807 research outputs found
Performance evaluation of VoIP technology in an extended service set, in concordance with IEEE 802.11g
O desempenho é avaliado experimentalmente com base nas métricas associadas à Qualidade de Serviço [QoS] e à Qualidade de Experiência do Usuário [QoE] no serviço de voz sobre IP [VoIP] para os codecs G.711 e G.729, em um conjunto de serviço estendido com tecnologia Wi-Fi, de acordo com o padrão IEEE 802.11g, implementado através de sistemas embarcados. As métricas de QoS são obtidas através da técnica intrusiva de injeção de tráfego, além disso, a QoE é avaliada por meio da análise MOSc (Mean Opinion Score conversational). Os melhores resultados foram obtidos pelo codec G.729, que atingiu até 25 fluxos simultâneos com valores ótimos de atraso, jitter e perda de pacotes de acordo com a recomendação ITU-T para VoIP. No entanto, o G.711 apresentou melhor throughput. Por outro lado, a avaliação da QoE indica uma ligeira superioridade do G.729 na avaliação MOSc. Finalmente, conclui-se que a perda de pacotes e o atraso são as métricas mais influentes na degradação do serviço VoIP.En este artículo se evalúa experimentalmente el desempeño en función de las métricas asociadas a Calidad de Servicio [QoS] y Calidad de Experiencia de Usuario [QoE] en el servicio de voz sobre IP [VoIP] para los códecs G.711 y G.729, sobre un set de servicio extendido con tecnología Wi-Fi, en concordancia con el estándar IEEE 802.11g, implementado mediante sistemas embebidos. Las métricas de QoS se obtienen mediante la técnica intrusiva de inyección de tráfico, adicionalmente se evalúa la QoE por medio del análisis MOSc [Mean Opinion Score conversational). Los mejores resultados fueron obtenidos por el códec G.729, que alcanzó hasta 25 flujos concurrentes con valores óptimos de retardo, jitter y pérdida de paquetes según la recomendación de la ITU-T para VoIP. Sin embargo, G.711 presentó un mejor throughput. Por otro lado, la evaluación de QoE señala una ligera superioridad de G.729 en la valoración MOSc. Finalmente, se concluye que la pérdida de paquetes y el retardo son las métricas más influyentes en la degradación del servicio de VoIP.In this paper, we evaluate the performance in function of the metrics associated to Quality of Service [QoS] and Quality of user Experience [QoE] in an experimental way in the VoIP service for G.711 and G.729 códecs. This was performed over an extended service set based on Wi-Fi technology in concordance with IEEE 802.11g standard using embedded systems. QoS related metrics are obtained by using the intrusive traffic injection technique. In addition, we assessed the QoE using the MOSc [Mean Opinion Score conversational] analysis. The best results were obtained for G.729, reaching up to 25 simultaneous injections with optimal delay, jitter and packet loss values according to the ITU-T recommendation for VoIP. However, the G.711 codec presented a better throughput. On the other hand, QoE evaluation indicates a slight superiority of G.729 in the MOSc appreciation. Finally, we conclude that packet loss and delay are the most influential metrics in VoIP service degradation
Deploying rural community wireless mesh networks
Inadequate Internet access is widening the digital divide between town and countryside, degrading both social communication and business advancements in rural areas. Wireless mesh networking can provide an excellent framework
for delivering broadband services to such areas. With this in mind, Lancaster University deployed a WMN in the rural village of Wray over a three-year period, providing the community with Internet service that exceeds many urban offerings. The project gave researchers a real-world testbed for exploring the technical and social issues entailed in deploying WMNs in the heart of a small community
VoIP over WLAN: What about the Presence of Radio Interference?
In this chapter, the performance of VoIP over WLAN is analyzed under the effect of physical
layer interference, in the presence and absence of cross-traffic. The goal is twofold: first to
underline the importance of radio interference in the behavior of a WLAN when supporting
VoIP applications; second to outline solutions to avoid interference and thus optimizing a VoIP
call over aWLAN. To this aim, an experimental approach based on cross-layermeasurements
is adopted, describing and commenting meaningful results
obtained from a number of experiments conducted by the authors on a testbed operating
in a semi-anechoic chamber and emulating two typical real life scenarios
Software defined wireless network (sdwn) for industrial environment: case of underground mine
Avec le développement continu des industries minières canadiennes, l’établissement des réseaux de communications souterrains avancés et sans fil est devenu un élément essentiel du processus industriel minier et ceci pour améliorer la productivité et assurer la communication entre les mineurs. Cette étude vise à proposer un système de communication minier en procurant une architecture SDWN (Software Defined Wireless Network) basée sur la technologie de communication LTE. Dans cette étude, les plateformes les plus importantes de réseau mobile 4G ont été étudiées, configurées et testées dans deux zones différentes : un tunnel de mine souterrain et un couloir intérieur étroit. Également, une architecture mobile combinant SDWN et NFV (Network Functions Virtualization) a été réalisée
ACUTA Journal of Telecommunications in Higher Education
In This Issue
To VolP or Not to VolP
Preparing Your Campus for a VolP Conversion
Strategic Planning in the College and University Ecosystem: The Common Denominators
Advertorial:
Going Wireless at Fiber Speeds
Open-Source VolP for Colleges and Universities
Institutional Excellence Award Honorable Mention The Naval Postgraduate School
Interview
President\u27s Message
From the Executive Director
Here\u27s My Advic
ACUTA Journal of Telecommunications in Higher Education
In This Issue
Wireless Outlook 2012
802.11n Wireless in the Enterprise- The Next Big Change
The University of Tulsa: A Wireless Campus
Advertorial: Deploying Media Switching Systems for Educational lnstitutions
Faster Wireless LAN Connections May Help Support Voice & Video Traffic
Wireless at Syracuse
Expectation Versus Experience: The Realities of Life on the Wireless Road
lnstitutional Excellence Award Honorable Mention UC Mobile
Interview
President\u27s Message
From the Executive Directo
Improving the Performance of Wireless LANs
This book quantifies the key factors of WLAN performance and describes methods for improvement. It provides theoretical background and empirical results for the optimum planning and deployment of indoor WLAN systems, explaining the fundamentals while supplying guidelines for design, modeling, and performance evaluation. It discusses environmental effects on WLAN systems, protocol redesign for routing and MAC, and traffic distribution; examines emerging and future network technologies; and includes radio propagation and site measurements, simulations for various network design scenarios, numerous illustrations, practical examples, and learning aids
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