output of the thesis therefore contributes both methodological (i.e. new rating scales and data-gathering methods) and substantive (i.e. explicit knowledge about quality requirements for certain tasks) knowledge to the HCI and networking research communities on the subjective quality requirements of real-time interaction in networked videoconferencing environments. Exploratory research is carried out through an interleaved series of field trials and controlled studies, advancing substantive and methodological knowledge in an incremental fashion. Initial studies use the ITU-recommended assessment methods, but these are found to be unsuitable for assessing networked speech and video quality for a number of reasons. Therefore later studies investigate and establish a novel polar rating scale, which can be used both as a static rating scale and as a dynamic continuous slider. These and further developments of the methods in future lab- based and real conferencing environments will enable subjective quality requirements and guidelines for different videoconferencing tasks to be established

Dynamic adaptation of streamed real-time E-learning videos over the internet

Even though the e-learning is becoming increasingly popular in the academic environment, the quality of synchronous e-learning video is still substandard and significant work needs to be done to improve it. The improvements have to be brought about taking into considerations both: the network requirements and the psycho- physical aspects of the human visual system. One of the problems of the synchronous e-learning video is that the head-and-shoulder video of the instructor is mostly transmitted. This video presentation can be made more interesting by transmitting shots from different angles and zooms. Unfortunately, the transmission of such multi-shot videos will increase packet delay, jitter and other artifacts caused by frequent changes of the scenes. To some extent these problems may be reduced by controlled reduction of the quality of video so as to minimise uncontrolled corruption of the stream. Hence, there is a need for controlled streaming of a multi-shot e-learning video in response to the changing availability of the bandwidth, while utilising the available bandwidth to the maximum. The quality of transmitted video can be improved by removing the redundant background data and utilising the available bandwidth for sending high-resolution foreground information. While a number of schemes exist to identify and remove the background from the foreground, very few studies exist on the identification and separation of the two based on the understanding of the human visual system. Research has been carried out to define foreground and background in the context of e-learning video on the basis of human psychology. The results have been utilised to propose methods for improving the transmission of e-learning videos. In order to transmit the video sequence efficiently this research proposes the use of Feed- Forward Controllers that dynamically characterise the ongoing scene and adjust the streaming of video based on the availability of the bandwidth. In order to satisfy a number of receivers connected by varied bandwidth links in a heterogeneous environment, the use of Multi-Layer Feed-Forward Controller has been researched. This controller dynamically characterises the complexity (number of Macroblocks per frame) of the ongoing video sequence and combines it with the knowledge of availability of the bandwidth to various receivers to divide the video sequence into layers in an optimal way before transmitting it into network. The Single-layer Feed-Forward Controller inputs the complexity (Spatial Information and Temporal Information) of the on-going video sequence along with the availability of bandwidth to a receiver and adjusts the resolution and frame rate of individual scenes to transmit the sequence optimised to give the most acceptable perceptual quality within the bandwidth constraints. The performance of the Feed-Forward Controllers have been evaluated under simulated conditions and have been found to effectively regulate the streaming of real-time e-learning videos in order to provide perceptually improved video quality within the constraints of the available bandwidth