An efficient pending interest table control management in named data network

Named Data Networking (NDN) is an emerging Internet architecture that employs a new network communication model based on the identity of Internet content. Its core component, the Pending Interest Table (PIT) serves a significant role of recording Interest packet information which is ready to be sent but in waiting for matching Data packet. In managing PIT, the issue of flow PIT sizing has been very challenging due to massive use of long Interest lifetime particularly when there is no flexible replacement policy, hence affecting PIT performance. The aim of this study is to propose an efficient PIT Control Management (PITCM) approach to be used in handling incoming Interest packets in order to mitigate PIT overflow thus enhancing PIT utilization and performance. PITCM consists of Adaptive Virtual PIT (AVPIT) mechanism, Smart Threshold Interest Lifetime (STIL) mechanism and Highest Lifetime Least Request (HLLR) policy. The AVPIT is responsible for obtaining early PIT overflow prediction and reaction. STIL is meant for adjusting lifetime value for incoming Interest packet while HLLR is utilized for managing PIT entries in efficient manner. A specific research methodology is followed to ensure that the work is rigorous in achieving the aim of the study. The network simulation tool is used to design and evaluate PITCM. The results of study show that PITCM outperforms the performance of standard NDN PIT with 45% higher Interest satisfaction rate, 78% less Interest retransmission rate and 65% less Interest drop rate. In addition, Interest satisfaction delay and PIT length is reduced significantly to 33% and 46%, respectively. The contribution of this study is important for Interest packet management in NDN routing and forwarding systems. The AVPIT and STIL mechanisms as well as the HLLR policy can be used in monitoring, controlling and managing the PIT contents for Internet architecture of the future

Diseño y evaluación de un sistema de distribución de contenido para vídeo adaptativo sobre Android

Durante los últimos años, la tecnología ha dado pasos agigantados en su evolución. La sociedad vive a un ritmo frenético y exige conexiones más veloces y tiempos de espera cada día menores. Debido a esto, se ha aumentado la velocidad y ancho de banda tanto en redes Wi-Fi como en redes de datos, véase las nuevas incorporaciones al mercado de tecnologías punteras como el 4G y la fibra óptica, que ayudan a los usuarios a adquirir una mayor velocidad en sus conexiones a Internet. Vivimos en un mundo sin tiempo y con prisas, y por ello, las tecnologías focalizan sus objetivos en cubrir, principalmente, esta demanda de velocidad. La sociedad hace un gran uso de vídeos y fotos en todo momento, toda red social actualmente ya admite tanto imágenes como vídeos para compartir, por ello en este proyecto nos centramos en la importancia de los vídeos. La existencia de un aumento en el tráfico de streaming en Internet hace que los usuarios requieran mayor velocidad de carga en vídeos. Además, el número de dispositivos desde los cuales podemos reproducir estos contenidos ha incrementado gracias a smartphones, tablets, smart TV’s, etc., de manera que podemos ver desde cualquier lugar nuestros vídeos favoritos a través de conexiones 3G, 4G o incluso Wi-Fi. Sin embargo, no todos los dispositivos pueden reproducir todo lo que desearíamos, debido a la existencia de diferentes protocolos de streaming, diferentes formatos, etc., que hacen que no todos los dispositivos sean compatibles con estas especificaciones. Para resolver estos problemas, hemos utilizado en este proyecto un nuevo estándar que permite reproducir contenido multimedia en streaming adaptado a cualquier dispositivo y red de comunicaciones, conocido como DASH (Dynamic Adaptive Streaming over HTTP). Una vez solucionado el primer problema, se quiso indagar en cómo hacer que estos vídeos streaming tuviesen un menor retardo y tiempo de carga. Basándose en estas necesidades, se ha realizado este Trabajo Fin de Grado, en el que se ha implementado y diseñado un sistema para el análisis y funcionamiento de las redes centradas en el contenido (CCN) en un terminal Android. El sistema consiste en crear una red virtual basada en CCNx que nos permite estudiar mediante el estándar DASH, cómo se comporta un terminal Android en la reproducción de vídeos por streaming en redes Wi-Fi. Gracias a las redes CCN conseguiremos un tiempo de carga menor ya que en estas redes se almacenarán los fragmentos de vídeo que pasen por las mismas y ya no siempre será necesario conectar con el servidor. De esta manera, este proyecto se puede dividir en diferentes etapas. La primera de ellas consiste en, por un lado, la creación de ficheros de metadatos que describen el contenido disponible, entre otras características, (ficheros Media Presentation Description, MPD) para la reproducción de los vídeos. Por otro lado, la búsqueda de herramientas que manejen estos ficheros. Para ello se pensó en el reproductor VLC, pero finalmente se decantó por el reproductor multimedia para Android, Osmo4, debido a que es de código abierto y permite una mayor facilidad en su configuración. La segunda parte, es la configuración de la red CCNx que nos permitirá almacenar las trazas del vídeo en una caché para que el cliente adquiera el vídeo en menor tiempo sin tener que pasar por el servidor. Por último, se realizó una batería de pruebas mediante un emulador y un terminal Android (HTC Legend) para finalizar con el estudio. Gracias a estas pruebas podemos demostrar que este tipo de redes centradas en la información, junto con DASH, nos ayudan a recortar tiempos de carga del vídeo, lo que mejora la experiencia final de los usuarios.During years, technology has grown rapidly. Society lives with no time for anything and they demand faster connections and lower waiting times. As a result, as far as bandwidth and Wi-Fi networks is concerned, speed has increased. For example, the new additions of 4G and fiber optics technologies. These technologies help users to have better internet connections. Technologies are constantly improving to solve these problems. Society makes massive use of videos and photos at any time, even in the social networks that currently support images and videos to share. Therefore, we stress the importance of the videos today. The existence of an increasing traffic of streaming on the Internet makes users to require fastest access in the videos. In addition, the number of devices that we can reproduce has increased thanks to smartphones, tablets, smart TVs, etc. We can see anywhere our favorite videos with 3G, 4G connections or even Wi-Fi. However, not all devices can reproduce everything because there are different protocols of different formats, streaming, etc. To resolve these problems, a possible solution might be to create a new standard allowing users to play multimedia content streaming from any device. For this reason the standard called DASH (Dynamic Adaptive Streaming over HTTP) was created standard. Once the first problem is solved, we are looking for making these streaming videos to have faster loading time. For this reason, we use CCNx networks that allow us a lower playback time, because of its capability to cache video frames at the own routers. Based on these needs has been carried out this thesis, in which we have designed a system for analysis and operation of networks CCN on an Android device. The system consists of a virtual network based on CCNx that allows us to study how it plays an Android device videos streaming according to the DASH standard. With CCNx networks we will get less load time, because the video frames that pass through it will be stored there, reducing the number of hops to retrieve the content. This thesis is divided into different parts. The first part consists of the creation of files for metadata that describes the content available, among other characteristics, (Media Presentation Description, MPD files) for the playback of videos. On the other hand, the search for tools that handle these files. We started using VLC Player, but finally we have used the Media Player for Android, Osmo4, since it is open source too and it includes extra functionalities. The second part is the network configuration CCNx allowing us to store traces of the video in a buffer so that the client has the video in less time. Finally, a battery of tests using a simulator of Android and HTC Legend terminal was to end with the study. These tests can show if such networks help us to have less load times or, however, its improvements are not good.Ingeniería Telemátic

Applications of Game Theory to Multi-Agent Coordination Problems in Communication Networks

Recent years there has been a growing interest in the study of distributed control mechanisms for use in communication networks. A fundamental assumption in these models is that the participants in the network are willing to cooperate with the system. However, there are many instances where the incentives to cooperate is missing. Then, the agents may seek to achieve their own private interests by behaving strategically. Often, such selfish choices lead to inefficient equilibrium state of the system, commonly known as the tragedy of commons in Economics terminology. Now, one may ask the following question: how can the system be led to the socially optimal state in spite of selfish behaviors of its participants? The traditional control design framework fails to provide an answer as it does not take into account of selfish and strategic behavior of the agents. The use of game theoretical methods to achieve coordination in such network systems is appealing, as it naturally captures the idea of rational agents taking locally optimal decisions. In this thesis, we explore several instances of coordination problems in communication networks that can be analyzed using game theoretical methods. We study one coordination problem each, from each layer of TCP/IP reference model - the network model used in the current Internet architecture. First, we consider societal agents taking decisions on whether to obtain content legally or illegally, and tie their behavior to questions of performance of content distribution networks. We show that revenue sharing with peers promote performance and revenue extraction from content distribution networks. Next, we consider a transport layer problem where applications compete against each other to meet their performance objectives by selfishly picking congestion controllers. We establish that tolling schemes that incentivize applications to choose one of several different virtual networks catering to particular needs yields higher system value. Hence, we propose the adoption of such virtual networks. We address a network layer question in third problem. How do the sources in a wireless network split their traffic over the available set of paths to attain the lowest possible number of transmissions per unit time? We develop a two level distributed controller that attains the optimal traffic split. Finally, we study mobile applications competing for channel access in a cellular network. We show that the mechanism where base station conducting sequence of second price auctions and providing channel access to the winner achieves the benefits of the state of art solution, Largest Queue First policy

Objective predictors of subjective aesthetic ratings of web pages

This research is concerned with the effect of visual stimulus on decision-­‐making and opinions, what visual aspects of a page affect very early impressions of web sites, and how this relates to computational methods of prediction and evaluation of web pages. The aim of this study was to discover whether there are identifiable visual attributes of web pages that can be used to predict subjective opinions. This was explored through three separate studies. These consisted of two correlational studies and a categorisation task. Participants were gained through convenience and snowball sampling, and the materials reviewed were two distinct sets of web pages. Cards sorts, laddering and an online data collection tool were used to gather the information. Both qualitative and quantitative analysis was used to explore the information. The visual attributes found to correlate with subjective opinions were inconsistent across the two correlational studies. Study One had a number of limitations that may have contributed to this inconsistency. Concrete findings were that levels of encouragement and discouragement influenced by web pages are on two distinct scales, as, although there is a negative correlation between them, a large number of pages were rated poorly on both scales. The similarity between the card sort and questionnaire results had consistent findings for predictors of low-­‐rated web pages. The findings from the cards sorts also show that users are able to make preference judgements of web pages without being able to understand the content. An application of the findings regarding prediction of low-­‐rated pages would be to create web design optimisation system, enabling web pages to be reviewed computationally. Although this should never replace user testing, it may provide an economical alternative during the early stages of design