On the Applicability of Resources Optimization Model for Mitigating Free Riding in P2P System

The survival of peer-to-peer systems depends on the contribution of resources by all the participating peers. Selfish behavior of some peers that do not contribute resources inhibits the expected level of service delivery. Free riding has been found to seriously affect the performance and negates the sharing principle of peer-to-peer networks. In this paper, first, we investigate through simulations the effectiveness of a proposed linear model for mitigating free riding in a P2P system. Second, we extended the initial linear model by incorporating additional constraints on download and upload of each peer. This helps in reducing the effects of free riding behavior on the system. Lastly, we evaluate the impacts of some parameters on the models.Keywords: Peer-to-Peer, Resources, Free rider, Optimization, Constraints, Algorith

A mathematical framework for analyzing incentives in peer-to-peer networks

The existence and performance of peer-to-peer systems depend on thecontribution of resources from interacting peers. One of the challenges ofresource sharing in peer-to-peer systems is free riding. A situation usersattempt to exploit the system by utilizing the resources of others withoutcontributing. We view this from rationality perspective that every peer inthe network will attempt to maximize their utility of the system. In thispaper, we approach the problem of free riders mitigation from utilityoptimization point of view, by modeling each peer's interest as UtilityMaximization Problem (UTP). We propose analytical model for the wholenetwork as a mixed integer linear programming model. The super peers inthe network are given the responsibility of maximizing the utility of all peers connected to them. This is to ensure fairness among the interacting peers and the stability of the entire system. This technique allows peers to either upload or download resources based on their best strategy and interest.Keywords: Free rider, Utility, Peer-to-Peer, Incentives, Maximization,Resource

The state of peer-to-peer network simulators

Networking research often relies on simulation in order to test and evaluate new ideas. An important requirement of this process is that results must be reproducible so that other researchers can replicate, validate and extend existing work. We look at the landscape of simulators for research in peer-to-peer (P2P) networks by conducting a survey of a combined total of over 280 papers from before and after 2007 (the year of the last survey in this area), and comment on the large quantity of research using bespoke, closed-source simulators. We propose a set of criteria that P2P simulators should meet, and poll the P2P research community for their agreement. We aim to drive the community towards performing their experiments on simulators that allow for others to validate their results

An Incentives Model Based on Reputation for P2P Systems, Journal of Telecommunications and Information Technology, 2013, nr 4

In this paper an incentive model to improve the collaboration in peer-to-peer networks is introduced. The proposed solution uses an incentives model associated with reputation issues as a way to improve the performance of a P2P system. The reputation of the all peers in the system is based on their donated resources and on their behavior. Supplying peers use these rules as a way to assign its outgoing bandwidth to the requesting peers during a content distribution. Each peer can build its best paths by using a best-neighbor policy within its neighborhood. A peer can use its best paths to obtain best services related to content search or download. The obtained results show that proposed scheme insulates the misbehaving peers and reduces the free-riding so that the systems performance is maximized

Towards an incentive mechanism for peer-to-peer multimedia live streaming systems

Incentive mechanisms are essential components of peer-topeer systems for file sharing such as BitTorrent, since they enforce peers to share their resources and to participate. Recent P2P systems that distribute live multimedia streams take their inspiration from BitTorrent, but have not defined incentive mechanisms appropriate to the nature of continuous media. In this article, we uncover the way that the incentive mechanisms in BitTorrent are not well suited to streaming live multimedia, and based on P2P systems that we have measured, we propose a new incentive mechanism designed for distribution of live multimedia streaming over a P2P network.

Serviços OTT TV: aspectos técnico-económicos

Mestrado em Engenharia Eletrónica e TelecomunicaçõesThe breadth of availability and variety of online video contents has helped to encourage a far more mobile experience, which has proved particularly popular among younger generations. Over The Top (OTT) services, particularly those on-demand video platforms, became more and more attractive to consumers when compared with the current main TV packages. This document describes how the video OTT Ecosystem works from a technical side. The description presented reaches both ends of the distribution chain: from how the video signals are acquired and processed, thru all the way to how they are delivered to the client, passing by the challenges and consequences that such services have on the network. The main objective of this dissertation is to understand the possibility to create in Portugal a new operator where the core business is video delivery using only OTT services.A amplitude e variedade de conteúdos disponíveis online têm ajudado a promover uma experiência cada ver mais móvel da televisão, serviço que se tem revelado particularmente popular entre os mais jovens. Serviços Over The Top (OTT), sobretudo aqueles disponíveis através de plataformas de video on-demand, têm-se tornado cada vez mais atraentes para os consumidores, em comparação com os atuais pacotes de televisão. Este documento descreve como funciona, do ponto de vista técnico, o ecossistema do vídeo sobre OTT. A descrição apresentada abrange ambas as extremidades da cadeia de distribuição: desde a forma como os sinais de vídeo são adquiridos e processados até ao modo como eles são entregues ao cliente, passando pelos problemas e consequências que tais serviços podem ter na rede. O principal objectivo deste trabalho é contribuir para compreender se é possível criar em Portugal um novo operador onde o core business seja a distribuição de vídeo utilizando apenas serviços OTT

On the Stability of Distribution Topologies in Peer-to-Peer Live Streaming Systems

Peer-to-Peer Live-Streaming-Systeme sind ständigen Störungen ausgesetzt.Insbesondere ermöglichen unzuverlässige Teilnehmer Ausfälle und Angriffe, welche überraschend Peers aus dem System entfernen. Die Folgen solcher Vorfälle werden großteils von der Verteilungstopologie bestimmt, d.h. der Kommunikationsstruktur zwischen den Peers.In dieser Arbeit analysieren wir Optimierungsprobleme welche bei der Betrachtung von Stabilitätsbegriffen für solche Verteilungstopologien auftreten. Dabei werden sowohl Angriffe als auch unkoordinierte Ausfälle berücksichtigt.Zunächst untersuchen wir die Berechnungskomplexität und Approximierbarkeit des Problems resourcen-effiziente Angriffe zu bestimmen. Dies demonstriert Beschränkungen in den Planungsmöglichkeiten von Angreifern und zeigt inwieweit die Topologieparameter die Schwierigkeit solcher Angriffsrobleme beeinflussen. Anschließend studieren wir Topologieformationsprobleme. Dabei sind Topologieparameter vorgegeben und es muss eine passende Verteilungstopologie gefunden werden. Ziel ist es Topologien zu erzeugen, welche den durch Angriffe mit beliebigen Parametern erzeugbaren maximalen Schaden minimieren.Wir identifizieren notwendige und hinreichende Eigenschaften solcher Verteilungstopologien. Dies führt zu mathematisch fundierten Zielstellungen für das Topologie-Management von Peer-to-Peer Live-Streaming-Systemen.Wir zeigen zwei große Klassen effizient konstruierbarer Verteilungstopologien, welche den maximal möglichen, durch Angriffe verursachten Paketverlust minimieren. Zusätzlich beweisen wir, dass die Bestimmung dieser Eigenschaft für beliebige Topologien coNP-vollständig ist.Soll die maximale Anzahl von Peers minimiert werden, bei denen ein Angriff zu ungenügender Stream-Qualität führt, ändern sich die Anforderungen an Verteilungstopologien. Wir zeigen, dass dieses Topologieformationsproblem eng mit offenen Problemen aus Design- und Kodierungstheorie verwandt ist.Schließlich analysieren wir Verteilungstopologien die den durch unkoordinierte Ausfälle zu erwartetenden Paketverlust minimieren. Wir zeigen Eigenschaften und Existenzbedingungen. Außerdem bestimmen wir die Berechnungskomplexität des Auffindens solcher Topologien. Unsere Ergebnisse liefern Richtlinien für das Topologie-Management von Peer-to-Peer Live-Streaming-Systemen und zeigen auf, welche Stabilitätsziele effizient erreicht werden können.The stability of peer-to-peer live streaming systems is constantly challenged. Especially, the unreliability and vulnerability of their participants allows for failures and attacks suddenly disabling certain sets of peers. The consequences of such events are largely determined by the distribution topology, i.e., the pattern of communication between the peers.In this thesis, we analyze a broad range of optimization problems concerning the stability of distribution topologies. For this, we discuss notions of stability against both attacks and failures.At first, we investigate the computational complexity and approximability of finding resource-efficient attacks. This allows to point out limitations of an attacker's planning capabilities and demonstrates the influence of the chosen system parameters on the hardness of such attack problems.Then, we turn to study topology formation problems. Here, a set of topology parameters is given and the task consists in finding an eligible distribution topology. In particular, it has to minimize the maximum damage achievable by attacks with arbitrary attack parameters.We identify necessary and sufficient conditions on attack-stable distribution topologies. Thereby, we give mathematically sound guidelines for the topology management of peer-to-peer live streaming systems.We find large classes of efficiently-constructable topologies minimizing the system-wide packet loss under attacks. Additionally, we show that determining this feature for arbitrary topologies is coNP-complete.Considering topologies minimizing the maximum number of peers for which an attack leads to a heavy decrease in perceived streaming quality, the requirements change. Here, we show that the corresponding topology formation problem is closely related to long-standing open problems of Design and Coding Theory.Finally, we study topologies minimizing the expected packet loss due to uncoordinated peer failures. We investigate properties and existence conditions of such topologies. Furthermore, we determine the computational complexity of constructing them.Our results provide guidelines for the topology management of peer-to-peer live streaming systems and mathematically determine which goals can be achieved efficiently

Digital piracy

Die vorliegende Arbeit behandelt das Thema Digitale Piraterie von Musik und Filmen im Internet aus einer gesamtheitlichen Sicht. Dies umfasst die soziale, technische, rechtliche als auch ökonomische Perspektive, wobei der Fokus auf letztere liegt. Die Gründe für das unrechtmäßige Herunterladen von urheberrechtlich geschützten Inhalten und die Etablierung dieses Verhaltens als ein weltweit verbreitetes Massenphänomen bildet den Schwerpunkt des Kapitels, das die soziale Perspektive dieser Thematik behandelt. Die technische Perspektive liefert nicht nur einen Einblick in DRM Systemen (Systeme zur digitalen Rechteverwaltung) sondern erörtert zudem Systeme, mit deren Hilfe Piraterie überhaupt betrieben wird. Jede Auseinandersetzung mit einer Thematik die über Recht und Unrecht Aussagen trifft benötigt als Rahmen eine Erörterung der hierfür zugrundeliegenden Gesetze. Diese wird im Kapitel "Rechtliche Perspektive" abgehandelt. Im Hauptteil der Arbeit wird zunächst die gegenwärtige Struktur und Vorgehensweise der Musik und Filmindustrie erörtert. Danach wird ein Rahmenkonzept für zukünftige, an die technologischen Fortschritte und Wünsche der modernen Kunden angepasste Geschäftsmodelle geschaffen. Aus diesem Konzept heraus werden insgesamt sieben Geschäftsmodelle präsentiert. Auf die ersten drei Modelle wird hierbei der nähere Fokus gelegt, da sie den gesamten Markt betreffen. Die restlichen vier Modelle sind als Nischenprodukte angedacht, die für einen bestimmten Teil des Marktes interessant sein werden. Abschließend folgen ein Fazit und eine allgemeine Empfehlung an die Musik und Filmindustrie.This master thesis deals with the issue of digital piracy of music and film in the internet from a broad perspective. This includes the social, technical, legal and economic perspective with a focus on the latter. The emphasis of the chapter dealing with social issue lies on the reasons for illegitimate download of copyrighted material and the establishment of this behaviour as a worldwide phenomenon. The technical perspective not only delivers an insight into DRM (digital rights management) systems, but also looks into systems which are used to pirate in the first place. When dealing with a topic about rightful and unlawful behaviour then it is inevitable to look into laws and policies regulating these issues. This will be done in the chapter dealing with the legal perspective. The main focus of this work lies with the economic perspective. This chapter will begin with an analysis of the current structure and practise of the music and the film industry. Later on a framework will be created to derive innovative business models more fitting to the technological developments of recent times and the requirements of modern customers. Out of seven business models presented, the first three will be looked up in detail since they are meant to be adapted to the whole market, whereas the other four models suit only certain segments of the market. Finally the thesis finishes with a conclusion and a general recommendation for the music and film industry

Journal of Telecommunications and Information Technology, nr 4

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