Avaliação do desempenho de novos serviços em redes IP

Mestrado em Engenharia Electrónica e TelecomunicaçõesOs benefícios económicos de fornecer múltiplos serviços numa única rede têm despertado grande interesse na introdução dos serviços VoIP e IPTV na internet. No entanto, estes serviços possuem requisitos rigorosos de qualidade de serviço, que a internet não está preparada para fornecer. Esta dissertação possui dois objectivos principais: O primeiro consiste em testar o comportamento dos serviços de IPTV e VoIP nas tecnologias IP existentes como Ethernet, IEEE 802.11 e ADSL quando expostas a diferentes condições de carga. Pretende-se também identificar os efeitos nos serviços de VoIP e IPTV de outros serviços como FTP, correio electrónico e HTTP. Foi utilizado OpNet um simulador de redes bastante popular ao no ambiente académico. Os resultados das simulações fornecem orientações importantes sobre a capacidade máxima de cada tecnologia tendo em conta os requisitos de qualidade de serviço; por outro lado identificam os serviços mais destrutivos para IPTV e VoIP. O segundo objectivo é a implementação de um modelo que permite a monitorização dos serviços de VoIP e IPTV, analisa os indicadores de desempenho reunidos e grava esses indicadores numa base de dados. Todo este processo será efectuado em tempo real com o objectivo de manter a base de dados actualizada. Os resultados disponibilizados por esta estrutura permitem uma melhor gestão da rede, os prestadores de serviços podem ter informações actualizadas sobre o desempenho dos seus serviços, consequentemente é possível identificar uma falha ou uma tendência futura. ABSTRACT: The economical benefits of providing multiple services over a single network infrastructure have spawned great interest in the introduction of new services, such VoIP and IPTV, in the Internet. However, these services have stringent Quality of Service requirements that the Internet was not designed to meet. This dissertation has two main objectives: The first objective is to test the behavior of IPTV and VoIP services in the existing IP network technologies such as Ethernet, IEEE 802.11 and ADSL when exposed to different load conditions; and identify the effects of other services such as FTP, Email and HTTP in VoIP and IPTV demands. In our work we use OpNet, a popular network simulator in the academic environment. The simulation results provide important guidelines about the maximum capacity of each technology keeping in mind QoS requirements; on the other hand, they enable identification of the most damaging services for VoIP and IPTV. The second objective is the implementation of a framework that allows monitoring VoIP and IPTV services, analyzing the collected performance measurements, and storing them in a database; all these processes will be performed in real time in order to keep the database up to date. The results available by this framework allow a better network management, the service providers can have current information about their services performance, and consequently it is possible to identify a failure or a future trend

Investigation of reactive TCP and link characteristics estimation for wireless links

Master'sMASTER OF SCIENC

Robust Controller for Delays and Packet Dropout Avoidance in Solar-Power Wireless Network

Solar Wireless Networked Control Systems (SWNCS) are a style of distributed control systems where sensors, actuators, and controllers are interconnected via a wireless communication network. This system setup has the benefit of low cost, flexibility, low weight, no wiring and simplicity of system diagnoses and maintenance. However, it also unavoidably calls some wireless network time delays and packet dropout into the design procedure. Solar lighting system offers a clean environment, therefore able to continue for a long period. SWNCS also offers multi Service infrastructure solution for both developed and undeveloped countries. The system provides wireless controller lighting, wireless communications network (WI-FI/WIMAX), CCTV surveillance, and wireless sensor for weather measurement which are all powered by solar energy

Video Quality Prediction for Video over Wireless Access Networks (UMTS and WLAN)

Transmission of video content over wireless access networks (in particular, Wireless Local Area Networks (WLAN) and Third Generation Universal Mobile Telecommunication System (3G UMTS)) is growing exponentially and gaining popularity, and is predicted to expose new revenue streams for mobile network operators. However, the success of these video applications over wireless access networks very much depend on meeting the user’s Quality of Service (QoS) requirements. Thus, it is highly desirable to be able to predict and, if appropriate, to control video quality to meet user’s QoS requirements. Video quality is affected by distortions caused by the encoder and the wireless access network. The impact of these distortions is content dependent, but this feature has not been widely used in existing video quality prediction models. The main aim of the project is the development of novel and efficient models for video quality prediction in a non-intrusive way for low bitrate and resolution videos and to demonstrate their application in QoS-driven adaptation schemes for mobile video streaming applications. This led to five main contributions of the thesis as follows:(1) A thorough understanding of the relationships between video quality, wireless access network (UMTS and WLAN) parameters (e.g. packet/block loss, mean burst length and link bandwidth), encoder parameters (e.g. sender bitrate, frame rate) and content type is provided. An understanding of the relationships and interactions between them and their impact on video quality is important as it provides a basis for the development of non-intrusive video quality prediction models.(2) A new content classification method was proposed based on statistical tools as content type was found to be the most important parameter. (3) Efficient regression-based and artificial neural network-based learning models were developed for video quality prediction over WLAN and UMTS access networks. The models are light weight (can be implemented in real time monitoring), provide a measure for user perceived quality, without time consuming subjective tests. The models have potential applications in several other areas, including QoS control and optimization in network planning and content provisioning for network/service providers.(4) The applications of the proposed regression-based models were investigated in (i) optimization of content provisioning and network resource utilization and (ii) A new fuzzy sender bitrate adaptation scheme was presented at the sender side over WLAN and UMTS access networks. (5) Finally, Internet-based subjective tests that captured distortions caused by the encoder and the wireless access network for different types of contents were designed. The database of subjective results has been made available to research community as there is a lack of subjective video quality assessment databases.Partially sponsored by EU FP7 ADAMANTIUM Project (EU Contract 214751

IEEE 802.11 wireless LAN traffic analysis: a cross-layer approach

textThe deployment of broadband wireless data networks, e.g., wireless local area networks (WLANs) [29], experienced tremendous growth in the last several years, and this trend is continuously gaining momentum. In fact, WLAN is becoming an indispensable component of the modern telecommunication infrastructure. Despite this optimistic outlook, however, little is known about the impact of the wireless channel on the characteristics of WLAN traffic. This dissertation characterizes the correlation structures of WLAN channel with traffic statistics from a cross-layer point of view, and provides new measurement methodologies and statistical models for WLAN networks. Currently WLAN standards are designed within the paradigm of the layered network architecture. For example, the architecture of IEEE 802.11 vii is almost identical to the Ethernet. However, wireless networks are fundamentally different from their wired peers due to the shift of transmission media from cables to over-the-air radio waves. This transition exposes wireless systems to the influence of radio propagation, and more importantly, to the temporal and spacial fluctuations of the radio channel that can actually be propagated up to upper layers. However, the current WLAN architecture isolates network layers, and largely ignores this impact. Therefore, we believe that a cross-layer based approach is necessary to understand and reflect this underlying impact of the channel to the upper layers of the network, especially in relation to WLAN traffic behavior. Measurement is one of the fundamental tools used to quantify radio propagation. As part of this dissertation, a complete framework for a measurement methodology, including hardware, software, and measurement procedures, is established. Characteristics of the propagation channel are estimated from measurement data, and the channel knowledge is applied to the upper layers for more realistic and accurate modeling. In WLAN environments, knowledge of the traffic characteristics is essential for proper network provisioning, and for improving the performance of the IEEE 802.11 standard and network devices, e.g., to design improved MAC schemes, or to build better buffer scheduling algorithms with channel knowledge, etc. Built upon extensive WLAN traffic traces, this dissertation work presents cross-layer models for WLAN throughput predictions, traffic statistics, and link layer characteristics. viii The main goal of this dissertation work is to experiment with and develop new methods for identifying channel characteristics. Thereby utilizing this knowledge, we show how to predict and improve WLAN performance. Within the framework of the developed cross-layer measurement methodology, we conducted extensive measurements in different physical environments and different settings such as office buildings and stores, and (1) show that the impact of the propagation channel can be quantified by using simple large scale channel metric (throughput over longer period of time), and (2) also present the existence of a Doppler effect within today’s WLAN packet traffic at sub-second time scales. We also show the real-world WLAN usage pattern from our measurement results. From this data, we conclude that the key issues to study WLAN networks include accurate site-specific propagation channel modeling and real-time autonomous traffic control.Electrical and Computer Engineerin