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Publicações

Publicações por CTM

2000

Mixed-signal BIST using correlation and reconfigurable hardware

Autores
Machado Da Silva, J; Duarte, JS; Matos, JS;

Publicação
Proceedings -Design, Automation and Test in Europe, DATE

Abstract
Reducing the area overhead required by BIST structures can be achieved by reconfiguring existing hardware to perform test related control and processing functions. This work shows how the resources required for these operations can be implemented in-circuit, taking advantage of programmable logic available in the system. Structural and functional tests are performed using correlation to obtain iDD and uOUT cross-correlation signatures, and to measure gain, phase, and total harmonic distortion. © 2000 IEEE.

2000

A novel approach to ARQ error control mechanisms for wireless LANs communications

Autores
Almeida, NT; Abrantes, SA;

Publicação
25TH ANNUAL IEEE CONFERENCE ON LOCAL COMPUTER NETWORKS - PROCEEDINGS

Abstract
Communications in high-speed wireless mobile networks have to deal with large varying transmission and service requirement conditions, often needing complex radio modulatians and concatenated error control functions. For the latter, it is usual to implement Forward Error Correction and Automatic Repeat reQuest (ARQ) mechanisms in, respectively, the Physical (PHY) and the Data Link Control (DLC) layers. Even so, the communication requirements of medium/high quality real-time services may be hard to meet under hostile transmission conditions. In this paper an analysis on some improvements over current ARQ error control schemes is presented, envisaging more efficient communications in high-speed wireless LANs. It will be shown that high performance ARQ schemes can be used at the DLC layer of wireless LANs by carrying critical control information in more robust physical modes. performance comparisons for current and proposed ARQ schemes, and some protocol implementation aspects, are the main focuses of analysis.

2000

Experiments with dynamic multiplexing and UPC renegotiation for video over ATM

Autores
Andrade, MT; Alves, AP;

Publicação
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

Abstract
In this paper we present an experimental approach for QoS-aware and bandwidth-efficient transmission of multimedia sources over ATM networks. VBR video sources are statistically multiplexed at the application level and the UPC parameters of a single connection for the aggregate traffic are dynamically renegotiated with the network during the session lifetime. A statistical multiplexer computes the required bandwidth for the aggregate traffic and dynamically assigns bandwidth according to the performances requested and network resources availability. A dynamic UPC manager using feedback information sent by the network, may initiate a renegotiation of traffic parameters upon receiving a request from the statistical multiplexer. Performing the connection admission control procedures for the aggregate traffic, allows significant reductions in the value of the total peak rate when compared to the sum of peak rates of individual connections. It also reduces the burstiness of the flow submitted to the network, thus increasing the lifetime of each set of UPC parameters. © Springer-Verlag Berlin Heidelberg 2000.

2000

Experiments with dynamic multiplexing and UPC renegotiation for video over ATM

Autores
Andrade, MT; Alves, AP;

Publicação
NETWORKING 2000

Abstract
In this paper we present an experimental approach for QoS-aware and bandwidth-efficient transmission of multimedia sources over ATM networks. VER video sources are statistically multiplexed at the application level and the UPC parameters of a single connection for the aggregate traffic are dynamically renegotiated with the network during the session lifetime, A statistical multiplexer computes the required bandwidth for the aggregate traffic and dynamically assigns bandwidth according to the performances requested and network resources availability. A dynamic UPC manager using feedback information sent by the network, may initiate a renegotiation of traffic parameters upon receiving a request from the statistical multiplexer. Performing the connection admission control procedures for the aggregate traffic, allows significant reductions in the value of the total peak rate when compared to the sum of peak rates of individual connections. It also reduces the burstiness of the flow submitted to the network, thus increasing the lifetime of each set of UPC parameters.

2000

<title>Case study on the use of agent technology for the management of networked multimedia systems</title>

Autores
Viana, P; Alves, AP;

Publicação
Internet Multimedia Management Systems

Abstract

2000

A case study on the use of agent technology for the management of networked multimedia systems

Autores
Viana, P; Alves, AP;

Publicação
INTERNET MULTIMEDIA MANAGEMENT SYSTEMS

Abstract
The evolution of Television towards de digital domain is opening new opportunities but also new challenges both to users and system managers. Audiovisual television archives will be an essential component of the whole digital television operators systems, as archived information needs to be available to a wide range of users. This paper presents the work developed at INESC Porto within the VIDION project and the experiments on merging television, computer and telecommunications concepts and technologies by the use of software agents and CORBA to assist in solving problems of information and system configuration and management in a TV archive. Aspects such as definition of the problem, architecture proposed and current state of the work will be the focus of the paper.

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