Strategic Project - UI 524 - 2014

Funder

Organizational Unit

Publications

Investigações de Desempenho de Ligações Laboratoriais IEEE 802.11 A

Publication . Carvalho, José Pacheco De; Veiga, Hugo; Pacheco, Cláudia Ribeiro; Reis, António

A importância das comunicações sem fios, utilizando dispositivos electrónicos, tem sido mundialmente reconhecida. O desempenho é de importância fundamental, resultando em comunicações mais fiáveis e eficientes. A segurança é também crucial. São apresentadas medidas em laboratório sobre vários aspectos de desempenho de ligações Wi-Fi IEEE 802.11 a, 54 Mbps com encriptação WPA2 e topologias ponto-a-ponto e ponto-multiponto. O nosso estudo contribui para avaliação do desempenho desta tecnologia sob encriptação WPA2, usando equipamentos disponíveis (pontos de acesso HP V-M200 e adaptadores Linksys WPC600N). São apresentados novos resultados de experiências TCP e UDP, sobre throughput TCP em função do tamanho do pacote TCP, bem como jitter e percentagem de perda de datagramas em função do tamanho do datagrama UDP. São feitas comparações com resultados correspondentes de ligações Abertas. São obtidas conclusões, em particular sobre o desempenho comparativo das ligações.

2021Conference object

Open access

Surface Analysis of Thick Targets by Nuclear Techniques

Publication . Carvalho, José Pacheco De; Pacheco, Cláudia Ribeiro; Reis, António

This article is about computer simulation for surface analysis through nuclear techniques, which are non-destructive. The energy analysis method is used. Energy spectra are computer simulated and compared to experimental data, giving sample composition and concentration profiles. The method is successfully applied to depth profiling of 12C nuclei in a thick target, using the 12C(d,p0)13C deuteron induced reaction. Elastic scattering permitted depth profiling of Al and O in a thick target. Scanning electron microscopy is used as a complementary technique, to give information about surface topography.

2022Conference object

Open access

Performance Studies Of IEEE 802.11 AC Laboratory Links

Publication . Carvalho, José Pacheco De; Veiga, Hugo; Pacheco, Cláudia Ribeiro; Reis, António

Wireless communications, involving electronic devices, have been increasingly important in society. Performance is a fundamental issue, resulting in more reliable and efficient communications. Security is also essential. Laboratory measurements are presented about several performance aspects of Wi-Fi IEEE 802.11ac WPA2 point-to-point links. Our study contributes to performance evaluation of this technology under WPA2 encryption, using new available equipments (Cisco 2702i access points and Edimax USB 3.0 AC 1200 adapters adapters). New results are given from TCP and UDP experiments concerning TCP throughput versus TCP packet size, jitter and percentage datagram loss versus UDP datagram size. Comparisons are made to results obtained for other IEEE 802.11 technologies. Conclusions are drawn about the comparative performance of the links.

2022Conference object

Open access

Extended Performance Research on IEEE 802.11a WPA2 Multi-Node Laboratory Links

Publication . Carvalho, Jose Pacheco De; Veiga, Hugo; Pacheco, Cláudia Ribeiro

Wireless communications, involving electronicdevices, are increasingly important. Performance is a fundamental issue, leading to more reliable and efficient communications. Security is also, no doubt, most important. Laboratory measurements were achieved about several performance aspects of Wi-Fi IEEE 802.11a 54 Mbps WPA2 links. Our study enriches performance evaluation of this technology, using accessible equipments (HP V-M200 access points and Linksys WPC600N adapters). New accurate results are given, namely at OSI level 4, from TCP and UDP experiments. TCP throughput is measured against TCP packet length. Jitter and percentage datagram loss are evaluated versus UDP datagram size. Results are examined for point-to-point, point-to-multipoint and four-node point-to-multipoint links. Comparisons are also made mainly to related data obtained for Open links. Conclusions are extracted about performance of the links.

2020Journal article

Restricted access

Extended Performance Research on IEEE 802.11 a WPA Multi-node Laboratory Links

Publication . Carvalho, José Pacheco De; Veiga, Hugo; Pacheco, Cláudia Ribeiro; Reis, António

Wireless communications, involving electronic devices, are increasingly important. Performance is a fundamental issue, leading to more reliable and efficient communications. Security is also, no doubt, most important. Laboratory measurements were achieved about several performance aspects of Wi-Fi IEEE 802.11a 54 MbpsWPA links. Our study enriches performance evaluation of this technology, using accessible equipment (HP V-M200 access points and Linksys WPC600N adapters). New accurate results are given, namely at OSI level 4, from TCP and UDP experiments. TCP throughput is measured against TCP packet length. Jitter and percentage datagram loss are evaluated versus UDP datagram size. Results are examined for point-to-point, point-to-multipoint and four-node point-to-multipoint links. Comparisons are also made mainly to related data obtained for Open links. Conclusions are extracted about performance of the links.

2021Book part

Restricted access