Part 1: acceptance test and administration of a farm of servers. Part 2: improving TCP performance in underwater wireless sensor networks

Dissertação de mestrado, Engenharia Informática, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2017Abstract 1 During the last decades, companies and organizations have focused on how to provide to the end-users or clients with web services or applications to make them more closer and involved to the activity. Therefore, many enterprises through their direction of the IT service, propose varieties of applications that allow to the stakeholders to perform what they need. The aim of this report is to present what the application integration job is and to report the missions that I have been able to carry out such as application integration, application qualification, and acceptance tests. This represents in total: - 19 qualified applications, - 33 administrated serversResumo 1 Ao longo das últimas décadas, as empresas e as organizações concentraram-se na forma de fornecer aos usuários finais ou clientes, serviços Web ou aplicativos para torná-los mais próximos e envolvidos na actividade. Portanto, muitas empresas através da sua direcção do serviço de Tecnólogia da Informação TI, propõem variedades de aplicativos que permitem às partes interessadas realizar o que necessitam. O objectivo deste relatório é apresentar o que é o trabalho de integração de aplicativos e as missões que fui capaz de executar, como a integração de aplicativos, a qualificação de aplicativos e testes de aceitação. Isto representa no total: - 19 aplicações qualificadas, - 33 servidores administradosAbstract 2 Underwater wireless sensor networks (UWSNs) are becoming popular due to their important role in different applications, such as offshore search and underwater monitoring. However, the data transmission in this underwater environment is impacted by various aspects such as bandwidth usage limitation, surrounding noise and large acoustic propagation delays. Therefore, communication itself is an outstanding challenge. The well-known traditional transmission control protocol (TCP), one of the most used transport protocol on the internet, is not suitable to enable this technology. Even though TCP variants for the wireless network are not foolproof in an underwater environment, their use could probably be more difficult in such a multi-hop communication system. We have chosen Newreno for our study. This variant is a modern implementation that includes the four congestion control algorithms. These algorithms have proved to be effective when it comes to terrestrial networks which could be a basis for our study. In addition, Newreno is known for its algorithm of recovery of several segments lost within the same sending window. In this dissertation, we have conducted a general study of UWSN technology and examined methods to improve TCP performance in a multi-hop UWSN. And then, we propose Underwater-Newreno (U-Newreno) our enhanced version of Newreno to improve TCP performance in UWSN. U-Newreno consists of two major modifications: controlling the maximum size of the congestion window and the adaptation of the round trip time (RTT) timeout. The results of simulations carried out with the Aquasim simulator show improvements of performances in terms of gain of: packets delivery Retransmission ratio of packets delivery.Resumo 2 As redes de sensores sem fio subaquáticos (Underwater Wireless Sensor Networks- UWSN) estão-se a tornar cada vez mais populares devido à sua importância em diferentes aplicações, como a pesquisa offshore e monitoramento subaquático. No entanto, a transmissão de dados neste ambiente subaquático sofre devido a vários factores, como a limitação do uso da largura de banda, o ruído envolvente e grandes atrasos de propagação acústica. Portanto, a comunicação é um desafio problemático. O familiar transmission control protocol (TCP) tradicional, um dos protocolos de transporte mais utilizados na internet, não é adequado para habilitar esta tecnologia. Mesmo que as variantes TCP para a rede sem fio não sejam infalíveis num ambiente subaquático, o seu uso provavelmente pode ser mais difícil num sistema de comunicação de múltiplos saltos. Nós escolhemos o Newreno para o nosso estudo. Esta variante é uma implementação moderna que inclui os quatro algoritmos de controle de congestionamento. Estes algoritmos demonstraram a sua eficácia em redes terrestres que poderiam ser uma base para o nosso estudo. Além disso, Newreno é conhecido pelo seu algoritmo de recuperação de vários segmentos perdidos dentro da mesma janela de envio. Nesta dissertação, realizamos um estudo geral da tecnologia UWSN e examinamos métodos para melhorar o desempenho do TCP num UWSN de vários saltos. E então, propomos a U-Newreno (Underwater-Newreno), a nossa versão melhorada do Newreno para melhorar o desempenho do TCP no UWSN. O U-Newreno consiste em duas modificações principais: controlar o tamanho máximo da janela de congestionamento e a adaptação do tempo limite “Round Trip Time”(RTT). Os resultados das simulações realizadas com o simulador Aquasim mostram melhorias nos desempenhos em termos de ganho de: • entrega de pacotes • Taxa de retransmissão da entrega de pacotes

A cross-layer quality-oriented energy-efficient scheme for multimedia delivery in wireless local area networks

Wireless communication technologies, although emerged only a few decades ago, have grown fast in both popularity and technical maturity. As a result, mobile devices such as Personal Digital Assistants (PDA) or smart phones equipped with embedded wireless cards have seen remarkable growth in popularity and are quickly becoming one of the most widely used communication tools. This is mainly determined by the flexibility, convenience and relatively low costs associated with these devices and wireless communications. Multimedia applications have become by far one of the most popular applications among mobile users. However this type of application has very high bandwidth requirements, seriously restricting the usage of portable devices. Moreover, the wireless technology involves increased energy consumption and consequently puts huge pressure on the limited battery capacity which presents many design challenges in the context of battery powered devices. As a consequence, power management has raised awareness in both research and industrial communities and huge efforts have been invested into energy conservation techniques and strategies deployed within different components of the mobile devices. Our research presented in this thesis focuses on energy efficient data transmission in wireless local networks, and mainly contributes in the following aspects: 1. Static STELA, which is a Medium Access Control (MAC) layer solution that adapts the sleep/wakeup state schedule of the radio transceiver according to the bursty nature of data traffic and real time observation of data packets in terms of arrival time. The algorithm involves three phases– slow start phase, exponential increase phase, and linear increase phase. The initiation and termination of each phase is self-adapted to real time traffic and user configuration. It is designed to provide either maximum energy efficiency or best Quality of Service (QoS) according to user preference. 2. Dynamic STELA, which is a MAC layer solution deployed on the mobile devices and provides balanced performance between energy efficiency and QoS. Dynamic STELA consists of the three phase algorithm used in static STELA, and additionally employs a traffic modeling algorithm to analyze historical traffic data and estimate the arrival time of the next burst. Dynamic STELA achieves energy saving through intelligent and adaptive increase of Wireless Network Interface Card (WNIC) sleeping interval in the second and the third phase and at the same time guarantees delivery performance through optimal WNIC waking timing before the estimated arrival of new data burst. 3. Q-PASTE, which is a quality-oriented cross-layer solution with two components employed at different network layers, designed for multimedia content delivery. First component, the Packet/ApplicaTion manager (PAT) is deployed at the application layer of both service gateway and client host. The gateway level PAT utilizes fast start, as a widely supported technique for multimedia content delivery, to achieve high QoS and shapes traffic into bursts to reduce the wireless transceiver’s duty cycle. Additionally, gateway-side PAT informs client host the starting and ending time of fast start to assist parameter tuning. The client-side PAT monitors each active session and informs the MAC layer about their traffic-related behavior. The second component, dynamic STELA, deployed at MAC layer, adaptively adjusts the sleep/wake-up behavior of mobile device wireless interfaces in order to reduce energy consumption while also maintaining high Quality of Service (QoS) levels. 4. A comprehensive survey on energy efficient standards and some of the most important state-of-the-art energy saving technologies is also provided as part of the work