Modeling and Performance Analysis of Peer-to-Peer Live Streaming Systems

In recent years, Internet has witnessed a rapid growth in P2P (peer-to-peer) applications, especially, in the live streaming domain. There have been several deployments of largescale industrial level P2P live video systems, e.g., CoolStream, PPLive, Sopcast. Several contemporary measurement studies have verified that thousands of users can simultaneously participate in these systems. Almost all live P2P video systems offer multiple channels (e.g., PPLive can host over 100 channels). It is expected that in near future, live streaming systems with hundreds of user-generated channels will likely have thousands of live channels in total. With such a large number of streaming channels and huge number of participants, there are still some challenging issues needed to be addressed for an efficient P2P live streaming system. This PhD thesis is organized around three such problems related to the P2P live streaming systems. In the first research problem, our focus is on the Dedicated Channels used by a Small numbered Viewers (can be termed as DCSV channels for short) in a multi-channel live streaming system. Usually, these are user generated channels and they suffer adversely from poor channel performance, mainly, due to having a small number of participants. As a result, when a viewer of such a channel explicitly requests for a block of streaming content (commonly referred as a chunk), the probability that the chunk will be available among the existing viewers is less than it would be if the number of viewers was higher in that channel (e.g., viewers in a popular channel). We have proposed HnH (short for Hand-in-Hand), a novel scheme of cross-channel resource sharing, in order to solve the performance problem of DCSV channels due to their small number of viewers. We next develop a discrete-time stochastic model in order to analyze its efficiency. In the second research problem, we focus on the Free riders who only want to download and watch the streaming content from their neighboring peers but are unwilling to upload any content to their neighbors. The presence of free riders impose obstacle to the stability of any live streaming system because of consuming bandwidth from the system without significant contribution. We have investigated the performance of a Live streaming system with and without the presence of a free riders. First, we develop a discrete-time stochastic model and then compare the probability of continuous playback without any free rider and with certain amount of free riders. Next, we introduce a simple incentive mechanism and modify our stochastic model in order to accommodate the incentive mechanism. Then we compare the result of probability of continuous playback with and without having an incentive mechanism. Our work shows that presence of an incentive mechanism improves the overall system performance. In the third research problem, we focus on less motivated peers who are not interested to upload streaming contents to their neighbors if those contents are not from the channels they are watching. The context of this work is related to our first research problem where we have proposed the HnH scheme and for simplicity have considered that all the peers from all participating DCSV channels are motivated to cooperate. However, in practice, some of them may behave selfish and become less motivated to help peers from other channels. In this work, we investigate the performance of a HnH scheme based Live streaming system with and without the presence of less motivated peers. First, we develop a discrete-time stochastic model and then compare the probability of continuous playback without any selfish peer and with certain amount of selfish peers. Next, we introduce a simple incentive mechanism and modify our stochastic model accordingly. Finally, we compare the result of probability of continuous playback with and without incentive mechanism. Our work shows that presence of an incentive mechanism improves the over all system performance due to the fact that less motivated peers are motivated to cooperate more by the improved performance

Peer-to-peer television for the IP multimedia subsystem

Peer-to-peer (P2P) video streaming has generated a significant amount of interest in both the research community and the industry, which find it a cost-effective solution to the user scalability problem. However, despite the success of Internet-based applications, the adoption has been limited for commercial services, such as Internet Protocol Television (IPTV). With the advent of the next-generation-networks (NGN) based on the IP Multimedia Subsystem (IMS), advocating for an open and inter-operable architecture, P2P emerges as a possible alternative in situations where the traditional mechanisms are not possible or economically feasible. This work proposes a P2P IPTV architecture for an IMS-based NGN, called P2PTV, which allows one or more service providers to use a common P2P infrastructure for streaming the TV channels to their subscribers. Instead of using servers, we rely on the uploading capabilities of the user equipments, like set-top boxes, located at the customers’ premise. We comply with the existing IMS and IPTV standards from the 3rd Generation Partnership Project (3GPP) and the Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN) bodies, where a centralized P2PTV application server (AS) manages the customer access to the service and the peer participation. Because watching TV is a complex and demanding user activity, we face two significant challenges. The first is to accommodate the mandatory IMS signaling, which reserves in the network the necessary QoS resources during every channel change, establishing a multimedia session between communicating peers. The second is represented by the streaming interruptions, or churn, when the uploading peer turns off or changes its current TV channel. To tackle these problems, we propose two enhancements. A fast signaling method, which uses inactive uploading sessions with reserved but unused QoS, to improve the tuning delay for new channel users. At every moment, the AS uses a feedback based algorithm to compute the number of necessary sessions that accommodates well the demand, while preventing the over-reservation of resources. We approach with special care mobility situations, where a proactive transfer of the multimedia session context using the IEEE 802.21 standard offers the best alternative to current methods. The second enhancement addresses the peer churn during channel changes. With every TV channel divided into a number of streams, we enable peers to download and upload streams different from their current channel, increasing the stability of their participation. Unlike similar work, we benefit from our estimation of the user demand and propose a decentralized method for a balanced assignment of peer bandwidth. We evaluate the performance of the P2PTV through modeling and large-scale computer simulations. A simpler experimental setting, with pure P2P streaming, indicates the improvements over the delay and peer churn. In more complex scenarios, especially with resource-poor peers having a limited upload capacity, we envision P2P as a complementary solution to traditional approaches like IP multicast. Reserving P2P for unpopular TV channels exploits the peer capacity and prevents the necessity of a large number of sparsely used multicast trees. Future work may refine the AS algorithms, address different experimental scenarios, and extend the lessons learned to non-IMS networks. ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------La transmisión de vídeo con tecnologías peer-to-peer (P2P) ha generado un gran interés, tanto en la industria como en la comunidad científica, quienes han encontrado en dicha unión la solución para afrontar los problemas de escalabilidad de la transmisión de vídeo, reduciendo al mismo tiempo sus costes. A pesar del éxito de estos mecanismos en Internet, la transmisión de vídeo mediante técnicas P2P no se ha utilizado en servicios comerciales como puede ser el de televisión por IP (IPTV). Con la aparición de propuestas de redes de próxima generación basadas en el IP Multimedia Subsystem (IMS), que permite una arquitectura abierta e interoperable, los mecanismos basados en P2P emergen como posibles alternativas en situaciones donde los mecanismos tradicionales de transmisión de vídeo no se pueden desplegar o no son económicamente viables. Esta tesis propone una arquitectura de servicio de televisión peer-to-peer para una red de siguiente generación basada en IMS, que abreviaremos como P2PTV, que permite a uno o más proveedores de servicio utilizar una infraestructura P2P común para la transmisión de canales de TV a sus suscriptores. En vez de utilizar varios servidores, proponemos utilizar la capacidad de envío de los equipos de usuario, como los set-top boxes, localizados en el lado del cliente. En esta tesis extendemos los trabajos de estandarización sobre IMS IPTV de los organismos 3rd Generation Partnership Project (3GPP) y del Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN), donde un servidor de aplicación (AS) central de P2PTV administra el acceso de los clientes al servicio y permite compartir los recursos de los equipos. Debido a que el acceso a los canales de TV por parte de los usuarios es una actividad compleja, nos enfrentamos a dos retos importantes. El primero es administrar la señalización de IMS, con la cual se reservan los recursos de QoS necesarios durante cada cambio de canal, estableciendo una sesión multimedia entre los diferentes elementos de la comunicación. El segundo está representado por las interrupciones de la reproducción de video, causado por los equipos que sirven dicho vídeo cuando estos se desconectan del sistema o cuando cambian de canal. Para afrontar estos retos, proponemos dos mejoras al sistema. La primera mejora introduce el método de señalización rápida, en la cual se utilizan sesiones multimedia inactivas pero con recursos reservados para acelerar las conexiones entre usuarios. En cada momento, el AS utiliza la información extraída del algoritmo propuesto, que calcula el número de sesiones necesarias para administrar la demanda de conexiones, pero sin realizar una sobre-estimación, manteniendo bajo el uso de los recursos. Hemos abordado con especial cuidado la movilidad de los usuarios, donde se ha propuesto una transferencia de sesión pro-activa utilizando el estándar IEEE 802.21, el cual brinda una mejor alternativa que los métodos propuestos hasta la fecha. La segunda mejora se enfoca en las desconexiones de usuarios durante cambios de canal. Dividiendo los canales de TV en varios segmentos, permitimos a los equipos descargar o enviar diferentes partes de cualquier canal, aumentando la estabilidad de su participación. A diferencia de otros trabajos, nuestra propuesta se beneficia de la estimación de la demanda futura de los usuarios, proponiendo un método descentralizado para una asignación balanceada del ancho de banda de los equipos. Hemos evaluado el rendimiento del sistema P2PTV a través de modelado y de simulaciones de ordenador en sistemas IPTV de gran escala. Una configuración simple, con envío P2P puro, indica mejoras en el retardo y número de desconexiones de usuarios. En escenarios más complejos, especialmente con equipos con pocos recursos en la subida, sugerimos el uso de P2P como una solución complementaria a las soluciones tradicionales de multicast IP. Reservando el uso de P2P para los canales de TV poco populares, se permite explotar los recursos de los equipos y se previene la necesidad de un alto número de árboles multicast dispersos. Como trabajo futuro, se propone refinar los algoritmos del AS, abordar diferentes escenarios experimentales y también extender las lecciones aprendidas en esta tesis a otros sistemas no basados en IMS

Configuration Management of Distributed Systems over Unreliable and Hostile Networks

Economic incentives of large criminal profits and the threat of legal consequences have pushed criminals to continuously improve their malware, especially command and control channels. This thesis applied concepts from successful malware command and control to explore the survivability and resilience of benign configuration management systems. This work expands on existing stage models of malware life cycle to contribute a new model for identifying malware concepts applicable to benign configuration management. The Hidden Master architecture is a contribution to master-agent network communication. In the Hidden Master architecture, communication between master and agent is asynchronous and can operate trough intermediate nodes. This protects the master secret key, which gives full control of all computers participating in configuration management. Multiple improvements to idempotent configuration were proposed, including the definition of the minimal base resource dependency model, simplified resource revalidation and the use of imperative general purpose language for defining idempotent configuration. Following the constructive research approach, the improvements to configuration management were designed into two prototypes. This allowed validation in laboratory testing, in two case studies and in expert interviews. In laboratory testing, the Hidden Master prototype was more resilient than leading configuration management tools in high load and low memory conditions, and against packet loss and corruption. Only the research prototype was adaptable to a network without stable topology due to the asynchronous nature of the Hidden Master architecture. The main case study used the research prototype in a complex environment to deploy a multi-room, authenticated audiovisual system for a client of an organization deploying the configuration. The case studies indicated that imperative general purpose language can be used for idempotent configuration in real life, for defining new configurations in unexpected situations using the base resources, and abstracting those using standard language features; and that such a system seems easy to learn. Potential business benefits were identified and evaluated using individual semistructured expert interviews. Respondents agreed that the models and the Hidden Master architecture could reduce costs and risks, improve developer productivity and allow faster time-to-market. Protection of master secret keys and the reduced need for incident response were seen as key drivers for improved security. Low-cost geographic scaling and leveraging file serving capabilities of commodity servers were seen to improve scaling and resiliency. Respondents identified jurisdictional legal limitations to encryption and requirements for cloud operator auditing as factors potentially limiting the full use of some concepts

Toward Open and Programmable Wireless Network Edge

Increasingly, the last hop connecting users to their enterprise and home networks is wireless. Wireless is becoming ubiquitous not only in homes and enterprises but in public venues such as coffee shops, hospitals, and airports. However, most of the publicly and privately available wireless networks are proprietary and closed in operation. Also, there is little effort from industries to move forward on a path to greater openness for the requirement of innovation. Therefore, we believe it is the domain of university researchers to enable innovation through openness. In this thesis work, we introduce and defines the importance of open framework in addressing the complexity of the wireless network. The Software Defined Network (SDN) framework has emerged as a popular solution for the data center network. However, the promise of the SDN framework is to make the network open, flexible and programmable. In order to deliver on the promise, SDN must work for all users and across all networks, both wired and wireless. Therefore, we proposed to create new modules and APIs to extend the standard SDN framework all the way to the end-devices (i.e., mobile devices, APs). Thus, we want to provide an extensible and programmable abstraction of the wireless network as part of the current SDN-based solution. In this thesis work, we design and develop a framework, weSDN (wireless extension of SDN), that extends the SDN control capability all the way to the end devices to support client-network interaction capabilities and new services. weSDN enables the control-plane of wireless networks to be extended to mobile devices and allows for top-level decisions to be made from an SDN controller with knowledge of the network as a whole, rather than device centric configurations. In addition, weSDN easily obtains user application information, as well as the ability to monitor and control application flows dynamically. Based on the weSDN framework, we demonstrate new services such as application-aware traffic management, WLAN virtualization, and security management

Application of service composition mechanisms to Future Networks architectures and Smart Grids

Aquesta tesi gira entorn de la hipòtesi de la metodologia i mecanismes de composició de serveis i com es poden aplicar a diferents camps d'aplicació per a orquestrar de manera eficient comunicacions i processos flexibles i sensibles al context. Més concretament, se centra en dos camps d'aplicació: la distribució eficient i sensible al context de contingut multimèdia i els serveis d'una xarxa elèctrica intel·ligent. En aquest últim camp es centra en la gestió de la infraestructura, cap a la definició d'una Software Defined Utility (SDU), que proposa una nova manera de gestionar la Smart Grid amb un enfocament basat en programari, que permeti un funcionament molt més flexible de la infraestructura de xarxa elèctrica. Per tant, revisa el context, els requisits i els reptes, així com els enfocaments de la composició de serveis per a aquests camps. Fa especial èmfasi en la combinació de la composició de serveis amb arquitectures Future Network (FN), presentant una proposta de FN orientada a serveis per crear comunicacions adaptades i sota demanda. També es presenten metodologies i mecanismes de composició de serveis per operar sobre aquesta arquitectura, i posteriorment, es proposa el seu ús (en conjunció o no amb l'arquitectura FN) en els dos camps d'estudi. Finalment, es presenta la investigació i desenvolupament realitzat en l'àmbit de les xarxes intel·ligents, proposant diverses parts de la infraestructura SDU amb exemples d'aplicació de composició de serveis per dissenyar seguretat dinàmica i flexible o l'orquestració i gestió de serveis i recursos dins la infraestructura de l'empresa elèctrica.Esta tesis gira en torno a la hipótesis de la metodología y mecanismos de composición de servicios y cómo se pueden aplicar a diferentes campos de aplicación para orquestar de manera eficiente comunicaciones y procesos flexibles y sensibles al contexto. Más concretamente, se centra en dos campos de aplicación: la distribución eficiente y sensible al contexto de contenido multimedia y los servicios de una red eléctrica inteligente. En este último campo se centra en la gestión de la infraestructura, hacia la definición de una Software Defined Utility (SDU), que propone una nueva forma de gestionar la Smart Grid con un enfoque basado en software, que permita un funcionamiento mucho más flexible de la infraestructura de red eléctrica. Por lo tanto, revisa el contexto, los requisitos y los retos, así como los enfoques de la composición de servicios para estos campos. Hace especial hincapié en la combinación de la composición de servicios con arquitecturas Future Network (FN), presentando una propuesta de FN orientada a servicios para crear comunicaciones adaptadas y bajo demanda. También se presentan metodologías y mecanismos de composición de servicios para operar sobre esta arquitectura, y posteriormente, se propone su uso (en conjunción o no con la arquitectura FN) en los dos campos de estudio. Por último, se presenta la investigación y desarrollo realizado en el ámbito de las redes inteligentes, proponiendo varias partes de la infraestructura SDU con ejemplos de aplicación de composición de servicios para diseñar seguridad dinámica y flexible o la orquestación y gestión de servicios y recursos dentro de la infraestructura de la empresa eléctrica.This thesis revolves around the hypothesis the service composition methodology and mechanisms and how they can be applied to different fields of application in order to efficiently orchestrate flexible and context-aware communications and processes. More concretely, it focuses on two fields of application that are the context-aware media distribution and smart grid services and infrastructure management, towards a definition of a Software-Defined Utility (SDU), which proposes a new way of managing the Smart Grid following a software-based approach that enable a much more flexible operation of the power infrastructure. Hence, it reviews the context, requirements and challenges of these fields, as well as the service composition approaches. It makes special emphasis on the combination of service composition with Future Network (FN) architectures, presenting a service-oriented FN proposal for creating context-aware on-demand communication services. Service composition methodology and mechanisms are also presented in order to operate over this architecture, and afterwards, proposed for their usage (in conjunction or not with the FN architecture) in the deployment of context-aware media distribution and Smart Grids. Finally, the research and development done in the field of Smart Grids is depicted, proposing several parts of the SDU infrastructure, with examples of service composition application for designing dynamic and flexible security for smart metering or the orchestration and management of services and data resources within the utility infrastructure

CTRL SHIFT

CTRL SHIFT makes a case for design under contemporary computation. The abstractions of reading, writing, metaphors, mythology, code, cryptography, interfaces, and other such symbolic languages are leveraged as tools for understanding. Alternative modes of knowledge become access points through which users can subvert the control structures of software. By challenging the singular expertise of programmers, the work presented within advocates for the examination of internalized beliefs, the redistribution of networked power, and the collective sabotage of computational authority

Digital Entrepreneurship

This open access book explores the global challenges and experiences related to digital entrepreneurial activities, using carefully selected examples from leading companies and economies that shape world business today and tomorrow. Digital entrepreneurship and the companies steering it have an enormous global impact; they promise to transform the business world and change the way we communicate with each other. These companies use digitalization and artificial intelligence to enhance the quality of decisions and augment their business and customer operations. This book demonstrates how cloud services are continuing to evolve; how cryptocurrencies are traded in the banking industry; how platforms are created to commercialize business, and how, taken together, these developments provide new opportunities in the digitalized era. Further, it discusses a wide range of digital factors changing the way businesses operate, including artificial intelligence, chatbots, voice search, augmented and virtual reality, as well as cyber threats and data privacy management. “Digitalization mirrors the Industrial Revolution’s impact. This book provides a complement of perspectives on the opportunities emanating from such a deep seated change in our economy. It is a comprehensive collection of thought leadership mapped into a very useful framework. Scholars, digital entrepreneurs and practitioners will benefit from this timely work.” Gina O’Connor, Professor of Innovation Management at Babson College, USA “This book defines and delineates the requirements for companies to enable their businesses to succeed in a post-COVID19 world. This book deftly examines how to accomplish and achieve digital entrepreneurship by leveraging cloud computing, AI, IoT and other critical technologies. This is truly a unique “must-read” book because it goes beyond theory and provides practical examples.” Charlie Isaacs, CTO of Customer Connection at Salesforce.com, USA "This book provides digital entrepreneurs useful guidance identifying, validating and building their venture. The international authors developed new perspectives on digital entrepreneurship that can support to create impact ventures.” Felix Staeritz, CEO FoundersLane, Member of the World Economic Forum Digital Leaders Board and bestselling author of FightBack, German

Digital Entrepreneurship

This open access book explores the global challenges and experiences related to digital entrepreneurial activities, using carefully selected examples from leading companies and economies that shape world business today and tomorrow. Digital entrepreneurship and the companies steering it have an enormous global impact; they promise to transform the business world and change the way we communicate with each other. These companies use digitalization and artificial intelligence to enhance the quality of decisions and augment their business and customer operations. This book demonstrates how cloud services are continuing to evolve; how cryptocurrencies are traded in the banking industry; how platforms are created to commercialize business, and how, taken together, these developments provide new opportunities in the digitalized era. Further, it discusses a wide range of digital factors changing the way businesses operate, including artificial intelligence, chatbots, voice search, augmented and virtual reality, as well as cyber threats and data privacy management. “Digitalization mirrors the Industrial Revolution’s impact. This book provides a complement of perspectives on the opportunities emanating from such a deep seated change in our economy. It is a comprehensive collection of thought leadership mapped into a very useful framework. Scholars, digital entrepreneurs and practitioners will benefit from this timely work.” Gina O’Connor, Professor of Innovation Management at Babson College, USA “This book defines and delineates the requirements for companies to enable their businesses to succeed in a post-COVID19 world. This book deftly examines how to accomplish and achieve digital entrepreneurship by leveraging cloud computing, AI, IoT and other critical technologies. This is truly a unique “must-read” book because it goes beyond theory and provides practical examples.” Charlie Isaacs, CTO of Customer Connection at Salesforce.com, USA "This book provides digital entrepreneurs useful guidance identifying, validating and building their venture. The international authors developed new perspectives on digital entrepreneurship that can support to create impact ventures.” Felix Staeritz, CEO FoundersLane, Member of the World Economic Forum Digital Leaders Board and bestselling author of FightBack, German

ECLAP 2012 Conference on Information Technologies for Performing Arts, Media Access and Entertainment

It has been a long history of Information Technology innovations within the Cultural Heritage areas. The Performing arts has also been enforced with a number of new innovations which unveil a range of synergies and possibilities. Most of the technologies and innovations produced for digital libraries, media entertainment and education can be exploited in the field of performing arts, with adaptation and repurposing. Performing arts offer many interesting challenges and opportunities for research and innovations and exploitation of cutting edge research results from interdisciplinary areas. For these reasons, the ECLAP 2012 can be regarded as a continuation of past conferences such as AXMEDIS and WEDELMUSIC (both pressed by IEEE and FUP). ECLAP is an European Commission project to create a social network and media access service for performing arts institutions in Europe, to create the e-library of performing arts, exploiting innovative solutions coming from the ICT

Radio evolution: conference proceedings

Fundação para a Ciência e a Tecnologia (FCT