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I-Share is a research project that is part of the larger Freeband Communcation program. See also the official Freeband I-Share site.

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Papers

Toward 3D-IPTV: Design and Implementation of a Stereoscopic and Multiple-Perspective Video Streaming System

Authors: G. Petrovic, D. Farin, P. de With

Abstract: 3D-Video systems allow a user to perceive depth in the viewed scene and to display the scene from arbitrary view- points interactively and on-demand. This paper presents a prototype implementation of a 3D-video streaming system using an IP network. The architecture of our streaming system is layered, where each information layer conveys a single coded video signal or coded scene-description data. We demonstrate the bene¯ts of a layered architecture with two examples: (a) stereoscopic video streaming, (b) monoscopic video streaming with remote multiple-perspective rendering. Our implementation experiments con¯rm that prototyping 3D-video streaming systems is possible with today's software and hardware. Furthermore, our current operational prototype demon- strates that highly heterogeneous clients can coexist in the system, ranging from auto-stereoscopic 3D displays to resource-constrained mobile devices.

Fbref: Freeband/I-Share/P108v1.0

Where: SPIE Stereoscopic Displays and Applications (SDA 2008), vol. 6803 pp. 505-512, January 2008, San Jose, USA.

Keywords: 3D-TV, IPTV, stereoscopic video, view interpolation, depth image, multimedia streaming

Personalized Random Walks for Social Content Retrieval

Authors: Maarten Clements, Arjen P. de Vries, Marcel J.T. Reinders

Abstract: Social content systems contain enormous collections of unstructured user-generated content, annotated by the collaborative effort of regular Internet users. Tag-clouds have become popular interfaces that allow users to query the database by clicking relevant terms. However, these single click queries are often not expressive enough to effectively retrieve the desired content. Using both rating and tagging information, we have created a personalized retrieval model that effectively integrates the personal user preference in the content ranking. We use a random walk model which exploits latent relations in the content ranking. With collaborative annotations from a popular online book catalog, we show that our model outperforms standard tag-based retrieval. Also, our results indicate that individually created annotations are not semantically expressive enough to enable effective retrieval. Finally, we discuss the robustness of our model to well known linguistic problems like synonyms and homographs.

Fbref: Freeband/I-Share/P107v1.0

Where: Proceedings of the Fourteenth Annual Conference of the Advanced School for Computing and Imaging, Heijen, The Netherlands, June 2008

Keywords: Social Networks, Multimedia Retrieval, Collaborative Tagging, Ratings, Personalization

Detecting synonyms in social tagging systems to improve content retrieval

Authors: Maarten Clements, Arjen P. de Vries, Marcel J.T. Reinders

Abstract: Collaborative tagging used in online social content systems contains many synonyms which results in low precision retrieval. We propose a mechanism to identify synonyms that can be used to retrieve more relevant documents by expanding the user's query. Using a popular on-line book catalog we discuss the effectiveness of our method over usual similarity based methods.

Fbref: Freeband/I-Share/P106v1.0

Where: SIGIR '08: Proceedings of the 31st Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, pp. 739-740, Singapore, 20-24 July, 2008.

Keywords: social tagging, synonyms

Optimizing Single-Term Queries Using a Personalized Markov Random Walk Over the Social Graph

Authors: Maarten Clements, Arjen P. de Vries, Marcel J.T. Reinders

Abstract: Social content systems contain enormous collections of unstructured user-generated content, annotated by the collaborative effort of regular Internet users. Tag-clouds have become popular interfaces that allow users to query the database by clicking relevant terms. However, these single click queries are often not expressive enough to effectively retrieve the desired content. Using both rating and tagging information we have created a personalized retrieval model that effectively integrates the personal user preference in the content ranking. The soft clustering effect of our random walk model allows a smooth integration of concepts indirectly related to the target user and the query tag. With collaborative annotations from a popular on-line book catalog, we show that our model outperforms standard tag-based retrieval. Both personalization and smoothing with closely related concepts significantly improve the content ranking. Our results indicate that individually created annotations are not semantically expressive enough to enable effective retrieval. Finally, we discuss the robustness of our model to well known linguistic problems like synonyms and homographs.

Fbref: Freeband/I-Share/P105v1.0

Where: Workshop on Exploiting Semantic Annotations in Information Retrieval (ESAIR) in ECIR'08, Glasgow, UK, March 2008.

Keywords: Social Networks, Content Retrieval, Collaborative Tagging, Rating, Personalization

Improving Motion Compensated Extrapolation for Distributed Video Coding

Authors: S. Borchert, R.P. Westerlaken, R. Klein Gunnewiek R.L. Lagendijk

Abstract: The ongoing research in Distributed Video Coding (DVC) for low complexity encoding is trying to shorten the substantial performance gap to well known state-of-the-art coders. We discuss the role of motion estimation and compensation with regard to the new constraints given by DVC. Furthermore we investigate different improvements of the introduced motion compensated extrapolation scheme as well as the reasons for choosing it. With these the quality of the side information can be enhanced. Among the improvements discussed in this paper are backward motion compensation, hole filling and bilateral filtering.

Fbref: Freeband/I-Share/P104v1.0

Where: Thirteenth Annual Conference of the Advanced School for Computing and Imaging, pp. 291-297, Heijen, The Netherlands, June 2007

Keywords: Distributed Source Coding, Video Compression, Motion Estimation/Compensation, 3DRS

Motion Compensated Prediction in Transform Domain Distributed Video Coding

Authors: S. Borchert, R.P. Westerlaken, R. Klein Gunnewiek R.L. Lagendijk

Abstract: The ongoing research in Distributed Video Coding (DVC) for low complexity encoding is trying to shorten the substantial performance gap to well known state-of-the-art coders. One way of reducing this gap is to improve the quality of the motion compensated prediction. In this paper we investigate which motion estimation method to apply in DVC, comparing possible methods to produce a motion compensated prediction. We use interpolation as well as extrapolation methods. Our results show that even with a very simple DCT scheme for the Wyner Ziv frames, extrapolation can outperform the widely used interpolation.

Fbref: Freeband/I-Share/P103v1.0

Where: Tenth International Workshop on Multimedia Signal Processing, pp. 332-336, Cairns, Queensland, Australia, October 2008

Keywords: Distributed Video Coding, side information, extrapolation

Motion Compensated Prediction in Distributed Video Coding

Authors: S. Borchert, R.P. Westerlaken, R. Klein Gunnewiek R.L. = Lagendijk

Abstract: The ongoing research in Distributed Video Coding (DVC) for low = complexity encoding is trying to shorten the substantial performance gap = to well known state-of-the-art coders. One of the reasons for this gap = is the motion estimation without the reference frame. In this paper we = look at what motion estimation to use. Furthermore we compare the two = possible methods to get a motion compensated prediction. These are = interpolation and extrapolation. Our results show that extrapolation = outperforms the widely used interpolation noticeably.

Fbref: Freeband/I-Share/P102v1.0

Where: Fourteenth Annual Conference of the Advanced School for Computing = and Imaging, pp. 230-234, Heijen, The Netherlands, June 2008.

Keywords: Distributed Source Coding, Video Compression, Motion = Estimation/Compensation, 3DRS

Analytical Model for Mesh-based P2PVoD

Authors: Y. Lu, J.J.D. Mol, F. Kuipers, P. van Mieghem

Abstract: Recently, there has been a growing interest in academic and commercial environments for Video-on-Demand (VoD) using Peer-to-Peer (P2P) technology. Unlike centralized solutions for VoD services, P2P technology lets the clients distribute video content among themselves. In this paper, we propose an analytical model for P2PVoD and we compare that model to a realistic P2PVoD simulator. With our model, parameters that affect the system performance can be observed, and the system stability can be investigated. Our model leads to design rules for achieving a good and stable system performance. This work is, to our knowledge, the first analytical work to model mesh-based P2PVoD.

Fbref: Freeband/I-Share/P101v1.0

Where: Proceedings IEEE International Symposium on Multimedia (ISM2008) Berkeley, CA, USA, Dec. 15-17, 2008.

Keywords: analytical model, peer-to-peer, video-on-demand

Offloading Servers with Collaborative Video on Demand

Authors: P. Garbacki, D.H.J. Epema, J.A. Pouwelse, and M.R. van Steen

Abstract: The peer-to-peer (P2P) paradigm provides a data distribution model that may be attractive for Video on Demand (VoD) as it allows to decrease the costs and to increase the scalability of video distribution. However, VoD is more challenging for P2P technology than file sharing or live streaming, and so, practically feasible VoD systems proposed to date rely on a backend server infrastructure as a fail-over solution. In this paper we investigate how the dependency on servers can be decreased by optimizing the video piece-selection strategy and by allowing multiple peers to form a collaboration for obtaining a single video. In a set of simulations of a trace-based system model we show that for systems such as YouTube the proposed optimizations would result in savings of as much as 70% of the server bandwidth. These simulation results confirm the conclusions of an analytical study of our optimizations, the essential part of which is also included in this paper.

Fbref: Freeband/I-Share/P100v1.0

Where: Proceedings Seventh Int'l Workshop on Peer-to-Peer Systems (IPTPS'08), Tampa Bay, FL, USA, Feb 25-26, 2008.

Keywords: peer-to-peer, video-on-demand, simulations

Community-Based Design Support

Authors: J. Daalhuizen, P. Badke-Schaub, J. Fokker

Abstract: Different approaches of design methodology that have been developed throughout the history of the design methods movement have produced many insights into the structure of the design process (Alexander, 1964; Simon, 1969; Schoen. 1983; Hubka and Eder, 1987; Pahl and Beitz. 1984; Roozenburg and Eekels, 1995). It seems however, that little of this accumulated knowledge is used in the daily practice of designing. The relation between design methodology and design practice is still weak (Cross, 1993; Achten et al. 2005). One reason might be that design methods are not addressing the designer's needs. And thus are not supporting the designer, with a specific task, to solve the problem at hand. (Badke- Schaub et al. 2005) The aim of this research project was to develop a solution for this problem: the concept of Community Based Design Support (CBDS). This concept, inspired by the online community platforms that are emerging on the internet, enables the integration of a personal, contextual, social and dynamic dimension in design methodology Based on the CBDS model a software platform was designed: Designflow. A prototype was built to test if the concept of CBDS can provide designers with efficient and effective design support.

Fbref: Freeband/I-Share/P99v1.0

Where: Proceedings Seventh International Symposium on Tools and Methods for Concurrent Engineering (TMCE 2008), Izmir, Turkey, 21-25 April, 2008.

Keywords: Design methodology, online support, virtual communities, inducing cooperation, wisdom of crowds

A Questionnaire-Based Study on Delayed Reciprocity in a P2P-TV System

Authors: J. Fokker, P. Westendorp, J. Pouwelse, H. de Ridder

Abstract: Using peer-to-peer (P2P) technology for distributing video files to many viewers simultaneously can only be successful if users cooperate voluntarily and massively. The current BitTorrent protocol enforces instantaneous bandwidth exchange within the context of one video file. To better exploit available resources for P2P-TV systems, such as our Tribler (www.tribler.org) software, we explore ways to induce user cooperation flexible over time and resources. The research is based on the social exchange theory and is done in two steps. First, the impact of social distance expressed in the degrees of separation (DoS) on the trust in reciprocity is investigated. Second, the DoS are combined with the kind of exchangeable resources typical for P2P-TV systems (i.e. injections and bandwidth) to find the influence of these variables on the accepted delay in reciprocity. The discussion will focus on the relation between trust in reciprocity and the accepted delay in reciprocity.

Fbref: Freeband/I-Share/P98v1.0

Where: Proceedings First International Conference on Designing Interactive User Experiences for TV and Video (uxTV'08), Silicon Valley, CA, USA, Oct 22-24, 2008.

Keywords: Social exchange theory, delayed reciprocity, peer-to-peer technology, user cooperation.

Tribler: A social-based peer-to-peer system

Authors: J.A. Pouwelse, P. Garbacki, J. Wang, A. Bakker, J. Yang, A. Iosup, D.H.J. Epema, M. Reinders, M. van Steen and H.J. Sips

Abstract: Most current peer-to-peer (P2P) file-sharing systems treat their users as anonymous, unrelated entities, and completely disregard any social relationships between them. However, social phenomena such as friendship and the existence of communities of users with similar tastes or interests may well be exploited in such systems in order to increase their usability and performance. In this paper we present a novel social-based P2P file-sharing paradigm that exploits social phenomena by maintaining social networks and using these in content discovery, content recommendation, and downloading. Based on this paradigm's main concepts such as taste buddies and friends, we have designed and implemented the TRIBLER P2P file-sharing system as a set of extensions to BitTorrent. We present and discuss the design of TRIBLER, and we show evidence that TRIBLER enables fast content discovery and recommendation at a low additional overhead, and a significant improvement in download performance.

Fbref: Freeband/I-Share/P97v1.0

Where: Concurrency and Computation: Practice and Experience

Keywords: tribler, bittorrent, cooperative download, semantic clustering

Broker Placement in Latency-Aware Peer-to-Peer Networks

Authors: P. Garbacki and D.H.J. Epema and M. van Steen

Abstract: In large peer-to-peer (P2P) overlay networks, nodes usually share resources to support all kinds of applications. In such networks, a subset of the nodes may assume the role of broker in order to act as intermediaries for finding the shared resources. When some notion of distance between nodes such as the internode latency is defined, a brokers may be responsible for maintaining information about resources shared by a group of nodes that are close to each other, with the set of nodes assigned to a broker being determined by the broker's location. In this paper, we present a broker-placement algorithm that finds a suitable location for a new broker when some broker is overloaded in such a way that some of the nodes are reassigned from the overloaded to the new broker. With latency as a metric, an overlay network can be embedded in an Euclidean space R^d, and our algorithm amounts to an optimization problem of selecting a suitable region in R^d for broker-placement, where a region represents equivalent broker locations. Our algorithm guarantees that if suitable regions exist, one of them will be found. The worst-case complexity of the algorithm is O(n^d^+^1) with n the number of nodes that may be assigned to the new broker, which is optimal up to a linear factor in n. We further show a simple optimization that brings down the complexity of the algorithm to a linear function of n in most of the cases. The linear complexity of the broker-placement algorithm is confirmed in a series of experiments on a real dataset. In addition, the performance of our broker-placement algorithm is compared to the performance of a naive approach, and it turns out that in a system with one million servers and one hundred brokers, our broker-placement algorithm is roughly 150 times more efficient.

Fbref: Freeband/I-Share/P96v1.0

Where: Computer Networks: The International Journal of Computer and Telecommunications Networking 52(8), Jun 2008, Elsevier North-Holland, Inc.

Keywords: Broker-placement, Content delivery network, Peer-to-peer, Resource brokerage

Pirates and Samaritans: A decade of measurements on peer production and their implications for net neutrality and copyright.

Authors: J.A. Pouwelse and P. Garbacki and D.H.J. Epema and H.J. Sips

Abstract: This study traces the evolution of commons-based peer production by a measurement-based analysis of case studies and discusses the impact of peer production on net neutrality and copyright law. The measurements include websites such as suprnova.org, youtube.com, and facebook.com, and the Peer-to-Peer (P2P) systems Kazaa, Bittorrent, and Tribler. The measurements show the two sides of peer production, the pirate side with free availability of Hollywood movies on these P2P systems and the Samaritan side exhibited by the quick joining of400,000+ people in a community to organize protests against events in Burma. The telecommunications and content industry are disrupted by this way of peer production. As a consequence, revenues of both industries are likely to suffer in the coming years. On the other hand, innovative P2P systems could win the battle on merit over classical distribution technologies. As a result, a continuation is expected of both legal actions against P2P and possible blocking actions of P2P traffic, violating net neutrality. It is argued that this hinders innovation and causes a large discrepancy between legal and user perspectives. A reform of copyright laws is clearly needed, otherwise they will be unenforceable around 2010.

Fbref: Freeband/I-Share/P95v1.0

Where: Telecommunications Policy 32 (2008), Elsevier, Ltd.

Keywords: peer-to-peer, net neutrality, copyright

Exploring the Acceptability of Delayed Reciprocity in Peer-to-Peer Networks

Authors: J.E. Fokker and H. de Ridder and P.H. Westendorp and J.A. Pouwelse

Abstract: Using Peer-to-Peer (P2P) technology for distributing Television programs to many viewers simultaneously can only be successful if users cooperate voluntarily and massively. The current BitTorrent protocol only enforces instantaneous bandwidth exchange within the context of one video file. We explore ways to induce user cooperation flexible over time and over type of resources. Essential resources for a P2P system are: bandwidth, injections, moderations, and appreciations. Social exchange theory is taken as a background for addressing the inducement of cooperation in a P2P-TV system called Tribler. This theory helps to explain how the acceptability of delayed reciprocity can be influenced by the specificity of the exchangeable resources and by the relationship types between individuals. This paper presents the results from a study among 36 participants about the acceptability of delayed reciprocity in a P2PTV system, under varying relationship types and specificity of exchangeable resources.

Fbref: Freeband/I-Share/P94v1.0

Where: Persuasive 2008 - The third international conference on persuasive technology, Oulu, Finland, June 2008.

Keywords: User communities, quantitative research, social issues, theories

Free-riding, Fairness, and Firewalls in P2P File-Sharing

Authors: J.J.D. Mol and J.A. Pouwelse and D.H.J. Epema and H.J. Sips

Abstract: Peer-to-peer file-sharing networks depend on peers uploading data to each other. Some peers, called free-riders, will not upload data unless there is an incentive to do so. Algorithms designed to prevent free-riding typically assume that connectivity is not a problem. However, on the Internet, a large fraction of the peers resides behind a firewall or NAT, making them unable to accept incoming connections. In this paper, we will prove that it is impossible to prevent free-riding when more than half of the peers are firewalled, and we will provide bounds on the sharing ratios (defined as the number of bytes uploaded divided by the number of bytes downloaded) of both firewalled and nonfirewalled peers. Firewall puncturing techniques are complex but can be used to connect two firewalled peers; we will provide a bound on their required effectiveness in order to achieve fairness. We confirm our theory by simulating individual BitTorrent swarms (sets of peers that download the same file), and show that the theoretical bounds can be met in systems with many firewalled peers. We have also collected statistics covering thousands of BitTorrent swarms in several communities, both open and closed; the latter ban peers if their sharing ratios drop below a certain treshhold. We found 45% of the peers to be firewalled in the closed communities, as opposed to 66% in the open communities, which correlates with our theory that to obtain fair sharing ratios for all peers, at most half of them can be behind firewalls.

Fbref: Freeband/I-Share/P93v1.0

Where: 8th IEEE International Conference on Peer-to-Peer Computing, Aachen, Germany, Sep. 2008.

Keywords: freeriding, bittorrent, fairness

Replication in Bandwidth Symmetric BitTorrent Networks

Authors: M. Meulpolder and D.H.J. Epema and H.J. Sips

Abstract: The popular and well-known BitTorrent peer-to-peer protocol offers fast file distribution in a highly scalable way. Several studies have investigated the properties of this protocol, mostly focusing on heterogeneous end-user environments such as the Internet, with asymmetric connections. In this paper however, we focus on the usage of the BitTorrent protocol in homogeneous local environments with symmetric bandwidth properties. Compared with a traditional client-server setup, the use of BitTorrent in such settings can offer huge benefits in performance and scalability, allowing bandwidth sharing and high speed file distribution. We aim to improve the performance of such networks with a novel mechanism for replication using so-called replicators, which replicate a subset of the files in the system. A mathematical model of the resulting Replicated BitTorrent is presented and validated by emulation. Furthermore, we present simulation results that provide insight in the performance of Replicated BitTorrent networks with dynamic peer arrivals and departures. The results show that Replicated BitTorrent significantly improves download times in local bandwidth-symmetric BitTorrent networks.

Fbref: Freeband/I-Share/P92v1.0

Where: Sixth International Workshop on Hot Topics in Peer-to-Peer Systems (Hot-P2P'09), Rome, Italy, May 2009.

Keywords: bittorrent, symmetric bandwidth

Scene Reconstruction using MRF Optimization with Image Content Adaptive Energy Functions

Authors: Ping Li and Rene Klein Gunnewiek and Peter H. N. de With

Abstract: Multi-view scene reconstruction from multiple uncalibrated images can be solved by two stages of processing: first, a sparse reconstruction using Structure From Motion (SFM), and second, a surface reconstruction using optimization of Markov random field (MRF). This paper focuses on the second step, assuming that a set of sparse feature points have been reconstructed and the cameras have been calibrated by SFM. The multi-view surface reconstruction is formulated as an image-based multi-labeling problem solved using MRF optimization via graph cut. First, we construct a 2D triangular mesh on the reference image, based on the image segmentation results provided by an existing segmentation process. By doing this, we expect that each triangle in the mesh is well aligned with the object boundaries, and a minimum number of triangles are generated to represent the 3D surface. Second, various objective and heuristic depth cues such as the slanting cue, are combined to define the local penalty and interaction energies. Third, these local energies are adapted to the local image content, based on the results from some simple content analysis techniques.

Fbref: Freeband/I-Share/P91v1.0

Where: Proc. Advanced Concepts for Intelligent Vision Systems, Lecture Notes in Computer Science, 2008

Keywords: surface reconstruction, 3D reconstruction, graph cut, MRF

Improving TCP/IP Performance over Last-hop Wireless Networks for Streaming Video Delivery

Authors: Igor Radovanovic, Richard Verhoeven, Johan Lukkien

Abstract: This paper discusses a link layer protocol that enhances performance of the Transmission Control Protocol (TCP) over a last-hop wireless network (LHWN) to make it more suitable for delivery of a live video with a short playout deadline. The presented protocol provides preference control of the transmission of video data within the network and it maximizes network goodput (the successfully transmitted amount of useful video data) by maximizing reliability of transmission for a given playout deadline and a varying digital bandwidth. The protocol makes use of the skip function in the TCP receiver [1], [2] to maximize end-to-end throughput of the connection at the expense of reducing full reliability. It can be implemented in a wireless access point to improve quality of the received live video over an Internet connection to an office or home. The main ideas of the protocol are: hide packet losses from the sender by performing local retransmissions based on the information from the video application and according to a certain scheduling policy, drop stale segments before they arrive at the receiver and prevent end-to-end retransmissions of segments received by the access point. The performance of the TCP Reno protocol [3] in combination with both the presented protocol and the skip function in the receiver is compared against the performance of TCP Reno [3], TCP-RTM [2], TCP Reno in combination with Snoop [4] and TCP-RTM in combination with Snoop. The results of simulations show improvement of network goodput across a wide range of packet-error rates.

Fbref: Freeband/I-Share/P90v1.0

Where: Accepted by the IEEE Transactions on CE, 2008.

Keywords: TCP/IP, last-hop wireless, live video

Virtual Community Management for Enabling P2P Services in the IMS Network

Authors: Igor Radovanovic, Johan Lukkien, Shudong Chen, Chris Molanus, Tanir Ozcelebi

Abstract: This paper addresses forming and management of a virtual community (VC) in the IP Multimedia Subsystem (IMS) network. A VC provides scope for mobile peer-to-peer (P2P) service sharing among end users and allows them control of sharing. The paper describes a number of services that enable forming and management of virtual communities and presents several service-oriented system architecture alternatives focusing on distribution of service access control and service discovery control between end users and operators as the owners of the IMS home-networks. Presented architecture alternatives are IMS compatible since they only introduce 5 additional services into the existing IMS architecture. A key service is an orchestrator that exposes new services composed of other services. A proofof- concept realization of the IMS architecture in which control of mobile service sharing is distributed among end users and operators is shown.

Fbref: Freeband/I-Share/P89v1.0

Where: Proc. of the IMSAA'08, Bangalore, India, December, 2008.

Keywords: virtual community, IMS network

Obtaining Resource Controllability in Service Cooperation Environments

Authors: S. Chen and J. J. Lukkien

Abstract: In a ubiquitous computing environment, devices host services that are accessed by anonymous users. This causes threats of resource abuse through malicious attacks or resource scarcity through unintentional excessive service invocations. In this paper, the secure resource control for service sharing is presented which depends on two basic functionalities: access control and soft-state management. Services are grouped into virtual communities for secure access. Service cooperation through external orchestration can only be done within a virtual community. Services can be activated/deactivated by a device management service running on their host devices. Real-time resource utilization of services for virtual community applications is monitored. Therefore, resources on a shared device can be protected from malicious use and become controllable for special quality of service provisioning.

Fbref: Freeband/I-Share/P88v1.0

Where: Proc. of the ACM MUM'08, Umea, Sweden, December, 2008.

Keywords: access control, resource control, service cooperation

Secure Resource Control in Service Oriented Applications

Authors: S. Chen and J. J. Lukkien

Abstract: This paper presents a secure resource control solution for service oriented applications. Through this, resources on a shared device can be protected from malicious abuse and become controllable for special QoS provisioning. Services are grouped into virtual communities and service access can only be done within the scope of a virtual community. Using soft-state management, services and their underlying resources are monitored by a novel device management service which runs on each device and can activate or deactivate hosted services.

Fbref: Freeband/I-Share/P87v1.0

Where: Proc. of the IEEE CCNC'09, Las Vegas, USA, January, 2009.

Keywords: resource control, access control, soft-state management, service oriented architecture

Context-Aware Resource Management for End-to-End QoS Provision in Service Oriented Applications

Authors: Shudong Chen, Johan Lukkien, Richard Verhoeven, Pim Vullers, Goran Petrovic

Abstract: Electronic devices admit the composition of applications from distributed services, like shared content, functionality and resources. Without proper management the quality of service (QoS) of this type of application is unacceptable. This paper presents a context-aware resource management middleware for service oriented applications, which aims to handle the inherent dynamics of services and the network. A way to manage the services and resources of a device is presented. Based on measurable and manageable services, this middleware can cope with changes of the environment of an application and optimize its overall performance. User desired application-oriented QoS is specified by an Orchestrator, which orchestrates the collaboration of distributed services to accomplish an application. A resource management service is built to support making dynamic service coordination decisions for the Orchestrator. For this, the resource management service gathers statistics of the required services and their resource utilization over a cross-layer monitoring model. An important aspect for keeping the privacy of the services and controlling the access to resources, all devices and services are organized in virtual communities. Only authenticated users are capable to access services and resources. A free view point 3D video streaming application is chosen to prove the feasibility of the proposed middleware.

Fbref: Freeband/I-Share/P86v1.0

Where: Proc. of the SUPE2008 workshop, in conjunction with IEEE GLOBECOM'08, New Orleans, USA, December, 2008.

Keywords: access control, resource management, service-oriented applications

Trust and Punishment

Authors: S. Etalle, J.I den Hartog, S. Marsh

Abstract: In recent years we have witnessed a great increase in the interest in Trust Management (TM) techniques both from the industrial and the academic sectors. The booming research has also determined a duality in the very definition of TM system which can lead to confusion. In one of the two categories of TM systems a great deal of work has yet to be done in advancing the inherently adaptive nature of trust. This position paper examines reasons for the success of TM, the two broad TM categories, and, for reputation-based TM, issues of `Regret Management' and accountability that are necessary enhancements on the road leading to much more sophisticated TM architectures.

Fbref: Freeband/I-Share/P85v1.0

Where: Proceedings of the 1st International Conference on Autonomic Computing and Communication Systems, Autonomics, Rome, Italy.

Keywords: trust management, regret management, accountability

On The Comparison Of Distributed Video Coding Using LDPC Codes On Bit Plane And Symbol Level

Authors: Ronald P. Westerlaken, Stefan Borchert, Rene Klein Gunnewiek, R.(Inald) L. Lagendijk

Abstract: Many distributed video coders are implemented using sophisticated error correction codes that use soft information (conditional probabilities) as a priori knowledge. This a priori information models the dependency behavior between the input data and side-information. In this paper we analyze both a symbol and bit plane based approach using LDPC codes. We show that a bit plane-based encoder has the same performance as a symbol-based coder, if an appropriate dependency model is chosen. We argue that due to a significant complexity reduction a bit plane-based coder is preferable over a symbol based approach.

Fbref: Freeband/I-Share/P84v1.0

Where: Thirteenth annual conference of the Advanced School for Computing and Imaging, Heijen, The Netherlands, June 2007

Keywords: distributed video coding, low density parity check codes, dependency models

Analyzing Symbol and Bit Plane-Based LDPC in Distributed Video Coding

Authors: R.P. Westerlaken, S. Borchert, R. Klein Gunnewiek, R.L. Lagendijk

Abstract: Many distributed video coders are implemented using sophisticated error correction codes that use soft information (conditional probabilities) as a priori knowledge. This a priori information models the dependency behavior between the input data and side-information. In this paper we analyze both a symbol and bit plane-based approach using LDPC codes. We show both theoretically and experimentally that a bit plane-based encoder has the same performance as a symbol-based coder, if an appropriate dependency model is chosen. We argue that due to a significant complexity reduction a bit planebased coder is preferable over a symbol-based approach.

Fbref: Freeband/I-Share/P83v1.0

Where: IEEE International Conference on Image Processing, San Antonio, Texas, USA, September 2007

Keywords: distributed video coding, low density parity check codes, dependency models

PuppetCast: A Secure Peer Sampling Protocol

Authors: A. Bakker and M. van Steen

Abstract: PuppetCast is a protocol for secure peer sampling in large-scale distributed systems. A peer sampling protocol continuously provides each node in the system with a uniform random sample of the node population, and is an important building block for gossip-based protocols for information dissemination, aggregation, load balancing and network management. Existing peer sampling protocols are either very vulnerable to attacks by malicious nodes, do not scale to large systems or provide only a static sample of the population. PuppetCast continues to operate when 50% (or more) of the nodes are acting maliciously, is shown to scale to systems of significant size and continuously provides new samples.

Fbref: Freeband/I-Share/P82v1.0

Where: Proceedings European Conference on Computer Network Defense (EC2ND'08), Dublin, Ireland, 11-12 December 2008.

Keywords: peer sampling service, security, gossip-based protocols

Trust Management in P2P Systems Using Standard TuLiP

Authors: M.R. Czenko, J.M. Doumen and S. Etalle

Abstract: In this paper we introduce Standard TuLiP - a new logic based Trust Management system. In Standard TuLiP, security decisions are based on security credentials, which can be issued by different entities and stored at different locations. Standard TuLiP directly supports the distributed credential storage by providing a sound and complete Lookup and Inference AlgoRithm (LIAR). In this paper we focus on (a) the language of Standard TuLiP and (b) on the practical considerations which arise when deploying the system. These include credential encoding, system architecture, system components and their functionality, and also the usability issues.

Fbref: Freeband/I-Share/P81v1.0

Where: Proceedings of IFIPTM 2008: Joint iTrust and PST Conferences on Privacy, Trust Management and Security, June 18-20, 2008, Trondheim, Norway.

Keywords: distributed credential storage, lookup and inference algorithm, trust management

2007

Proceedings of the WIC Midwintermeeting on IP-Television (IP-TV)

Authors: Peter H. N. de With and Goran Petrovic (editors)

Abstract: Digital video applications are widely accepted and the standards for digital video communication are under continuous development. The recent MPEG-4 AVC / H.264 video compression standard allows broadcast TV and HDTV transmission with roughly only half the bit rate of MPEG-2 coding. For this reason, this standard has been embraced for the upcoming HD-DVD and Bluray Disc systems. Similarly, the transmission of TV signals via the Internet can benefit from this new standard and enable widespread TV distribution via special networking strategies such as simulcasting, or peer-to-peer networking. Due to the unpredictable behavior of the Internet resulting from variable loads, special precautions for the compressed video signal must be taken to maintain sufficient robustness. Also the content providers will ask for information protection and digital rights management. Despite these technical aspects, TV transmission over the Internet may change conventional broadcasting models for content providers. Many interesting issues that will be dealt with by several prominent scientists and senior technical managers from both universities and the industry in Western Europe, who will present their work and will participate in the discussion.

Fbref: Freeband/I-Share/P80v1.0

Where: WIC Midwintermeeting on IP-Television, January 19, 2007, Eindhoven, The Netherlands, ISBN 978-90-6144-988-1.

Keywords: IPTV

Stereoscopic and Multiple-Perspective Video Streaming System

Authors: Goran Petrovic and Peter H. N. de With

Abstract: 3D-video systems allow a user to perceive depth in the viewed scene and to display the scene from arbitrary viewpoints interactively and on-demand. This paper presents a prototype implementation of a 3D-video streaming system using an IP network. The architecture of our streaming system is layered, where each information layer conveys a single coded video signal or coded scene-description data. We demonstrate the benefits of a layered architecture with two examples: (a) stereoscopic video streaming, (b) monoscopic video streaming with remote multiple-perspective rendering. Our implementation experiments confirm that prototyping 3D-video streaming systems is possible with today's software and hardware. Furthermore, the performance tests indicate that our system compares well to other systems presented in recent 3D-video streaming research.

Fbref: Freeband/I-Share/P79v1.0

Where: 28th Symposium on Information Theory in the Benelux, Enschede, The Netherlands, May 2007.

Keywords: Multi-view video, Stereoscopic video, Multimedia streaming.

A Distributed Delivery Model for 3D-Video Streams

Authors: Goran Petrovic, Dirk Farin and Peter H. N. de With

Abstract: 3D-video systems allow a user to perceive depth in the viewed scene and to interactively display the scene from multiple viewpoints. This paper presents an architecture for the scalable delivery of 3D-video streams over IP-networks, where we contribute in two aspects. First, we model 3D-video as a multi-stream application, where each stream (or layer) carries a single coded video signal or coded scene-description data. Second, we propose an end-to-end delivery model for 3D-video applications, which leverages a distributed system architecture to reduce the bandwidth and processing cost at the server and the end-hosts.

Fbref: Freeband/I-Share/P78v1.0

Where: International Conference on Immersive Telecommunications (IMMERSCOM), Bussolengo (Verona), Italy, October 2007.

Keywords: Multimedia streaming, 3D-video, Streaming-CDN.

A quality metric for use with frame-rate based bandwidth adaption algorithms

Authors: Matthias Krause, Michael v. Hartskamp, Emile Aarts

Abstract: Despite the growth in network capacity of wireless in-home networks, these networks often have insufficient capacity to support multiple simultaneous Audio/Video streams. Unpredictable behavior of these networks results in a drop of video quality for the end-user. A method for reducing the claim of an individual A/V stream on the network capacity is controlled frame dropping. However, controlled frame dropping will only be accepted if its effect on the quality that endusers experience is minimized. In this paper, we define an objective quality metric for frame dropping methods, to determine when frame dropping is not effective any more. The quality metric, a fraction between 0 and 1, is related to the characteristics of frame dropping. A quality level below 0,9 indicates that a detectable amount of frames has been dropped. A quality level above 0.98 indicates that no significant frame drops occurred recently. The metric is validated with simulations.

Fbref: Freeband/I-Share/P77v1.0

Where: 13th SPIE Human Vision and Electronic Imaging San Jose, Californica, USA, January 2008

Keywords: Temporal video quality, Frame dropping algorithm, Video streaming, Wireless

Content sharing and experience sharing with Web4CE

Authors: Lowet D., Shrubsole P.

Abstract: Social computing services that offer the ability to share content and experiences remotely have recently become very popular on the Internet. These services currently rely on desktop computing technologies to support features such as, video chat and presence information. Since many of these services fit well with the lean-back mode of Consumer Electronics (CE) devices and the family-oriented nature of the living room, this offers interesting opportunities for consumers and CE manufacturers. Based on Web4CE, an XHTML-based standard targeted for CE devices and recently adopted in the Digital Living Network Alliance, we have developed a sharing framework that enables content and experience sharing services on CE devices. This paper provides a short overview of our results.

Fbref: Freeband/I-Share/P76v1.0

Where: TICSP Adjunct Proceedings of EuroITV 2007.

Keywords: content sharing, web4ce

On Extrapolating Side Information in Distributed Video Coding

Authors: S. Borchert, R.P. Westerlaken, R. Klein Gunnewiek, R.L. Lagendijk

Abstract: The ongoing research in Distributed Video Coding (DVC) for low complexity encoding is trying to bridge the substantial performance gap to well known state-of-the-art coders. We introduce our true motion based extrapolation scheme and compare its performance to other state of the art systems in the field of DVC. The results of the extrapolation based approach display nearly the same performance as interpolation based ones. These results are also significantly better than the results from other state of the art extrapolation approaches. Furthermore we study the influence of the motion estimation part by investigating an interpolation approach, based on the same scheme. Finally, we study the losses incurred by using only past frames to represent the motion in the current one.

Fbref: Freeband/I-Share/P75v1.0

Where: 26th Picture Coding System, Lisbon, Portugal, November 2007.

Keywords: distributed video coding, side information

On the generation of side information for DVC

Authors: S. Borchert, R.P. Westerlaken, R. Klein Gunnewiek R.L. Lagendijk

Abstract: The ongoing research in Distributed Video Coding (DVC) for low complexity encoding is trying to shorten the substantial performance gap to well known state-of-the-art coders. We discuss the role of motion estimation and compensation with regard to the new constraints given by DVC. For this purpose we introduce two motion estimation schemes, one block based one and a global motion based one. In addition we investigate the possibility of giving the decoder additional statistical input based on these schemes. This input consists of an indication about the expected performance for certain regions. With this information the decoder can use more than one model. Previous work has shown that a reliable partitioning does indeed increase the performance. While the quality gain of using a global motion scheme over using a block based scheme is limited to only few cases, the results of the region indication are far more promising.

Fbref: Freeband/I-Share/P74v1.0

Where: Twenty-eigth Symposium on Infomation Theory in the Benelux, pp. 1141-148, May 2007.

Keywords: distributed video coding, side information

Contrast-invariant Feature Point Correspondence

Authors: Ping Li, Dirk Farin, Rene Klein Gunnewiek, Peter H. N. de With

Abstract: Most existing feature-matching methods utilize texture correlation for feature matching, which is usually sensitive to contrast changes. This paper proposes a new feature-point matching algorithm that does not rely on the image texture. Instead, only the smoothness assumption, which states that the displacement field in a neighborhood is coherent (smooth), is used. In the proposed method, the collected correspondences of a group of feature points within a neighborhood are efficiently determined such that the coherence measure of the displacement field in the neighborhood is maximized. The experimental results show that the proposed method is invariant to contrast changes and significantly outperforms the conventional block matching technique.

Fbref: Freeband/I-Share/P73v1.0

Where: Proc. IEEE Int. Conf. Acoustics, Speech and Signal Processing, vol. 1 p. I-477-I-480, April 2007

Keywords: Stereo, correspondence, feature point, contrast, feature matching

Descriptor-Free Smooth Feature-Point Matching for Images Separated by Small/Mid Baselines

Authors: Ping Li, Dirk Farin, Rene Klein Gunnewiek, Peter H. N. de With

Abstract: Most existing feature-point matching algorithms rely on photometric region descriptors to distinct and match feature points in two images. In this paper, we propose an efficient feature-point matching algorithm for finding point correspondences between two uncalibrated images separated by small or mid camera baselines. The proposed algorithm does not rely on photometric descriptors for matching. Instead, only the motion smoothness constraint is used, which states that the correspondence vectors within a small neighborhood usually have similar directions and magnitudes. The correspondences of feature points in a neighborhood are collectively determined in such a way that the smoothness of the local correspondence field is maximized. The smooth-ness constraint is self-contained in the correspondence field and is robust to the camera motion, scene structure, illumination, etc. This makes the entire point-matching process texture-independent, descriptor-free and robust. The experimental results show that the proposed method per-forms much better than the intensity-based block-matching technique, even when the image contrast varies clearly across images.

Fbref: Freeband/I-Share/P72v1.0

Where: Lecture Notes in Computer Science: Advanced Concepts for Intelligent Vision Systems, vol. p. , Aug 2007

Keywords: feature point, matching, stereo

Texture-independent Feature-point Matching (TIFM) from Motion Coherence

Authors: Ping Li, Dirk Farin, Rene Klein Gunnewiek, Peter H. N. de With

Abstract: This paper proposes a novel and efficient feature-point matching algorithm for finding point correspondences between two uncalibrated images. The striking feature of the proposed algorithm is that the algorithm is based on the motion coherence/smoothness constraint only, which states that neighboring features in an image tend to move coherently. In the algorithm, the correspondences of feature points in a neighborhood are collectively determined in a way such that the smoothness of the local motion field is maximized. The smoothness constraint does not rely on any image feature, and is self-contained in the motion field. It is robust to the camera motion, scene structure, illumination, etc. This makes the proposed algorithm texture-independent and robust. Experimental results show that the proposed method outperforms existing methods for feature-point tracking in image sequences.

Fbref: Freeband/I-Share/P71v1.0

Where: Proc. 8th Asian Conference on Computer Vision, vol. p. , Nov 2007

Keywords: feature point, matching, stereo, motion smoothness

Canning Spam in Wireless Gossip Networks

Authors: D. Gavidia and M. van Steen

Abstract: Once a problem associated only with email, spam is now affecting other media, such as instant messaging, blogs, newsgroups and mobile phone messaging. As wireless networks become more commonplace, we can expect that spam will find its way into upcoming wireless communication services. This paper studies the threat posed by malicious nodes inserting spam in a wireless network using gossiping as a method for information dissemination. We identify the security mechanisms needed to protect our gossip network against the proliferation of spam, reducing the problem to a matter of finding and removing corrupted messages. Finally, we propose a probabilistic method of integrity checking to contain the spread of spam which we evaluate through extensive simulations.

Fbref: Freeband/I-Share/P70v1.0

Where: Proceedings Fourth Int'l Conf. Wireless On-demand Network Systems & Services (WONS). Obergurgl, Austria, Jan 2007.

Keywords: spam, wireless networks, gossip

Enforcing Data Integrity in Very Large Ad Hoc Networks

Authors: D. Gavidia and M. van Steen

Abstract: Ad hoc networks rely on nodes forwarding each other’s packets, making trust and cooperation key issues for ensuring network performance. As long as all nodes in the network belong to the same organization and share the same goal (in military scenarios, for example), it can generally be expected that all nodes can be trusted. However, as wireless technology becomes more commonplace, we can foresee the appearance of very large, heterogeneous networks where the intentions of neighboring nodes are unknown. Without any security measures in place, any node is capable of compromising the integrity of the data it forwards. Our goal in this paper is to ensure the integrity of the data being disseminated without resorting to complex and expensive solutions. We achive this by discouraging malicious behavior in two ways: a) enforcing integrity checks close to the source and b) refusing to communicate with obviously malicious nodes. We find that by having nodes sample their traffic for corrupted messages, malicious nodes can be identified with high accuracy, in effect transforming our collection of nodes into a self-policing network.

Fbref: Freeband/I-Share/P69v1.0

Where: Proceedings 11th Int'l Conf. Mobile Data Mgt. Mannheim, Germany, May 2007.

Keywords: ad hoc networks, trust, data integrity

A Multi Phased Approach for Modeling and Analysis of the Bittorrent Protocol

Authors: Vivek Rai, Swaminathan Sivasubramanian, Sandjai Bhulai, Pawel Garbacki and Maarten van Steen

Abstract: BitTorrent is one of the most popular protocols for content distribution and accounts for more than 15% of the total Internet traffic. In this paper, we present an analytical model of the protocol. Our work differs from the previous works as it models the BitTorrent protocol specifically and not as a general file-swarming protocol. In our study, we observe that to accurately model the download process of a BitTorrent client, we need to split the download process into three phases. We validate our model using simulations and real-world traces. Using this model, we study the efficiency of the protocol based on various protocol-specific parameters such as the maximum number of connections and the peer set size. Furthermore, we study the relationship between changes in the system parameters and the stability of the protocol. Our model suggests that the stability of BitTorrent protocol depends heavily on the number of pieces a file is divided into and the arrival rate of clients to the network.

Fbref: Freeband/I-Share/P68v1.0

Where: 27th Int'l Conf.\ on Distributed Computing Systems, Toronto, Canada, Jun 2007.

Keywords: bittorrent, analytical model, protocol parameters, stability

Identifying Malicious Peers Before It's Too Late: A Decentralized Secure Peer Sampling Service

Authors: G.-P. Jesi, D. Hales and M. van Steen

Abstract: Many unstructured peer to peer (P2P) systems rely on a Peer Sampling Service (PSS) that returns randomly sampled nodes from the population comprising the system. PSS protocols are often implemented using "gossiping" approaches in which connected nodes exchange their links in a randomized way. However, such services can be defeated easily by malicious nodes executing "hub attacks" which distort the PSS such that all nodes in the network, ultimately, only gain access to malicious nodes. From this leading status - i.e. being a "hub" - the malicious nodes can affect the overlay in several ways, ranging from total network disruption to obtaining an application dependent advantage. We present a completely distributed defense against such attacks and give results from simulation experiments. The approach is generic as it is independent of the adopted PSS implementation.

Fbref: Freeband/I-Share/P67v1.0

Where: First Int'l Conf. Self-Adaptive & Self-Organizing Syst. Boston, MA, Jun 2007.

Keywords: peer-to-peer, overlay, security, gossiping.

Gossip-based Peer Sampling

Authors: M. Jelasity, S. Voulgaris, R. Guerraoui, A.-M. Kermarrec and M. van Steen

Abstract: Gossip-based communication protocols are appealing in large-scale distributed applications such as information dissemination, aggregation, and overlay topology management. This paper factors out a fundamental mechanism at the heart of all these protocols: the peer-sampling service. In short, this service provides every node with peers to gossip with. We promote this service to the level of a first-class abstraction of a large-scale distributed system, similar to a name service being a first-class abstraction of a local-area system. We present a generic framework to implement a peer-sampling service in a decentralized manner by constructing and maintaining dynamic unstructured overlays through gossiping membership information itself. Our framework generalizes existing approaches and makes it easy to discover new ones. We use this framework to empirically explore and compare several implementations of the peer-sampling service. Through extensive simulation experiments we show that—although all protocols provide a good quality uniform random stream of peers to each node locally—traditional theoretical assumptions about the randomness of the unstructured overlays as a whole do not hold in any of the instances. We also show that different design decisions result in severe differences from the point of view of two crucial aspects: load balancing and fault tolerance. Our simulations are validated by means of a wide-area implementation.

Fbref: Freeband/I-Share/P66v1.0

Where: ACM Trans. Comp. Syst. 25(3), Aug 2007.

Keywords: gossip-based protocols, epidemic protocols, peer sampling service

Hybrid Dissemination: Adding Determinism to Probabilistic Multicasting in Large-Scale P2P Systems

Authors: S. Voulgaris and M. van Steen

Abstract: Epidemic protocols have demonstrated remarkable scalability and robustness in disseminating information on internet-scale, dynamic P2P systems. However, popular instances of such protocols suffer from a number of significant drawbacks, such as increased message overhead in push-based systems, or low dissemination speed in pull-based ones. In this paper we study push-based epidemic dissemination algorithms, in terms of hit ratio, communication overhead, dissemination speed, and resilience to failures and node churn. We devise a hybrid push-based dissemination algorithm, combining probabilistic with deterministic properties, which limits message overhead to an order of magnitude lower than that of the purely probabilistic dissemination model, while retaining strong probabilistic guarantees for complete dissemination of messages. Our extensive experimentation shows that our proposed algorithm outperforms that model both in static and dynamic network scenarios, as well as in the face of large-scale catastrophic failures. Moreover, the proposed algorithm distributes the dissemination load uniformly on all participating nodes.

Fbref: Freeband/I-Share/P65v1.0

Where: Middleware 2007,Irvine, CA, Oct 2007.

Keywords: epidemic/gossip protocols, information dissemination, peer-to-peer

Proactive Gossip-Based Management of Semantic Overlay Networks

Authors: S. Voulgaris, M. van Steen and K. Iwanicki

Abstract: Much research on content-based P2P searching for file-sharing applications has focused on exploiting semantic relations between peers to facilitate searching. Current methods suggest reactive ways to manage semantic relations: they rely on the usage of the underlying search mechanism, and infer semantic relationships based on the queries placed and the corresponding replies received. In this paper we follow a different approach, proposing a proactive method to build a semantic overlay. Our method is based on an epidemic protocol that clusters peers with similar content. Peer clustering is done in a completely implicit way, that is, without requiring the user to specify preferences or to characterize the content of files being shared. In our approach, each node maintains a small list of semantically optimal peers. Our simulation studies show that such a list is highly effective when searching files. The construction of this list through gossiping is efficient and robust, even in the presence of changes in the network.

Fbref: Freeband/I-Share/P64v1.0

Where: Conc. & Comput.: Prac. & Exp. 19(17), December 2007

Keywords: peer-to-peer search networks, gossip-based protocols, semantic overlay networks

The Orchard Algorithm: Building Mulicast Trees for P2P Video Multicasting without Free-Riding

Authors: J.D. Mol and D.H.J. Epema and H.J. Sips

Abstract: The main purpose of many current peer-to-peer (P2P) networks is off-line file sharing. However, a potentially very promising use of such networks is to share video streams (e.g., TV programs) in real time. In order to do so, the peers in a P2P network who are interested in the same video stream may employ Application Level Multicasting (ALM). In existing P2P networks, peers may exhibit behavior which is problematic for ALM: they are not always willing to donate resources (free-riding), and they may arrive and depart at a high rate (churn). In this paper we propose the Orchard algorithm for creating and maintaining ALM trees in P2P networks, which deals with both these problems. By employing a technique called Multiple Description Coding, we split a video stream into several substreams. Orchard creates a dynamic spanning tree for each of these substreams in such a way that in the resulting forest, no peer has to forward more substreams than it receives. Based on an analysis of the expected performance of Orchard and on experiments in a real system, we find that Orchard is capable of maintaining a multicast forest, even when peers join and leave the forest at a high rate.

Fbref: Freeband/I-Share/P63v1.0

Where: IEEE Transactions on Multimedia, Vol. 9, pp. 1593-1604, 2007

Keywords: distributed algorithms, free-riding, multicast channels, multiple description coding, peer-to-peer

Optimizing Peer Relationships in a Super-Peer Network

Authors: P. Garbacki and D.H.J. Epema and M. van Steen

Abstract: Super-peer architectures exploit the heterogeneity of nodes in a P2P network by assigning additional responsibilities to higher-capacity nodes. In the design of a super-peer network for file sharing, several issues have to be addressed: how client peers are related to super-peers, how super-peers locate files, how the load is balanced among the super-peers, and how the system deals with node failures. In this paper we introduce a self-organizing super-peer network architecture (SOSPNet) that solves these issues in a fully decentralized manner. SOSPNet maintains a super-peer network topology that reflects the semantic similarity of peers sharing content interests. Super-peers maintain semantic caches of pointers to files which are requested by peers with similar interests. Client peers, on the other hand, dynamically select super-peers offering the best search performance. We show how this simple approach can be employed not only to optimize searching, but also to solve generally difficult problems encountered in P2P architectures such as load balancing and fault tolerance. We evaluate SOSPNet using a model of the semantic structure derived from the 8-month traces of two large file-sharing communities. The obtained results indicate that SOSPNet achieves close-to-optimal file search performance, quickly adjusts to changes in the environment (node joins and leaves), survives even catastrophic node failures, and efficiently distributes the system load taking into account peer capacities.

Fbref: Freeband/I-Share/P62v1.0

Where: 27th International Conference on Distributed Computing Systems (ICDCS 2007), 2007.

Keywords: peer-to-peer, super-peer architectures, semantic clustering, self-organizing systems

An Amortized Tit-For-Tat Protocol for Exchanging Bandwidth instead of Content in P2P Networks

Authors: P. Garbacki and D.H.J. Epema and M. van Steen

Abstract: Incentives for resource sharing are crucial for the proper operation of P2P networks. The principle of the incentive mechanisms in current content sharing P2P networks such as BitTorrent is to have peers exchange content of mutual interest. As a consequence, a peer can actively participate in the system only if it shares content that is of immediate interest to other peers. In this paper we propose to lift this restriction by using bandwidth rather than content as the resource upon which incentives are based. Bandwidth, in contrast to content, is independent of peer interests and so can be exchanged between any two peers. We present the design of a protocol called amortized tit-for-tat (ATFT) based on the bandwidth-exchange concept. This protocol defines mechanisms for bandwidth exchange corresponding to those in BitTorrent for content exchange, in particular for finding bandwidth borrowers that amortize the bandwidth borrowed in the past with their currently idle bandwidth. In addition to the formally proven incentives for bandwidth contributions, ATFT provides natural solutions to the problems of peer bootstrapping, seeding incentive, peer link asymmetry, and anonymity, which have previously been addressed with much more complex designs. Experiments with a real-world dataset confirm that ATFT is efficient in enforcing bandwidth contributions and results in download performance better than provided by incentive mechanisms based on content exchange.

Fbref: Freeband/I-Share/P61v1.0

Where: 1st IEEE International Conference on Self-Adaptive and Self-Organizing Systems (SASO 2007), pp. 119-128, IEEE Computer Society Press, 2007

Keywords: peer-to-peer, data transfer protocols, incentives, bandwidth exchange

A service-oriented virtual community overlay network for secure external service orchestration

Authors: Shudong Chen, Johan Lukkien

Abstract: The Service Oriented Architecture (SOA) is used extensively in ubiquitous computing environments. Using external service orchestration, services can be composed into applications. Since cooperation takes place between services that are scattered over the Internet and belong to different parties, there is a growing need to protect the ownership of service providers and keep the security of communication messages in service composition. This paper shows the details of a service-oriented virtual community overlay network designed for secure external service orchestration. It can also provide contracted QoS guarantees that will definitely affect the overall performance of ubiquitous applications. Further, it highlights the working principle of access control policies as well as a service behavior monitoring mechanism using an example scenario.

Fbref: Freeband/I-Share/P60v1.0

Where: In the proceedings of the 5th International Workshop on Middleware for Pervasive and Ad-Hoc Computing. Newport Beach, California, USA, December 2007.

Keywords: Service-oriented virtual community, Security, Service orchestration

VICSDA: Using Virtual Communities to Secure Service Discovery and Access.

Authors: Shudong Chen, Johan Lukkien, Igor Radovanovic, et al.

Abstract: Service Oriented Architecture (SOA) is emerging as an enabling technology for sharing distributed heterogeneous resources on the network. Consequently, securing services is an increasing concern. Research issues include privacy protection for service providers, transparent access control for service consumers, secure service discovery and composition. In this paper, we present an access control approach which uses virtual communities to secure service discovery and access (VICSDA). Services grouped in virtual communities can only be discovered and accessed by authenticated community members. Meanwhile, services are autonomous to define their local access control policy. Moreover, behavior of these autonomous services is monitored in order to guarantee a better QoS provision. Using a virtual community overlay network on top of a SOA infrastructure, VICSDA can provide authentication, message confidentiality and integrity to secure service discovery and access. Better application performance can be achieved through VICSDA. We integrated VICSDA with a 3D video streaming application. This example provides us with some initial evidence that VICSDA is a viable solution to our target problems.

Fbref: Freeband/I-Share/P59v1.0

Where: In the proceedings of the Fourth International Conference on Heterogeneous Networking for Quality, Reliability, Security and Robustness. Vancouver, Canada, August, 2007.

Keywords: Security, Service discovery and access, Virtual community, 3D video streaming

Virtual Community Based Secure Service Discovery and Access for 3D Video Steaming Applications

Authors: Shudong Chen, Igor Radovanovic, Johan Lukkien, et al.

Abstract: The Freeband I-Share project aims to define the mechanisms for trust, willingness, resource discovery and sharing mechanisms in virtual communities. To improve the secure and performance of a 3D video streaming application, which is a research vehicle of the I-Share project, we propose a virtual community based access control approach for secure service discovery and access (VICSDA) which groups services in virtual communities and only grants authenticated community members to discover and access these community services. There are two main contributions associated with this approach. First, different from most of the other access control approaches it adopts a dual access control mechanism which allows community services to define their local access control policy besides following the community membership policy. Second, behavior of these community services is monitored in order to guarantee a better QoS provision. Using this approach, the 3D video streaming application can be guaranteed with authentication and message confidentiality through the dual secure service discovery and access mechanism. Better application performance can also be achieved through the community member behavior audit.

Fbref: Freeband/I-Share/P58v1.0

Where: In the Proceeding of the International Workshop on Multimedia Content Analysis and Mining International Workshop on Multimedia Content Analysis and Mining. Weihai, China, June 2007.

Keywords: 3D video streaming, virtual community, access control

Improving TCP/IP Performance over Last-hop Wireless Networks for Streaming Video Delivery

Authors: Igor Radovanovic, Richard Verhoeven, Johan Lukkien

Abstract: This paper discusses a protocol for delivery of streaming video with a short play-out deadline over a lasthop wireless network, which trades reliability for latency. This protocol could be implemented in the wireless access point to improve the quality of the received streaming video over an Internet connection to an office or home. The main ideas of the protocols are twofold: 1) across the wireless link: perform local retransmissions and drop any stale packets; 2) across the entire source-destination path: hide duplicated acknowledgements from the sender to avoid retransmissions. In addition, the protocol takes advantage of application level framing and acknowledges missing transport layer segments with expired play-out deadlines. Although several existing protocols partially solve the problem of streaming video delivery in this particular context, either by improving the performance of the wireless link or by dropping the stale packets, to our best knowledge none of the protocols solves the complete problem. The performance of our protocol is compared against the performance of the Snoop, TCP RTM, combined with Snoop and TCP RTM protocols, as well as TCP Reno. The results of simulations show a manyfold improvement of the goodput across a wide range of packet-error rates.

Fbref: Freeband/I-Share/P57v1.0

Where: In Digest of technical papers of the International Conference on Consumer Electronics, 2007, ICCE 2007. Las Vegas, USA, January 2007.

Psychological backgrounds for inducing cooperation in peer-to-peer television

Authors: Fokker,J.E., H.de Ridder, P.H.Westendorp, J.A.Pouwelse

Abstract: Television and the Internet have proven to be a popular combination for both broadcasters and viewers. Because of this popular ity they are increasingly facing the consequences of central bottlenecks, which could be overcome by taking a different approach: Peer-to-Peer (P2P) technology. P2P systems can only be successful with as much cooperation among as many users as possible. We explain how this cooperation is hard to enforce, and how induci ng it might be more successful. This paper lists relevant psychological backgrou nds that can be used to induce this cooperation, along with possible application s for our system called Peer-to-Peer Television (P2P-TV).

Fbref: Freeband/I-Share/P56v1.0

Where: EuroITV'07 conference, Amsterdam, May 24-25, 2007

Keywords: Peer-to-peer technology, inducing cooperation, altruism, (social) psychological theories.

Remote User Experience Testing of Peer-to-Peer Television Systems: A Pilot Study on Tribler

Authors: Fokker, J.E., A.P.O.S.Vermeeren, H.de Ridder

Abstract: Peer-to-peer television (P2P-TV) systems like Tribler depend on the inducement of massive cooperation among users. In Tribler, knowledge from (social) psychology on altruistic behavior is used for developing cooperation inducing mechanisms. Aiming to verify the effectiveness of these mechanisms, this paper presents the first remote user experience test of the current version of Tribler. The test focused on four usage-related issues: downloading, seeding, moderation, and social reach. It was found that the current users are mainly interested in downloading. Users hardly kept files available for others to download (`seeding') and performed few actions in relation to maintaining their own network of friends (`social reach') or to performing quality control of content and metadata (`moderation').

Fbref: Freeband/I-Share/P55v1.0

Where: EuroITV'07 conference (Work in Progress track), Amsterdam, May 23, 2007

Keywords: user experience testing, remote testing, peer-to-peer television

A Demonstration of Tribler: Peer-to-Peer Television

Authors: Fokker J.E., M.ten Brinke, H.de Ridder, P.H.Westendop, J.A.Pouwelse

Abstract: The success of Peer-to-Peer Television (P2P- TV) systems depends on the inducement of users to cooperate massively and voluntarily. To operationalize our proposed applications of incentives based on psychological backgrounds, we discuss a demonstration of our own P2P-TV system called Tribler. It is a system for downloading, video-on-demand (VoD), and live streaming of Television content. This paper discusses the demonstration of Tribler version 4.0 as the first operationalization of relevant psychological backgrounds.

Fbref: Freeband/I-Share/P54v1.0

Where: EuroITV'07 conference (Demo Session), Amsterdam, May 24-25, 2007

Keywords: tribler, peer-to-peer television, inducing cooperation

Inducing human cooperation in peer-to-peer television systems

Authors: Fokker, J.E., H.de Ridder, P.H.Westendorp, J.A.Pouwelse

Abstract: Peer-to-Peer (P2P) technology is regard ed as a good alternative for client-server architectures in the massive distribu tion of large video files and television streams to a large number of users. But the success of P2P systems depends on the cooperation of users. This paper disc usses a PhD project on the inducement of cooperation in P2P-TV systems. It prese nts relevant mechanisms from state-of-the-art websites and psychological backgro unds. These mechanisms will be applied to the user interface of our P2P-TV system called Tribler and evaluated in a series of remote user experience tests.

Fbref: Freeband/I-Share/P53v1.0

Where: EuroITV'07 conference (Doctoral Consortium), Amsterdam, May 24-25, 2007

Keywords: inducing cooperation, peer-to-peer television, user interface design

Personalization on a peer-to-peer television system

Authors: Wang, J., J.A.Pouwelse, J.E.Fokker, A.P.de Vries, M.J.T.Reinders

Abstract: We introduce personalization on Tribler, a peer-to-peer (P2P) television system. Personalization allows users to browse programs much more efficiently according to their taste. It also enables to build social networks that can improve the performance of current P2P systems considerably, by increasing content availability, trust and the realization of proper incentives to exchange content. This paper presents a novel scheme, called BuddyCast, that builds such a social network for a user by exchanging user interest profiles using exploitation and exploration principles. Additionally, we show how the interest of a user in TV programs can be predicted from the zapping behavior by the introduced useritem relevance models, thereby avoiding the explicit rating of TV programs. Further, we present how the social network of a user can be used to realize a truly distributed recommendation of TV programs. Finally, we demonstrate a novel user interface for the personalized peer-to-peer television system that encompasses a personalized tag-based navigation to browse the available distributed content. The user interface also visualizes the social network of a user, thereby increasing community feeling which increases trust amongst users and within available content and creates incentives of to exchange content within the community.

Fbref: Freeband/I-Share/P52v1.0

Where: Multimedia Tools and Applications, Volume 36, Numbers 1-2 / January, 2008.

Keywords: Tribler , BuddyCast , Peer-to-peer (P2P) television system , Personalization , Collaborative filtering , Recommender system

Tag-Based Navigation for Peer-to-Peer Wikipedia

Authors: Fokker, J.E., J.A. Pouwelse, W. Buntine, H. de Ridder, P.H. Westendorp

Abstract: This paper introduces P2P Wikipedia, a prototype of a pers onalized tag-based navigation system for Wikipedia multimedia content. It is the first Peer-to-Peer (P2P) file sharing system able to deal with large files like movies, music , and sofware, but that is also scalable to HTML content. The pap er explains why, when, and how tag-based navigation can augment traditional keyw ord searching for Wikipedia.org, and why cooperation is needed from the users to do so. It also describes how excessive and costly bandwidth problem can be solv ed by using P2P technology, which accumulates distributed resources and can also be applied to web content.

Fbref: Freeband/I-Share/P51v1.0

Where: Chapter in "P2P networks" (Icfai's Professional Reference Book)

Keywords: tag-based navigation, peer-to-peer, wikipedia official url: http://www.books.iupindia.org/newarticle.asp?isbn=81-314-0890-6&bookid=IB1101414

Evaluation of a platform for automated, remote, in-situ user experience measurement

Authors: A. Vermeeren,J. Fokker, J. Kort

Abstract: A preliminary version of a platform for automated, remote, in-sit u user experience measurement called TUMCAT was evaluated. The use of peer-to-pe er software was monitored with it during five weeks and subjective data were gat hered with the through experience sampling. Findings from two alternative ways o f evaluating the software were compared to findings yielded by TUMCAT. The resul ts of the comparison clearly show how findings from the different evaluations co mplement each other. Suggestions are formulated on how these findings can be use d to improve TUMCAT.

Fbref: Freeband/I-Share/P50v1.0

Where: Proceedings of the British HCI conference 2007, Lancaster, UK, 3 - 7 September 2007.

Keywords: User experience measurement, automated evaluation, automated usage analysis, event logging, experience sampling, context measurement.

Evaluation of Neighbourhood Selection Methods in Decentralized Recommendation Systems

Authors: Maarten Clements, Arjen P. de Vries, Johan A. Pouwelse, Jun Wang, Marcel J.T. Reinders

Abstract: Recommendation systems are important in social networks that allow the injection of user-generated content and let users indicate their references towards the content introduced by others. Considering the increase of usage of these collaborative systems, it seems only a matter of time before the current centralized systems will be replaced by decentralized solutions. However, current collaborative filtering systems assume that recommendations can be based on the entire data collection in the network. This work evaluates the performance of user-based collaborative filtering systems when only partial knowledge about the network is available at an end-user's computer. We propose a utility model that combines three important aspects of network users (similarity, confidence and usefulness) in order to create a semantic overlay network optimized for autonomous content recommendations. We compare different similarity functions on the most common dataset in collaborative filtering and we show the influence of the confidence and usefulness parameters on both dense and sparse data. We find that the commonly used similarity function results in sub-optimal performance when used as updating criterion for locally stored rating profiles. We show that taking into account the level of confidence in the computed similarity can greatly improve recommendation accuracy, especially when a small user neighborhood is selected. Also, conventional methods select many users that cannot contribute to the recommendation, because they have rated too few items. The usefulness parameter that we introduce compensates for this problem, so that even a small local cache in very sparse data provides valuable recommendations.

Fbref: Freeband/I-Share/P49v1.0

Where: Workshop on Large Scale Distributed Systems for Information Retrieval (LSDS-IR)

Keywords: Distributed Information Retrieval, Social Networks, Collaborative Filtering, Recommendation, Similarity

Personalization of social media

Authors: Maarten Clements

Abstract: This article describes a framework that captures collaborative tagging systems, and derives from it an overview of user tasks that qualify for personalization in such a system. Major research areas have focused on some of these tasks, but we identify many more opportunities. We propose a collaborative model that combines collaborative filtering and information retrieval techniques in order to assists the user to achieve these tasks. Based only on the user's tags, this personalization model assumes that a user's tags identify this user's taste. Because many users do not only tag the content that matches their taste, we propose an evaluating experiment that shows if rating information can be used to adjust the users' taste profiles. This experiment is one of the steps to advance to a completely personalized model, integrating user preference, content annotations and people relations.

Fbref: Freeband/I-Share/P48v1.0

Where: BCS IRSG Symposium: Future directions in Information Access 2007

Keywords: Social Media, Personalization, Collaborative Tagging, Rating, Collaborative Filtering, Information Retrieval

How robust are gossip-based communication protocols?

Authors: L. Alvisi, J. M. Doumen, R. Guerraoui, B. Koldehofe, H. Li, R. van Renesse, G. Tredan

Abstract: Gossip-based communication protocols are often touted as being robust. Not surprisingly, such a claim relies on assumptions under which gossip protocols are supposed to operate. In this paper, we discuss and in some cases expose some of these assumptions and discuss how sensitive the robustness of gossip is to these assumptions. This analysis gives rise to a collection of new research challenges.

Fbref: Freeband/I-Share/P47v1.0

Where: ACM Operating Systems Review 41(5), October 2007

Keywords: gossip-based protocols, robustness

Core TuLiP - Logic Programming for Trust Management

Authors: M. R. Czenko and S. Etalle

Abstract: We propose CoreTuLiP - the core of a trust management language based on Logic Programming. CoreTuLiP is based on a subset of moded logic programming, but enjoys the features of TM languages such as RT; in particular clauses are issued by different authorities and stored in a distributed manner. We present a lookup and inference algorithm which we prove to be correct and complete w.r.t. the declarative semantics. CoreTuLiP enjoys uniform syntax and the well-established semantics and is expressive enough to model scenarios which are hard to deal with in RT.

Fbref: Freeband/I-Share/P46v1.0

Where: Proceedings of the 23rd International Conference on Logic Programming, ICLP 2007, Porto, Portugal, October 2007.

Keywords: CoreTuLiP, trust management language

Key Management Building Blocks for Wireless Sensor Networks

Authors: Y. W. Law and J. M. Doumen and M. Palaniswami

Abstract: Cryptography is the means to ensure data confidentiality, integrity and authentication in wireless sensor networks (WSNs). To use cryptography effectively however, the cryptographic keys need to be managed properly. First of all, the necessary keys need to be distributed to the nodes before the nodes are deployed in the field, in such a way that any two or more nodes that need to communicate securely can establish a session key. Then, the session keys need to be refreshed from time to time to prevent birthday attacks. Finally, in case any of the nodes is found to be compromised, the key ring of the compromised node needs to be revoked and some or all of the compromised keys might need to be replaced. These processes, together with the policies and techniques needed to support them, are called key management. The facts that WSNs (1) are generally not tamper-resistant; (2) operate unattended; (3) communicate in an open medium; (4) have no fixed infrastructure and pre-configured topology; (5) have severe hardware and resource constraints, present unique challenges to key management. In this article, we explore techniques for meeting these challenges. What distinguishes our approach from a routine literature survey is that, instead of comparing various known schemes, we set out to identify the basic cryptographic principles, or building blocks that will allow practitioners to set up their own key management framework using these building blocks.

Fbref: Freeband/I-Share/P45v1.0

Where: IEEE communications magazine (accepted for publication)

Keywords: key management, wireless sensor networks

Trust Management, Proceedings of IFIPTM 2007: Joint iTrust and PST Conferences on Privacy, Trust Management and Security

Authors: S. Etalle and S. Marsh

Abstract: Editors.

Fbref: Freeband/I-Share/P44v1.0

Where: IFIPTM 2007: July 30-August 2, 2007, New Brunswick, Canada

Keywords: trust management official url: http://dx.doi.org/10.1007/978-0-387-73655-6

An Introduction to the Role Based Trust Management Framework RT

Authors: M. R. Czenko and S. Etalle and D. Li and W. H. Winsborough

Abstract: Trust Management (TM) is a novel flexible approach to access control in distributed systems, where the access control decisions are based on the policy statements, called credentials, made by different principals and stored in a distributed manner. In this chapter we present an introduction to TM focusing on the role-based trust-management framework RT. In particular, we focus on RT0, the simplest representative of the RT family, and we describe in detail its syntax and semantics. We also present the solutions to the problem of credential discovery in distributed environments.

Fbref: Freeband/I-Share/P43v1.0

Where: Foundations of Security Analysis and Design IV -- FOSAD 2006/2007 Tutorial Lectures. Springer Verlag, Berlin July 2007

Keywords: trust management, role-based

A Posteriori Compliance Control

Authors: S. Etalle and W. H. Winsborough

Abstract: While preventative policy enforcement mechanisms can provide theoretical guarantees that policy is correctly enforced, they have limitations in practice. They are inflexible when unanticipated circumstances arise, and most are either inflexible with respect to the policies they can enforce or incapable of continuing to enforce policies on data objects as they move from one system to another. In this paper we propose an approach to enforcing policies not by preventing unauthorized use, but rather by deterring it. We believe this approach is complementary to preventative policy enforcement. We call our approach APPLE for A-Posteriori PoLicy Enforcement. We introduce APPLE Core, a logical framework for using logs to verify that actions taken by the system were authorized. A trust management system is used to ensure that data objects are provided only to users operating on auditable systems who are subject to penalty should they be found in violation. This combination of audit and accountability provides a deterrence that strongly encourages trustworthy behavior, thereby allowing a high level of assurance of end-to-end policy enforcement.

Fbref: Freeband/I-Share/P42v1.0

Where: 12th ACM Symposium on Access Control Models and Technologies (SACMAT), Nice, France, June 2007.

Keywords: compliance control

2006

Asymmetric Multiple Description Coding using Layered Coding and Lateral Error Correction

Authors: Jacco R. Taal and Inald L. Lagendijk

Abstract: In this paper we present a method for Asymmetric Multiple Description Coding (AMDC) using Reed Solomon Channel Codes and Layered Coding. Asymmetric MDC can be used when channel conditions are not uniform. For instance peer-to-peer networks or heterogeneous (wired and wireless) networks may offer different channels with different bandwidths and loss characteristics. The AMDC encoder can be designed to fit these network conditions and in many cases outperforms single description coding, symmetric MDC, layered coding and in some cases layered coding with unequal error protections. (A)MDC exploits the diversity offered by multiple (parallel) channels without increasing the delay. In general, optimizing the design and rate allocation for the AMDC method is hard. In this paper we first introduce the general framework of AMDC and give some examples for which the AMDC outperforms other methods.

Fbref: Freeband/I-Share/P41v1.0

Where: Werkgemeenschap Informatie en Communicatie Theory, 2006.

Keywords: Asymmetric Multiple Description Coding

Optimized Video Streaming over 802.11 by Cross-layer Signaling

Authors: Ivaylo Haratcherev and Jacco R. Taal and Koen Langendoen and R.(Inald) Lagendijk and Henk Sips

Abstract: Seamless video streaming over wireless links imposes strong demands on video codecs and the underlying network. It is not sufficient that only the video codec or only the radio adapts to changes in the wireless link quality; efforts should be applied in both layers, and - if possible - synchronized. Also, the disturbing effect of possible background traffic over the same shared medium has to be taken into account. In this article we present a communication architecture for video streaming over 802.11 that is capable of adapting to changes in the link quality and sharing of the wireless channel in various use scenarios. Experimental results show that substantial improvements in the quality of the video can be obtained by applying link adaptation and cross-layer signaling techniques.

Fbref: Freeband/I-Share/P40v1.0

Where: IEEE Communications Magazine, vol. 44, no. 1, pp. 115--121, 1 2006.

Keywords: video streaming, wireless networks, cross-layer signaling

Hybrid Temporal-SNR Multiple Description Coding for Peer-to-Peer Television

Authors: Jacco R. Taal and R.(Inald) L. Lagendijk

Abstract: In this paper we present Hybrid Temporal/SNR Scalable Multiple Description Coding. For efficient Peer-to-Peer streaming more than two descriptions are required. In our P2P-TV video streaming network, we also need scalability and error resilience. To increase the number of descriptions we use SNR enhancement layers with channel codes (MD-FEC). The robustness against failures in the P2P network, such as packet losses and peer-failure, is increased by either employing odd/even frame MDC or by temporal layering. We show different hybrid MDC schemes and their respective rate distortion curves and redundancy figures, and discuss the impact of packet-loss and peer-failures on these schemes. Given a peer-to-peer network with certain dimensions, loss rates and failure rates and scalability demand we then optimize the quality of the hybrid MDC streaming over a P2P-TV network.

Fbref: Freeband/I-Share/P39v1.0

Where: Picture Coding Symposium, Beijing, China, 24-26 April 2006.

Keywords: hybrid temporal/SNR scalable multiple description coding, peer-to-peer

Correlating Topology and Path Characteristics of Overlay Networks and the Internet

Authors: Alexandru Iosup, Pawel Garbacki, Johan Pouwelse, and Dick Epema

Abstract: Real-world IP applications such as Peer-to-Peer filesharing are now able to benefit from network and location awareness. It is therefore crucial to understand the relation between underlay and overlay networks and to characterize the behavior of real users with regard to the Internet. For this purpose, we have designed and implemented MULTIPROBE, a framework for large-scale P2P file-sharing measurements. Using this framework, we have performed measurements of BitTorrent, which is currently the P2P file sharing network with the largest amount of Internet traffic. We analyze and correlate these measurements to provide new insights into the topology, the connectivity, and the path characteristics of the Internet parts underlying P2P networks, as well as to present unique information on the BitTorrent throughput and connectivity.

Fbref: Freeband/I-Share/P38v1.0

Where: 6th Int'l Workshop on Global and Peer-to-Peer Computing (GP2PC), in conjunction with IEEE/ACM CCGRID, Singapore, May 2006.

Keywords: measurement framework, BitTorrent, Internet topology, overlay networks

Finding a Near Optimal Dependency Channel Model for a LDPC-based Wyner-Ziv Video Compression Scheme

Authors: Ronald P. Westerlaken, Stefan Borchert, Rene Klein Gunnewiek, R. (Inald) L. Lagendijk

Abstract: Research in distributed video coding for low complexity encoding has shown that without knowledge of the correlation between source and side information (i.e. the behavior of the virtual dependency chan- nel), the performance is substantially below that of well known state-of-the-art video coders. In this paper we investigate the modeling of the virtual channel for a pixel-based Wyner-Ziv coding scheme using LDPC codes, and consider both stationary and non-stationary channel models. We have shown in our earlier work that the system significantly benefits from modeling the channel as non-stationary. In this paper we model the PDF of the dependency channel as Laplacian, Gaussian, Generalized Gaussian or two-sided Gamma PDFs. We find for different motion estimation results the PDF parameters for which the distributed video coder has the highest compression ratio. Our results show that the two-sided Gamma and Generalized Gaussian PDFs outperforms the Laplacian and Gaussian approximations. For a certain range of the shape parameter of the Generalized Gaussian model the decoding is less sensitive to the choice of the sigma parameter, when compared to the two-sided Gamma model. We also show that the choice of the PDF parameter(s) and the separation procedure of pixels belonging to occluded and non-occluded regions for which the decoder performs (close to) optimal is critical under different model assumptions.

Fbref: Freeband/I-Share/P37v1.0

Where: Proceedings of the twelfth annual conference of the Advanced School for Computing and Imaging, Lommel, Belgium, June 14-16 2006.

Keywords: low-complexity video encoding, pixel-based Wyner-Ziv coding scheme using LDPC codes, dependency channel models

Dependency Channel Modeling for a LDPC-based Wyner-Ziv Video Compression Scheme

Authors: R.P. Westerlaken, S. Borchert, R. Klein Gunnewiek, R.L. Lagendijk

Abstract: Research in distributed video coding for low complexity encoding has shown that without knowledge of the correlation between source and side information (i.e. the behavior of the dependency channel), the performance is substantially below that of well known state-of-the-art video coders. In a practical system the decoder needs to estimate the statistics in this dependency channel. In this paper we investigate the relation between the compression ratio and the sensitivity of the estimated channel model parameter at the decoder side. We observe that this is a hard task, but not unrealistic. We show that the tolerable parameter range is very dependent on the compression ratio and the (actual) statistics in the dependency channel.

Fbref: Freeband/I-Share/P36v1.0

Where: Proceedings 2006 IEEE International Conference on Image Processing, pp. 277-280, Atlanta, Georgia, USA, October 8-11 2006.

Keywords: low-complexity video encoding, LDPC-based Wyner-Ziv coding scheme, dependency channel model

On Creating Depth Maps from Monoscopic Video using Structure from Motion

Authors: Ping Li, D. Farin, R. Klein Gunnewiek, P. de With

Abstract: The depth-image-based rendering technique is a promising technology for three-dimensional television (3D-TV) systems. For such a system, one of the key components is to generate a high-quality per-pixel depth map, particularly for already existing 2D video sequences. This paper proposes a framework for creating the depth map from uncalibrated video sequences of static scenes using the Structure From Motion (SFM) technique. This paper describes the architecture and the main components of the proposed framework. The initial experimental results show that SFM can be an effective way for creating the depth map, or it can be used to refine the depth map created by other methods, for example, the Depth From Cues (DFC) technique.

Fbref: Freeband/I-Share/P34v1.0

Where: 27th Symposium on Information Theory in the Benelux, vol. 1, Noordwijk, Netherlands, June 2006.

Keywords: 3D-TV, depth map, Structure From Motion, SFM, Depth From Cues, DFC

The Orchard Algorithm: P2P Multicasting without Free-riding

Authors: J.J.D. Mol and D.H.J. Epema and H.J. Sips

Abstract: The main purpose of many current peer-to-peer (P2P) networks is off-line file sharing. However, a potentially very promising use of such networks is to share video streams (e.g., TV programs) in real time. In order to do so, the peers in a P2P network who are interested in the same video stream may employ Application Level Multicasting (ALM). In existing P2P networks, peers may exhibit behaviour which is problematic for ALM: peers tend not to donate any resources (free-riding), and they arrive and depart at a high rate (churn). In this paper we propose the Orchard algorithm for ALM of video streams in P2P systems, which deals with both these problems. By employing a technique called Multiple Description Coding, we split a video stream into several substreams. Orchard creates a dynamic spanning tree for each of these substreams in such a way that in the resulting forest, no peer has to forward more substreams than it receives. Our experiments show that Orchard is capable of providing a good quality of service to every peer, even when peers join and leave the forest at a high rate.

Fbref: Freeband/I-Share/P33v1.0

Where: The Sixth IEEE International Conference on Peer-to-Peer Computing, Cambridge, UK, September 6-8, 2006.

Keywords: peer-to-peer, application-level multicast, multicast, freeriding

2Fast: Collaborative Downloads in P2P Networks

Authors: P. Garbacki and A. Iosup and D.H.J. Epema and M. van Steen

Abstract: P2P systems that rely on the voluntary contribution of bandwidth by the individual peers may suffer from freeriding. To address this problem, mechanisms enforcing fairness in bandwidth sharing have been designed, usually by limiting the download bandwidth to the available upload bandwidth. As in real environments the latter is much smaller than the former, these mechanisms severely affect the download performance of most peers. In this paper we propose a system called 2Fast, which solves this problem while preserving the fairness of bandwidth sharing. In 2Fast, we form groups of peers that collaborate in downloading a file on behalf of a single group member, which can thus use its full download bandwidth. A peer in our system can use its currently idle bandwidth to help other peers in their ongoing downloads, and get in return help during its own downloads. We assess the performance of 2Fast analytically and experimentally, the latter in both real and simulated environments. We find that in realistic bandwidth limit settings, 2Fast improves the download speed by up to a factor of 3:5 in comparison to state-of-the-art P2P download protocols.

Fbref: Freeband/I-Share/P32v1.0

Where: The Sixth IEEE International Conference on Peer-to-Peer Computing, Cambridge, UK, September 6-8, 2006.

Keywords: peer-to-peer, collaborative download, Bittorrent

Tag-Based Navigation for Peer-to-Peer Wikipedia

Authors: Jenneke Fokker, Johan Pouwelse and Wray Buntine

Abstract: We introduce P2P Wikipedia, a prototype of personalized tag-based navigation system for Wikipedia content. It is the first peer-to-peer (P2P) file sharing system able to deal with large files -- like movies, music, and software -- but that is also scalable to HTML content. The combined techniques in our prototype are the automated calculation of tags from HTML content, a personalized P2P file sharing system built on a social network, the use of incentives for user cooperation to optimize system performance, and the design of a graphical user interface with advanced navigational features.

Fbref: Freeband/I-Share/P31v1.0

Where: Collaborative Web Tagging Workshop, WWW 2006 conference, Edinburgh, UK, 22nd May, 2006

Keywords: tag-based navigation, peer-to-peer, wikipedia

Near-future streaming framework for 3D-TV applications

Authors: Goran Petrovic and Peter H. N. de With

Abstract: This paper presents a layered framework for 3D-TV applications, combining multiview and depth-image based approaches in a scalable fashion. To solve the problem of missing data due to disocclusions, we add specific layers for coded occlusion data and the edge-mask information for high-quality 3D rendering of key objects in the scene. We show how the same framework can be extended towards FTV applications by jointly addressing simulcast and multicast transmission. By adopting a distributed delivery architecture, new interesting properties can be realized such as shared processing for the creation and streaming of virtual viewpoints.

Fbref: Freeband/I-Share/P30v1.0

Where: Proceedings IEEE International Conference on Multimedia and Expo (ICME), pp. 1881-1884, July 2006, Toronto, Canada.

Keywords: 3D-TV, 3D video streaming, multiview, depth-image based, multicast transmission

Framework for Layered 3D Video Streaming

Authors: Goran Petrovic and Peter H. N. de With

Abstract: This paper presents a layered framework for 3D-TV applications, combining multiview and depth-image based approaches in a scalable fashion. To solve the problem of missing data due to disocclusions, we add specific layers for coded occlusion data and the edge-mask information for high-quality 3D rendering of key objects in the scene. We show how the same framework can be extended towards FTV applications by jointly addressing simulcast and multicast transmission. By adopting a distributed delivery architecture, new interesting properties can be realized such as shared processing for the creation and streaming of virtual viewpoints. In an extensive system discussion, we conclude that it is possible to adaptively implement our streaming applications using a cross-layered approach. Similarly, the concept of selective reliability optimization can be introduced into our system.

Fbref: Freeband/I-Share/P29v1.0

Where: 27th Symposium on Information Theory in the Benelux, vol. 1 pp. 53-60, June 2006, Noordwijk, The Netherlands.

Keywords: 3D video streaming, multiview, depth-image based, multicast transmission

Unifying User-based and Item-based Collaborative Filtering Approaches

Authors: Jun Wang and Arjen P. de Vries and Marcel J.T. Reinders

Abstract: Memory-based methods for collaborative filtering predict new ratings by averaging (weighted) ratings between, respectively, pairs of similar users or items. In practice, a large number of user or item ratings are not available, due to the sparsity inherent to rating data. Consequently, prediction quality can be poor. This paper re-formulates the memory-based collaborative filtering problem in a generative probabilistic framework, treating individual user-item ratings as predictors of missing ratings. The final rating is estimated by fusing predictions from three sources: predictions based on ratings of the same item by other users, predictions based on different item ratings made by the same user, and, third, ratings predicted based on data from other but similar users rating other but similar items. Existing user-based and item-based approaches correspond to the two simple cases of our framework. The complete model is however more robust to data sparsity, because the different types of ratings are used in concert, while additional ratings from similar users towards similar items are employed as a background model to smooth the predictions. Experiments demonstrate that the proposed methods are indeed more robust against data sparsity and give better recommendations.

Fbref: Freeband/I-Share/P28v1.0

Where: Proc. of the 29th Annual International ACM SIGIR Conference on Research and Development on Information Retrieval, Seattle, WA, USA, August 2006.

Keywords: collaborative filtering, user-based, item-based

On the Value of Random Opinions in Decentralized Recommendation

Authors: E. Ogston, A. Bakker, M. van Steen

Abstract: As the amount of information available to users continues to grow, filtering wanted items from unwanted ones becomes a dominant task. To this end, various collaborative-filtering techniques have been developed in which the ratings of items by other users form the basis for recommending items that could be of interest for a specific person. These techniques are based on the assumption that having ratings from similar users improves the quality of recommendation. For decentralized systems, such as peer-to-peer networks, it is generally impossible to get ratings from all users. For this reason, research has focused on finding the best set of peers for recommending items for a specific person. In this paper, we analyze to what extent the selection of such a set influences the quality of recommendation. Our findings are based on an extensive experimental evaluation of the MovieLens data set applied to recommending movies. We find that, in general, a random selection of peers gives surprisingly good recommendations in comparison to very similar peers that must be discovered using expensive search techniques. Our study suggests that simple decentralized recommendation techniques can do sufficiently well in comparison to these expensive solutions.

Fbref: Freeband/I-Share/P27v1.0

Where: 6th IFIP WG 6.1 International Conference on Distributed Applications and Interoperable Systems (DAIS'06), Bologna, Italy, June 13-16 2006.

Keywords: collaborative filtering, peer-to-peer, recommendation, semantic overlays

Personalization of a peer-to-peer television system

Authors: J. Wang, J. Pouwelse, J. Fokker, and M.J.T. Reinders

Abstract: We introduce Tribler a personalized peer-to-peer (P2P) television system. Personalization allows users to browse programs much more efficiently according to their taste. On the other hand, personalization also enables to build social networks that can improve the performance of current P2P systems considerably by increasing content availability, trust and the realization of proper incentives to exchange content. In this paper, we present a novel scheme, called BuddyCast, that builds such a social network for a user by exchanging user interest profiles using exploitation and exploration principles. Additionally, we show how the interest of a user in TV programs can be derived from the zapping behavior, thereby avoiding the explicit rating of TV programs. Further, we present how the social network of a user can be used to realize a truly distributed recommendation of TV programs. Finally, we demonstrate a novel user interface for the personalized peer-to-peer television system that encompasses a personalized tag-based navigation to browse the available distributed content. The user interface also visualizes the social network of a user, thereby increasing community feeling which increases trust amongst users and within available content and creates incentives of to exchange content within the community.

Fbref: Freeband/I-Share/P26v1.0

Where: 4th European Conference on Interactive Television, Athens, Greece, May 25-26 2006.

Keywords: personalization, peer-to-peer networks, peer-to-peer television

Distributed Collaborative Filtering for Peer-to-Peer File Sharing Systems

Authors: Jun Wang, Johan Pouwelse, Inald Lagendijk, Marcel J. T. Reinders

Abstract: Collaborative filtering requires a centralized rating database. However, within a peer-to-peer network such a centralized database is not readily available. In this paper, we pro- pose a fully distributed collaborative filtering method that is self-organizing and operates in a distributed way. Simi- larity ranks between multimedia files (items) are calculated by log-based user profiles and are stored locally at these items in so-called buddy tables. This intuitively creates a semantic overlay to organize multimedia files. Based on this semantic overlay and the items that a user has downloaded previously (indicating the profile of the user), recommenda- tions can be performed and the recommended items can be easily located. We have tested our distributed collaborative filtering approach and compared it to centralized collabo- rative filtering, showing that it has similar performance. It is therefore a promising technique to facilitate filtering for relevant multimedia data in P2P networks.

Fbref: Freeband/I-Share/P25v1.0

Where: Proceedings of the 21st Annual ACM Symposium on Applied Computing, April 2006.

Keywords: recommendation, personalization, collaborative filtering, peer-to-peer networks

A User-Item Relevance Model for Log-based Collaborative Filtering

Authors: Jun Wang, Arjen P. de Vries, Marcel J.T. Reinders

Abstract: Implicit acquisition of user preferences makes log-based collaborative filtering favorable in practice to accomplish recommendations. In this paper, we follow a formal approach in text retrieval to re-formulate the problem. Based on the classic probability ranking principle, we propose a probabilistic user-item relevance model. Under this formal model, we show that user-based and item-based approaches are only two different factorizations with different independence assumptions. Moreover, we show that smoothing is an important aspect to estimate the parameters of the models due to data sparsity. By adding linear interpolation smoothing, the proposed model gives a probabilistic justification of using TFxIDF-like item ranking in collaborative filtering. Besides giving the insight understanding of the problem of collaborative filtering, we also show experiments in which the proposed method provides a better recommendation performance on a music play-list data set.

Fbref: Freeband/I-Share/P24v1.0

Where: European Conference on Information Retrieval (ECIR 2006), April 2006.

Keywords: collaborative filtering, user-item relevance model

Tribler: A Social-Based Peer-to-Peer System

Authors: J. Pouwelse, P. Garbacki, J. Wang, A. Bakker, J. Yang, A. Iosup, D. Epema, M. Reinders, M. van Steen, H. Sips.

Abstract: Most current P2P file sharing systems treat their users as anonymous, unrelated entities, and completely disregard any social relationships between them. However, social phenomena such as friendship and the existence of communities of users with similar tastes may be well exploited in such systems, to increase their usability and performance. In this paper we present a novel social-based P2P file-sharing paradigm that exploits social phenomena by maintaining social networks and using these in content discovery, content recommendation, and downloading. Based on this paradigm.

Fbref: Freeband/I-Share/P23v1.0

Where: 5th International Workshop on Peer-to-Peer Systems (IPTPS'06), Santa Barbara, CA, USA, Feb. 2006.

Keywords: peer-to-peer, social-based

2005

Towards Stimulating Cooperative Behavior In Peer-To-Peer Networks

Authors: Jenneke E. Fokker, Piet H. Westendorp, Huib de Ridder

Abstract: The merging worlds of the personal computer and television will lead to radically new views on Human Computer Interaction. It is no longer a matter of one user communicating with one computer at a time, but a matter of near-borderless connectivity with other devices and users. This paper describes the relation between trust and characteristics of decentralized systems, both technical and user-oriented. Resulting knowledge is implemented in a prototype of a system called p2p-tv, a future PVR, based on peer-to-peer technology, which enables streaming of live television programs as well as sharing of movies and other video content. P2p-tv tries to tackle

several challenges of systems that have no central authority: freeriding, volatile nature, and a continuously growing, unmonitored amount of information.

Fbref: Freeband/I-Share/P22v1.0

Where: International Conference on Information Systems, Las Vegas, Dec. 2005.

Keywords: cooperative behaviour, peer-to-peer, incentives

Trust in Virtual Communities

Authors: M. R. Czenko, J. M. Doumen, S. Etalle.

Abstract: The objective of our research in the context of the BSIK Freeband project I-SHARE is to provide a sophisticated trust management framework for virtual communities.

Fbref: Freeband/I-Share/P21v1.0

Where: ERCIM News -- Special: Security and Trust Management, vol. 63, pp 29-30, Oct. 2005. ERCIM EEIG, Sophia-Antipolis, France.

Keywords: trust, virtual communities

Two-level Semantic Caches in Super-Peer Networks

Authors: P. Garbacki, D.H.J. Epema, M. van Steen,

Abstract: Some recent measurements studies of file sharing peer-to-peer networks demonstrated the presence of semantics proximity between peers and shared files. This observation may be used for improving performance of the search by introducing of the semantics caches. One type of such cache links peers that are interested in similar files. The query routing mechanism uses this information forwarding the query to peers which are semantically close first. The second type of semantic caches groups similar content rather than similar nodes. In this paper we show how to combine both methods by introducing two-level caching infrastructure based on super-peers. The super-peers in our system cache pointers to files recently requested by the client peers. The client peers, on the other hand, constantly look for the super-peers which are most suitable for them. This mutual dependency results in a self-organizing network topology providing high search performance and quick adjustment to the changes in the environment. We discuss the deisng choices and optimizations of the presented model. We also evaluate our system versus the symmetric network that uses only one level of semantic caches.

Fbref: Freeband/I-Share/P20v1.0

Where: 10th Int'l Workshop on Web Content Caching and Distribution, Sophia-Antipolis, France, Sep. 2005.

Keywords: peer-to-peer, superpeer, semantic caches

Nonmonotonic Trust Management for P2P Applications

Authors: M. R. Czenko and H. M. Tran and J. M. Doumen and S. Etalle and P. H. Hartel and J. I. den Hartog

Abstract: Community decisions about access control in virtual communities are non-monotonic in nature. This means that they cannot be expressed in current, monotonic trust management languages such as the family of Role Based Trust Management languages (RT). To solve this problem we propose RTe, which adds a restricted form of negation to the standard RT language, thus admitting a controlled form of non-monotonicity. The semantics of RT is discussed and presented in terms of the well-founded semantics for Logic Programs. Finally we discuss how chain discovery can be accomplished for RTe.

Fbref: Freeband/I-Share/P19v1.0

Where: 1st Int. Workshop on Security and Trust Management (STM), Milan, Italy, Sep. 2005.

Keywords: trust, trust management, peer-to-peer

The Role of the Virtual Channel in Distributed Source Coding of Video

Authors: R.P. Westerlaken, R. Klein Gunnewiek and R.L. Lagendijk

Abstract: In distributed video source coding side-information at the decoder is generated as a temporal prediction based on previous frames. This creates a virtual dependency channel between the source video at the encoder and the side information at the decoder. In recent years, distributed source coders were introduced with sophisticated error correction codes, like Turbo Codes and LDPC codes. Although these codes performs well on noisy network communication channels, it is far from obvious that these codes can handle the non-stationary noise in the dependency channel as encountered in distributed video coders. In this paper we study the consequences of inaccurate modeling of the dependency channel on Turbo and LDPC coding and show that the performance depends greatly on the choice of the probabilistic model for the dependency channel. The results show that LDPC codes are less sensitive to inaccuracies in the dependency channel models.

Fbref: Freeband/I-Share/P18v1.0

Where: International Conference on Image Processing, Genova, Italy, September 2005.

Keywords: Video compression, virtual channel, distributed source coding

Epidemic-style Management of Semantics Overlays for Content-Based Searching

Authors: S. Voulgaris, M. van Steen

Abstract: A lot of recent research on content-based P2P searching for file-sharing applications has focused on exploiting semantic relations between peers to facilitate searching. To the best of our knowledge, all methods proposed to date suggest reactive ways to seize peers# semantic relations. That is, they rely on the usage of the underlying search mechanism, and infer semantic relations based on the queries placed and the corresponding replies received. In this paper we follow a different approach, proposing a proactive method to build a semantic overlay. Our method is based on an epidemic protocol that clusters peers with similar content. It is worth noting that this peer clustering is done in a completely implicit way, that is, without requiring the user to specify his preferences or to characterize the content of files he shares.

Fbref: Freeband/I-Share/P17v1.0

Where: Proc. Int'l Conf. on Parallel and Distributed Computing (Euro-Par), Lisbon, Portugal, August 2005.

Keywords: peer-to-peer, semantics overlays, epidemic protocols

Self-organizing distributed collaborative filtering

Authors: J. Wang, M.J.T. Reinders, R.L. Lagendijk, and J. Pouwelse

Abstract: We propose a fully decentralized collaborative filtering approach that is self-organizing and operates in a distributed way. The relevances between downloading files (items) are stored locally at these items in so called item-based buddy tables and are updated each time that the items are downloaded. We then propose to use the language model to build recommendations for the different users based on the buddy tables of those items a user has downloaded previously. We have tested and compared our distributed collaborative filtering approach to centralized collaborative filtering and showed that it has similar performance. It is therefore a promising technique to facilitate recommendations in peerto- peer networks.

Fbref: Freeband/I-Share/P16v1.0

Where: ACM SIGIR Conference on Research and Development in Information Retrieval, Bahia, Brazil, August 15-19 2005.

Keywords: collaborative filtering, self-organization

Fair Rate Allocation of Scalable Multiple Description Video for Many Clients

Authors: Jacco Taal and R. (Inald) Lagendijk

Abstract: Peer-to-peer networks (P2P) form a distributed communication infrastructure that is particularly well matched to video streaming using multiple description coding. We form M descriptions using MDC-FEC building on a scalable version of the Dirac video coder. The M descriptions are streamed via M different application layer multicast (ALM) trees embedded in the P2P network. Client nodes (peers in the network) receive a number of descriptions m < M that is dependent on their bandwidth. In this paper we consider the optimization of the received video qualities, taking into account the distribution of the clients' bandwidth. We propose three fairness criteria to define the criterion to be optimized. Numerical results illustrate the effects of the different fairness criteria and client bandwidth distributions on the rates allocated to the compressed video layers and multiple descriptions.

Fbref: Freeband/I-Share/P15v1.0

Where: Proc. Visual Communications and Image Processing, Beijing, July 2005.

Keywords: multiple description coding, scalable coding, erasure codes, peer-to-peer networks, error resilience, path diversity

Distributed Source Coding of Video with Non-Stationary Side-Information

Authors: P.F.A. Meyer, R.P. Westerlaken, R. Klein Gunnewiek, and R.L. Lagendijk

Abstract: In distributed video coding, the complexity of the video encoder is reduced at the cost of a more complex video decoder. Using the principles of Slepian and Wolf, video compression is then carried out using channel coding principles, under the assumption that the video decoder can temporally predict side-information that is correlated with the source video frames. In recent work on distributed video coding the application of turbo codes has been studied. Turbo codes perform well in typical (tele-)communications settings. However, in distributed video coding the dependency channel between source and side-information is inherently non-stationary, for instance due to occluded regions in the video frames. In this paper, we study the modeling of the virtual dependency channel, as well as the consequences of incorrect model assumptions on the turbo decoding process. We observe a strong dependency of the performance of the distributed video decoder on the model of the dependency channel.

Fbref: Freeband/I-Share/P14v1.0

Where: Visual Communications and Image Processing (VCIP), SPIE, Beijing, July 2005.

Keywords: Distributed source coding, Video compression, Channel coding

CYCLON: Inexpensive Membership Management for Unstructured P2P Overlays

Authors: S. Voulgaris, D. Gavidia, M. van Steen

Abstract: Unstructured overlays form an important class of peer-to-peer networks, notably when contentbased searching is at stake. The construction of these overlays, which is essentially a membership management issue, is crucial. Ideally, the resulting overlays should have low diameter and be resilient to massive node failures, which are both characteristic properties of random graphs. In addition, they should be able to deal with a high node churn (i.e., expect high-frequency membership changes). Inexpensive membership management while retaining random-graph properties is therefore important. In this paper, we describe a novel gossip-based membership management protocol that meets these requirements. Our protocol is shown to construct graphs that have low diameter, low clustering, highly symmetric node degrees, and that are highly resilient to massive node failures. Moreover, we show that the protocol is highly reactive to restoring randomness when large numbers of nodes fail.

Fbref: Freeband/I-Share/P13v1.0

Where: Journal of Network and Systems Management, 13(2):197-217, June 2005.

Keywords: Membership management, Peer-to-Peer, Epidemic/Gossiping Protocols, Unstructured Overlays, Random Graphs

Integrity Constraints in Trust Management (Extended Abstract)

Authors: S. Etalle and W. H. Winsborough

Abstract: We introduce the use, monitoring, and enforcement of integrity constraints in trust management-style authorization systems. We consider what portions of the policy state must be monitored to detect violations of integrity constraints. Then we address the fact that not all participants in a trust management system can be trusted to assist in such monitoring, and show how many integrity constraints can be mon- itored in a conservative manner so that trusted participants detect and report if the system enters a policy state from which evolution in unmonitored portions of the policy could lead to a constraint violation.

Fbref: Freeband/I-Share/P12v1.0

Where: Proceedings 10th ACM Symp. on Access Control Models and Technologies (SACMAT), G-J. Ahn (eds.), Stockholm, Sweden. June 2005. ACM Press, New York.

Keywords: trust, trust management, integrity constraints

Distributed collaborative filtering for peer-to-peer file sharing systems

Authors: J. Wang, M.J.T. Reinders, R.L. Lagendijk, and J. Pouwelse

Abstract: Peer-to-peer networks are becoming more and more popular to share information such as, for example, multimedia files. Since this information is stored locally at the different peers, it is necessary to facilitate the search in an intelligent way. Collaborative filtering is such a search technique that enables to incorporate the preferences of a user that can be learned from the download activities of the users. To be effective collaborative filtering requires a large database that captures these activities. Within a peerto- peer network this is, however, not readily available. Here, we propose a collaborative filtering approach that is self-organizing and operates in a distributed way. Information about the similarity between multimedia files (items) is stored locally at these items in so called item-based buddy tables. We propose to use the language model (popular within information retrieval) to build recommendations for the different users based on the buddy tables of those items a user has downloaded previously (indicating the preference of the user). We have tested and compared our distributed collaborative filtering approach to centralized collaborative filtering and showed that it has similar performance. It is therefore a promising technique to facilitate the search for information in peer-to-peer networks.

Fbref: Freeband/I-Share/P11v1.0

Where: Proceedings Eleventh annual conference of the Advanced School for Computing and Imaging, June 2005.

Keywords: collaborative filtering, peer-to-peer

Turbo-code based Wyner-Ziv video compression

Authors: R. P. Westerlaken, R. Klein Gunnewiek, R. L. Lagendijk

Abstract: In distributed video coding, the complexity of the video encoder is reduced at the cost of a more complex video decoder. In recent work on distributed video coding the application of turbo codes has been studied. Turbo codes perform well in typical (tele-)communications settings. However, in distributed video coding the dependency channel between source and side-information is inherently non-stationary, for instance due to occluded regions in the video frames. In this paper, we study the modeling of the virtual dependency channel, as well as the consequences of incorrect model assumptions on the turbo decoding process. We observe a strong dependency of the performance of the distributed video decoder on the model of the dependency channel.

Fbref: Freeband/I-Share/P10v1.0

Where: IEEE/WIC Symposium on Information Theory in the Benelux, Brussels, May 2005.

Keywords: video compression, turbo code, Wyner-Ziv

Scalable multiple description video for fair streaming to many clients

Authors: J. R. Taal, R. L. Lagendijk

Abstract:

Fbref: Freeband/I-Share/P9v1.0

Where: IEEE/WIC Symposium on Information Theory in the Benelux, Brussels, May 2005.

Keywords: video compression, multiple description coding, scalable coding, erasure codes, peer-to-peer networks, error resilience, path diversity

The BitTorrent P2P File-Sharing System: Measurements and Analysis

Authors: J.A. Pouwelse, P. Garbacki, D.H.J. Epema, and H.J. Sips

Abstract: Of the many P2P file-sharing prototypes in existence, BitTorrent is one of the few that has managed to attract millions of users. BitTorrent relies on other (global) components for file search, employs a moderator system to ensure the integrity of file data, and uses a bartering technique for downloading in order to prevent users from freeriding. In this paper we present a measurement study of BitTorrent in which we focus on four issues, viz. availability, integrity, flashcrowd handling, and download performance. The purpose of this paper is to aid in the understanding of a real P2P system that apparently has the right mechanisms to attract a large user community, to provide measurement data that may be useful in modeling P2P systems, and to identify design issues in such systems.

Fbref: Freeband/I-Share/P8v1.0

Where: The 4th Int'l Workshop on Peer-to-Peer Systems (IPTPS'05), Ithaca, NY, February 2005.

Keywords: peer-to-peer, BitTorrent, measurements

Wi-Fi walkman: a wireless handhold that shares and recommends music on peer-to-peer networks

Authors: Jun Wang, Marcel J.T. Reinders, Johan Pouwelse, Reginald L. Lagendijk

Abstract: The Wi-Fi walkman is a mobile multimedia application that we developed to investigate the technological and usability aspects of human-computer interaction with personalized, intelligent and context-aware wearable devices in peer-to-peer wireless environments such as the future home, office, or university campuses. It is a small handheld device with a wireless link that contains music content. Users carry their own walkman around and listen to music. All this music content is distributed in the peer-to-peer network and is shared using ad-hoc networking. The walkman naturally interacts with the users and users' interest with each other in a peer-to-peer environment. Without annoying interactions, it can learn the users' music interest/taste and consequently provide personalized music recommendation according to the current situated context and user's interest.

Fbref: Freeband/I-Share/P7v1.0

Where: In the conference on Embedded Processors for Multimedia and Communications II, part of the IS&T/SPIE Symposium on Electronic Imaging 2005, Jan 2005.

Keywords: peer-to-peer, recommendation, personalization, user's interest

P2P-based PVR Recommendation using Friends, Taste Buddies and Superpeers

Authors: Johan Pouwelse, Michiel van Slobbe, Jun Wang, Marcel J.T. Reinders, Henk Sips

Abstract: In this paper we present a novel distributed recommendation method based on exchanging similar playlists among taste buddies, which takes into account the limited availability of peers, lack of trust in P2P networks, and dynamic identities of peers, etc. Our preliminary experiment shows that only exchanging a small portion of similar playlists from taste buddies could lead to an efficient way to calculate recommendations within a context of P2P networks.

Fbref: Freeband/I-Share/P6v1.0

Where: Proceedings of Beyond Personalizaion 2005, the Workshop on the Next Sage of Recommender Systems Research (IUI2005), San Diego, California, January 9-12 2005.

Keywords: collaborative filtering, recommendation, peer-to-peer, superpeers, taste buddies

Automatic IEEE 802.11 Rate Control for Streaming Applications

Authors: I. Haratcherev and J.R. Taal and K. Langendoen and R.L. Lagendijk and H. Sips

Abstract: Streaming multimedia content in real-time over a wireless link is a challenging task because of the rapid uctuations in link conditions that can occur due to movement, interference, and so on. The popular IEEE 802.11 standard includes low-level tuning parameters like the transmission rate. Standard device drivers for today's wireless products are based on gathering statistics, and consequently, adapt rather slowly to changes in conditions. To meet the strict latency requirements of streaming applications, we designed and implemented an advanced hybrid control algorithm that uses signal-strength (SNR) information to achieve fast responses. Since SNR readings are quite noisy we do not use that information to directly control the rate setting, but rather as a safeguard limiting the range of feasible settings to choose from. We report on real-time experiments involving two laptops equipped with IEEE 802.11a wireless interface cards. The results show that using SNR information greatly enhances responsiveness in comparison to statistics-based rate controllers. Finally, we will present the results of an experiment with realtime video streaming to a moving laptop in an overce-like environment. Our hybrid control algorithm ectively prevented many packets losses, thereby achieving a much higher video quality than the statistics based algorithm.

Fbref: Freeband/I-Share/P5v1.0

Where: Wireless Communications and Mobile Computing, special issue on Radio Link and Transport Protocol Engineering for Future-Generation Wireless Mobile Data Networks, 2005.

Keywords: rate control, MAC layer, SNR, link adaptation, video streaming

Fast 802.11 link adaptation for real-time video streaming by cross-layer signaling

Authors: Ivaylo Haratcherev and Jacco R. Taal and Koen Langendoen and R.(Inald) Lagendijk and Henk Sips

Abstract: The quality of real-time video streaming over wireless links is significantly reduced due to packet losses and delays caused by rapid changes of the link conditions. We resolve this problem by two solutions. In the first place, we have developed a responsive MAC adaptation method using SNR and packet loss statistics. The second solution depends on the first one, it allows the MAC to communicate information about changes of link conditions to the video codec. Together, these solutions will prevent packet losses and skipped frames, both of which have an adverse effect on the visual quality of the decoded video. In this paper we present the results of an streaming video experiment using an 802.11a link between a fixed an a mobile station. We show that with the cross-layer signaling between the MAC-layer and the video coder, an increase of 4dB visual quality is achievable.

Fbref: Freeband/I-Share/P4v1.0

Where: Proc. International Symposium on Circuits and Systems, Tokyo, Japan, 2005.

Keywords: video streaming, rate control, MAC layer, SNR, link adaptation, cross-layer interaction

2004

Scalable Multiple Description Coding for Video Distribution in P2P Networks

Authors: J.R. Taal, J.A. Pouwelse, R.L. Lagendijk

Abstract: In this paper we present and evaluate a method for video distribution through a peer-to-peer (P2P) network using Multiple Description Coding in a multicast tree. Our method solves the problem of serving many clients with heterogeneous bandwidths. Every node forwards descriptions to other nodes. Nodes that have sufficient bandwidth are then able to receive more descriptions, and thereby to increase the quality. We use a combination of a layered video codec and erasure coding to generate multiple descriptions. Given different client-bandwidth distribution functions, we optimize a fairness criterion such as the (average) quality for all clients. Since we optimize the average quality for all clients as a group, the performance for individual clients may be very different. We discuss the reduction in quality for clients that have bandwidths other than average as opposed to a single description stream. Finally, we discuss the efficiency, in terms of bit rate and redundancy, for all clients as a group, and individually.

Fbref: Freeband/I-Share/P3v1.0

Where: Picture Coding Symposium, San Francisco, December 15-17, 2004.

Keywords: video compression, multiple description coding, scalable coding, peer-to-peer networks

Music2Share---Copyright Compliant Music Sharing in P2P Systems

Authors: T. Kalker, D.H.J. Epema, P.H. Hartel, R.L. Lagendijk and M. van Steen

Abstract: Peer-to-peer (P2P) networks are generally considered to be free havens for pirated content, in particular with respect to music. We describe a solution for the problem of copyright infringement in P2P networks for music sharing. In particular, we propose a P2P protocol that integrates the functions of identification, tracking, and sharing of music with those of licensing, monitoring, and payment. This highly decentralized music-aware P2P protocol will allow access to large amounts of music of guaranteed quality; it merges in a natural way the policing functions for copyright protection and an efficient music-management infrastructure for the benefit of the user.

Fbref: Freeband/I-Share/P2v1.0

Where: Proceedings of the IEEE, vol. 92, no. 6, pp. 961-970, 2004

Keywords: content-aware networks, digital rights management (DRM), fingerprinting, multimedia, music sharing, peer-to-peer (P2P), search protocols, watermarking

Real-time Video Delivery using Peer-to-Peer Bartering Networks and Multiple Description Coding

Authors: J.A. Pouwelse, J.R. Taal, R.L. Lagendijk, D.H.J. Epema, and H.J. Sips

Abstract: Broadband Internet access using ADSL or cable modems provides sufficient bandwidth for real-time video streaming. If television channels could be distributed on the Internet, each channel would get a world wide audience. However, television distribution from a single server does not scale and IP-level multicasting is complex and costly. We propose a solution based on application-level multicasting using a P2P network, called P2P-TV. Each peer receives a video stream and must also forward this stream to others. This paper presents an architecture for streaming video. Our P2P-TV proposal aims to solve three problems that are currently not addressed in other P2P streaming proposals, namely 1) maximizing the usage of all available peer bandwidth, 2) taking current network conditions into account (network awareness), and 3) the Freeriding problem. Multiple Description Coding is an integral part of our solution. By splitting the video stream into smaller streams we can utilize all the bandwidth of a peer. Multiple streams allow more efficient adaptation of the multicast tree to current network conditions. Bittorrent-like bartering of content is also enabled by using multiple streams.

Fbref: Freeband/I-Share/P1v1.0

Where: Proc. IEEE Conf. on Systems, Man, and Cybernetics (SMC), The Hague, October 11-13, 2004, pp. 4599-4605.

Keywords: video streaming, multiple description coding, scalable coding, peer-to-peer networks

Reports

TriblerShare: A Scalable P2P-Based Web 2.0 Platform

Authors: F. van der Werf

Abstract: Over the last few years, there has been a rise on the Internet of so-called social web services. In contrast with traditional web services where users only consume information, social web services enable users to interact with each other. This new approach to web services is often referred to as Web 2.0. Socialized web services have become very popular as shown by examples like YouTube, Flickr, andWikipedia. However, these sites operate in a centralized way, and the drawback of their popularity is the increased operating costs. At the same time, Peer-to-Peer (P2P) technology has gained much popularity in the area of content distribution because of its lack of central components, which causes P2P systems to scale well. Therefore, P2P technology may be a solution for the poor scalability of current Web 2.0 services. This thesis describes the research we have conducted in providingWeb 2.0 services with scalable P2P technology. We have extended Tribler, an existing P2P client, such that it enables each user to easily share his videos, photos, etc., with other users. Furthermore, we have developed a flexible system that provides access to the large collections of content items available from current popularWeb 2.0 web sites. This system is easily extensible, and adding support for a new web site requires only to define structure of the site. Using these interfaces, we also decentralize current Web 2.0 web sites by distributing retrieved items in the Tribler network.

Fbref: Freeband/I-Share/R16v1.0

Where: Master's thesis Delft University of Technology, Feb 2008.

Keywords: web 2.0, peer-to-peer

Performance Analysis of Chainsaw-Based Live P2P Video Streaming

Authors: P. Duijkers

Abstract: Due to the growing popularity of viewing media over the Internet, content servers are suffering from more and more stress every day. This problem is traditionally solved by enhancing the server infrastructure at the content provider, which is effective but also costly. A more cost effective solution would be to use P2P technology to distribute the media stream in real-time. For this purpose, the Chainsaw algorithm has been proposed, which performs very well in simulations. However, Chainsaw has not been implemented in a real video player yet. We have built our own version of Chainsaw called Kettingzaag, and we have added some improvements and features which make it more resillient to errors, such as multiple description coding. Kettingzaag is put to the test in our own video player called Lumberjack, on the DAS-3 supercomputer in Delft. Our experiments show that the Kettingzaag algorithm performs well for network sizes up to a hundred nodes, and is likely to perform just as well for larger network sizes.

Fbref: Freeband/I-Share/R15v1.0

Where: Master's thesis Delft University of Technology, Dec 2008.

Keywords: peer-to-peer, video-on-demand, chainsaw

Improving P2P Applications by Breaking the Architecture Symmetry

Authors: P. Garbacki

Abstract: If bandwidth consumption were the determining factor of the impact of an Internet application, P2P systems would be at the top of the ranking. The continued growth of the popularity of P2P applications has stimulated the involvement of the research community in improving the designs of current P2P systems and in building new types of such systems. Applications such as live video streaming, Video-on-Demand (VoD), and Content Distribution Networks (CDNs) have extended the scope of P2P technology, which originally targeted file sharing and content searching. Compared to their predecessors, these new applications require more efficient and reliable protocols. For instance, video distribution systems impose lower bounds on the minimum sustainable bandwidth needed to offer a continuous video playback experience to their users, while CDNs cannot tolerate high latencies. The emerging design challenges have defined the direction in which the research field of P2P systems has evolved. P2P technology has indeed come a long way from the initial designs relying heavily on centralized components to fully distributed architectures. Somewhere along the way, the practical aspects of designing P2P systems optimized with respect to the heterogeneity of the Internet resources have been overshadowed by the appealing symmetry of architectures composed of homogenous components. The negligence of the resource, configuration, and social heterogeneity of the Internet results in suboptimal performance of symmetric P2P designs. Despite its practical importance, to date only a handful of P2P applications have considered the possibility of leveraging the heterogeneity of their deployment environments in their designs. Among these applications, an important class is represented by asymmetric designs which assign additional roles in the system to high-capacity peers. In this thesis we argue for the potential of asymmetric architectures of P2P systems, and we investigate their applicability in various application settings.

Fbref: Freeband/I-Share/R14v1.0

Where: PhD Thesis, Delft University of Technology, December 2008, Delft, The Netherlands

Keywords: peer-to-peer, architecture symmetry

LP with Flexible Grouping and Aggregates Using Modes

Authors: M.R. Czenko and S. Etalle

Abstract: We propose a new grouping operator for logic programs based on the group_by operator of SQL. The novelty of our proposal lies in the use of modes, which allows us to relax some rather unpractical constraints on variable occurrences while retaining a straightforward semantics. Moreover, modes allow us to prove properties regarding groundness of computed answer substitutions and termination. The resulting class of programs enjoys a simple and intuitive semantics.

Fbref: Freeband/I-Share/R13v1.0

Where: Technical Report Centre for Telematics and Information Technology, University of Twente, June 2008.

Keywords: logic programs, SQL, modes

Trust Management in P2P systems using Standard TuLiP

Authors: M. R. Czenko and J. M. Doumen and S. Etalle

Abstract: In this paper we introduce Standard TuLiP - a new logic based Trust Management system. In Standard TuLiP, security decisions are based on security credentials, which can be issued by different entities and stored at different locations. Standard TuLiP directly supports the distributed credential storage by providing a sound and complete Lookup and Inference AlgoRithm (LIAR). In this paper we focus on (a) the language of Standard TuLiP and (b) on the practical considerations which arise when deploying the system. These include credential encoding, system architecture, system components and their functionality, and also the usability issues.

Fbref: Freeband/I-Share/R12v1.0

Where: Technical Report Centre for Telematics and Information Technology, University of Twente, January 2008

Keywords:

2007

Core TuLiP

Authors: M. R. Czenko and S. Etalle

Abstract: We propose CoreTuLiP - the core of a trust management language based on Logic Programming. CoreTuLiP is based on a subset of moded logic programming, but enjoys the features of TM languages such as RT; in particular clauses are issued by different authorities and stored in a distributed manner. We present a lookup and inference algorithm which we prove to be correct and complete w.r.t. the declarative semantics. CoreTuLiP enjoys uniform syntax and the well-established semantics and is expressive enough to model scenarios which are hard to deal with in RT.

Fbref: Freeband/I-Share/R11v1.0

Where: Technical Report Centre for Telematics and Information Technology, University of Twente, March 2007.

Keywords:

An Introduction to the Role Based Trust Management Framework RT

Authors: M. R. Czenko and S. Etalle and D. Li and W. H. Winsborough

Abstract: Trust Management (TM) is a novel flexible approach to access control in distributed systems, where the access control decisions are based on the policy statements, called credentials, made by different principals and stored in a distributed manner. In this chapter we present an introduction to TM focusing on the role-based trust-management framework RT. In particular, we focus on RT0, the simplest representative of the RT family, and we describe in detail its syntax and semantics. We also present the solutions to the problem of credential discovery in distributed environments.

Fbref: Freeband/I-Share/R10v1.0

Where: Technical Report Centre for Telematics and Information Technology, University of Twente, June 2007

Keywords:

Creating and Maintaining Relationships in Social Peer-to-Peer Networks

Authors: S. Koolen

Abstract: Peer-to-Peer (P2P) systems are a good alternative to conventional client-server systems for distribution of content. Many different approaches exist towards the design of P2P networks, which should take into account scalability, efficiency, availability and integrity. The approach discussed in this thesis creates a network based on social relations between users, called a social P2P overlay network. In order to create a social P2P network, users must be able to create and maintain connections to friends. Two main problems in creating a social P2P network are identified and discussed in this thesis. The first is the social network discovery problem. We have designed and implemented a protocol to spread and search user identities through the social network using an epidemic protocol and superpeers. The use of epidemic protocols in social networks is a scalable and efficient way of spreading the identities of users. The second problem is the peer IP address discovery problem. We have performed an analysis of the dynamics of IP addresses of peers in a BitTorrent community as well as in the Tribler network. From this analysis we conclude that IP dynamics are relatively low. Therefore, changes in IP addresses can be propagated through the network and the chance is high that IP changes can be discovered through the social network.

Fbref: Freeband/I-Share/R9v1.0

Where: Master's thesis Delft University of Technology, 12 January 2007.

Keywords: social networks, peer-to-peer, IP-address changes

2006

Tribler Campus: An Integrated Peer-to-peer Platform for File Distribution in Course Management Systems

Authors: M. Meulpolder

Abstract: Course Management Systems (CMSs) are widely used in educational institutes to manage course information and to distribute educational content. All major implementations of such systems (e.g., Blackboard, Moodle) are based on a client-server architecture. Because of this, the performance and scalability of these systems are limited, especially regarding the distribution of multimedia and digital lectures to large numbers of people. TriblerCampus aims to overcome this problem, by integrating the Tribler peer-to-peer software with the CMS Moodle. The user interacts in the usual way with the CMS, while in the background large files are distributed in peer-to-peer fashion. Caching and replication mechanisms are introduced to further improve the performance and scalability. In this presentation, the design and implementation of TriblerCampus are presented, as well as an extensive performance analysis based on mathematical analysis, simulation and experiments.

Fbref: Freeband/I-Share/R8v1.0

Where: Master's thesis Delft University of Technology, 31 October 2006.

Keywords: course management systems, peer-to-peer, Blackboard, Tribler

Secure Decentralized Swarm Discovery in Tribler

Authors: J. Roozenburg

Abstract: The decentralized architecture of peer-to-peer (P2P) networks solves many of the limitations of conventional client-server networks. This decentralization, however, creates the need in P2P file sharing networks to find peers who are downloading the same file, a problem which is referred to as swarm discovery. In the BitTorrent file sharing network, swarm discovery is solved using a central server (a tracker), which is unreliable and unscalable. We have designed a decentralized swarm discovery protocol, called LITTLE BIRD. LITTLE BIRD is an epidemic protocol that exchanges swarm information between peers that are currently or were recently members of a swarm. A quantitative measure of the contribution of each peer is calculated to make the protocol efficient and secure against peers that pollute the system with malicious information. Furthermore, we have conducted detailed measurements of the BitTorrent community 'Filelist.org', in order to study download swarm behavior and optimize the design of our protocol. We have implemented the LITTLE BIRD protocol as an addition to the Tribler P2P network. For the evaluation of LITTLE BIRD, we have created an experimental environment called CROWDED, which enables us to conduct large-scale trace-based emulations of swarms on the DAS-2 supercomputer. Evaluation results show that our protocol scales with the swarm size, uses moderate bandwidth overhead, and is resilient against denial-of-service and pollution attacks. Therefore, LITTLE BIRD enables secure, scalable and reliable swarm discovery.

Fbref: Freeband/I-Share/R7v1.0

Where: Master's thesis Delft University of Technology, 10 November 2006.

Keywords: Bittorrent, decentralized tracker, peer-to-peer

2005

Lighthouse: A Distributed Recommendations System for Television Programs

Authors: M. van Slobbe

Abstract: With computer hardware becoming less expensive all the time and the arrival of dozens of television channels, the market for a Personal Video Recorder (PVR) is booming. Such a PVR lets its user record tens of hours of television in an easy manner. A so-called recommender system helps the user in filtering out relevant information from this long list of content. Until now, the most effective filtering solution, Collaborative Filtering, uses a central server to store the data of each user in the system and calculate recommendations. The Lighthouse system offers the effectivity of Collaborative Filtering without the need for a central server. This system has been developed on the basis of two assumptions. First, having similar playlists improves the quality of the recommendations. Second, finding these similar playlists is most effective when each node retrieves its most similar playlists by default and looks for these where it finds its most similar playlists (similarity is commutative). As we will show, both assumptions are validated by experiments. The Lighthouse system makes use of these features to offer recommendations of a good quality to users, with next to no cost per node. A custom peer-to-peer network lets nodes communicate with each other and eliminates the need for a central server. Additionally, as compared to a central server solution, changes in user playlists are propagated much faster. As a result, a new program can be recommended much earlier.

Fbref: Freeband/I-Share/R6v1.0

Where: Master's thesis Delft University of Technology, 25 August 2005.

Keywords: collaborative filtering, distributed recommendation, peer-to-peer

Integrity Constraints in Trust Management

Authors: S. Etalle and W. H. Winsborough

Abstract: We introduce the use, monitoring, and enforcement of integrity constraints in trust managementstyle authorization systems. We consider what portions of the policy state must be monitored to detect violations of integrity constraints. Then we address the fact that not all participants in a trust management system can be trusted to assist in such monitoring, and show how many integrity constraints can be monitored in a conservative manner so that trusted participants detect and report if the system enters a policy state from which evolution in unmonitored portions of the policy could lead to a constraint violation.

Fbref: Freeband/I-Share/R5v1.0

Where: Centre for Telematics and Information Technology, Univ. of Twente, The Netherlands, Technical report, nr. to appear, Apr. 2005.

Keywords: trust, trust management, integrity constraints

The Interface Selection Layer: Improving QoS using Interface Pair Selection

Authors: C.F. van Antwerpen

Abstract: The Internet is getting larger and larger. Every day more devices get connected to it. But the same goes for the local networks at people's home. There are however two major differences between the infrastructure of the Internet and of the home network. In a home network devices are added but not always replaced and it consists of mainly low-cost unmanaged devices. The result is a chaotic network with congestion problems. The devices in the home network have multiple interfaces and offer all kinds of services, so the number of connections and the number of paths between devices (peer-to-peer connections between the interfaces of devices) are increasing. Current devices choose a path at random when they want to communicate with another device. To avoid congestion we want to choose which path the device must use. But to make a good choice we need information about the current state of each of the paths to compare the paths. We present a solution to offer this path selection functionality to a device by collecting information about the different paths and using this information to choose the best path.

Fbref: Freeband/I-Share/R4v1.0

Where: Master's Thesis, Eindhoven University of Technology, 2005.

Keywords: quality of service, interface pair selection

2004

Slepian Wolf Turbo Coding of Video with Non-Stationary Side-information

Authors: P. Meyer

Abstract: In the early seventies, Slepian and Wolf first introduced source coding with side-information at the decoder. This coding principle allows for a low-complexity encoder, provided that the decoder has access to a sideinformation signal that is dependent on the source signal. In video source coding, we are able to generate this side-information by using a predictive video model. In the last decades, this possibility has been further explored, revealing that turbo codes are a serious candidate for this purpose. Turbo codes have been studied and used as an error correcting code for quite a long time now. In the light of recent research in Wyner-Ziv coding for video compression, the question has risen whether turbo code based compression systems will be capable to handle the inherent non-stationary noise introduced by the predictive video model generating the side-information at the decoder. State of the art motion estimation algorithms are very capable of error-free prediction of the larger part of the frame based only on previous frames. However, some situations, such as occlusions, will always remain a problem in frame prediction, causing location-specific noise. In this paper, we investigate the coding of non-stationary noise using a turbo code based Slepian-Wolf system. From the experiments described here, we can conclude that turbo code based systems have a limited capability of dealing with location-specific, badly described noise. We will also demonstrate that even relatively primitive information about the location and the underlying symbol probabilities will assist in the decoding process.

Fbref: Freeband/I-Share/R3v1.0

Where: Master's Thesis, Delft University of Technology, October 12, 2004

Keywords: video compression, turbo coding, Slepian Wolf

An Introduction to the BitTorrent Peer-to-Peer File Sharing System

Authors: J.A. Pouwelse, P. Garbacki, D.H.J. Epema, and H.J. Sips

Abstract: Over the last few years, quite a few peer-to-peer (P2P) protocols for sharing files (e.g. containing music or movies) have been devised. However, despite the increasing attention from both the research community and hundreds of thousands of users, the behavior of such systems under a real workload of actual users is poorly understood. One of the most promising current P2P file-sharing systems that is quickly gaining popularity, is the BitTorrent/Suprnova system. This paper is an attempt to understand the operation of P2P file sharing by means of detailed measurements of the use and operation of BitTorrent to assess its quality with respect to such aspects as download speed and availability. In addition, we propose improvements to the existing architecture.

Fbref: Freeband/I-Share/R2v1.0

Where: Hand-out at the 19th IEEE Annual Computer Communications Workshop, Oct 2004, Bonita Springs.

Keywords: peer-to-peer, BitTorrent

Simulating Cooperation in Ad-hoc Networks

Authors: Taco Dijkstra

Abstract: Wireless ad-hoc networks, which are becoming very popular, have no central administration or predefined network structure. An example of this type of network is the Context Aware Communication, Terminal and USer (CACTUS) project, in which a small group of people (e.g., a group of tourists) form an ad-hoc network and can communicate with each other using intelligent Devices acting as Electronic Agents (i-DEAs). An ad-hoc network has as a drawback that nodes have to send, besides their own traffic, relay packets for others. The reason for this is that their communication range is limited due to their restricted send power. This extra foreign traffic costs extra energy, and energy is very limited for battery powered devices. Therefore nodes try to save their energy as much as possible. One way of doing this, is by refusing to forward packets for others. This is obviously compromising the correct functioning of the ad-hoc network, and in the worst case parts of the network gets partitioned. We have therefore done simulations in the OPNET network simulator to test the functioning of the mathematical Generous TIT-FOR-TAT (GTFT) model, which stimulates nodes to cooperate. Nodes utilizing the GTFT algorithm have to contribute to the network, otherwise they cannot send their own packets, i.e., every node is stimulated to forward packets for others. In this report we present the results of these simulations using GTFT and show that some additional work is needed before the full potential of algorithms like GTFT can be utilized.

Fbref: Freeband/I-Share/R1v1.0

Where: Master's Thesis, Delft University of Technology, 20 December 2004.

Keywords: ad-hoc networks, cooperation

Deliverables

The distribution of I-Share deliverables is limited to Freeband, please use DocuShare or contact A.Bakker@few.vu.nl to get a copy.

WP1

I-Share Deliverable 1.1: Trust Management in Virtual Communities

Authors: Marcin Czenko, Jeroen Doumen, Pieter Hartel

Abstract: Trust management is an important component of security systems. It helps us to make decisions about who should be allowed to access our resources, and which of them. We present a general overview of the most important approaches to trust management. We also address some not yet covered aspects of trust related to virtual communities and sharing in P2P networks.

Fbref: Freeband/I-Share/D1.1v1.0

Where: I-Share Deliverable.

Keywords: trust, trust management, virtual communities

I-Share Deliverable 1.2: Technical Report on the Human Side of Cooperating in Decentralized Networks

Authors: Jenneke E. Fokker, Huib de Ridder

Abstract: This is a report on the human side of the willingness to cooperate, and on our knowledge of decision-making strategies in unmanaged networks. It is concerned with the technical and psychological determinants of sharing in virtual communities with a focus on inducing the willingness to cooperate. Unmanaged / decentralized networks are challenging, because in general, they have to deal with heterogeneity, freeriding, a dynamic / volatile nature, a constantly expanding amount of information and increasing complexity. But the individual limitations of nodes in unmanaged networks can be overcome if nodes are willing to share their resources. But, as will become clear, this is not as obvious as it may seem. Human behavior needs to be taken into account. Humans are not always rational, and their actions possibly contradict with what is expected from a technology point of view. As human decision making in this environment is largely unpredictable, knowledge will have to be gained on the willingness to cooperate. Sharing in virtual communities is concerned with both technical and psychological determinants. For a user, the technology only makes sense if it is deemed trustworthy, if he understands the meaning and options the techniques offer him, if these options are presented in a transparent way, and, even more important, if it gives him high profits and low costs. All of this requires a clear understanding of the technological possibilities and constraints, but also of human decision making strategies. Research-through-design will be the approach, because it is envisaged that the resulting human centered interface aspects complement already existing technology-oriented systems and even make them more acceptable.

Fbref: Freeband/I-Share/D1.2v1.0

Where: I-Share Deliverable.

Keywords: cooperation, peer-to-peer, incentives

I-Share Deliverable 1.3: Simulating Cooperation in Ad-hoc Networks.

Authors: D.H.J. Epema and T. Dijkstra

Abstract: The basic research subject of the I-SHARE project is the sharing of resources of different kinds in networked computer systems. In multihop wireless ad-hoc networks, two nodes that want to communicate may not be in each other#s communication range, and they may therefore need intermediate nodes for relaying traffic between them. In this setting, the resources to be shared are bandwidth and energy, which are scarce resources in wireless systems. In this report we present a simulation study of the so-called Generous TIT-FOR-TAT (GTFT) model for node co-operation in multihop wireless ad-hoc networks. In GTFT, nodes keep track of their contribution to the network and of their benefit from the network, and a node is only willing to share, that is, to accept relay requests, when the ratio of its contribution and benefit is within certain limits. This report constitutes the MSc thesis of T. Dijkstra at the PDS group of Delft University of Technology, under the supervision of D.H.J. Epema.

Fbref: Freeband/I-Share/D1.3v1.0

Where: I-Share Deliverable.

Keywords: ad-hoc networks, cooperation

I-Share Deliverable 1.4: Basic Protocol for Virtual Communities

Authors: Arno Bakker, Elth Ogston, Maarten van Steen

Abstract: In the I-Share project we seek for means to share content that is distributed across potentially large groups of users. The approach that we explore in this report is to group users in virtual communities, where each community consists of users having a similar taste. The basic idea is that the searching for and sharing of content can be simplified if we can restrict ourselves to relatively small communities. Therefore, our present aim is to find algorithms for automatically forming virtual communities. First, we elaborate on the basic problem of searching and grouping users. Next, we describe in detail an algorithm that will allow us to cluster data in a decentralized manner, and describe experiments that illustrate the quality of our algorithm. Finally, as a next step towards building virtual communities using our algorithm, we analyze a data set expressing the television-viewing behavior of a group of 3049 users.

Fbref: Freeband/I-Share/D1.4v1.0

Where: I-Share Deliverable.

Keywords: peer-to-peer, clustering, virtual communities

I-Share Deliverable 1.5: Service Discovery, Access and Cooperation in Virtual Communities

Authors: Shudong Chen, Johan J. Lukkien, Igor Radovanovi

Abstract: Service Oriented Architecture (SOA) is emerging as an enabling technology for sharing distributed heterogeneous resources that may be under the control of different owners in a network such as Internet. However, if the number of the available services over a network is huge, publishing the available services, discovering the desired services while maintaining a transparent access control is not an easy task. It includes research challenges such as how a service provider protects its ownership, privacy and how a service user finds a desired service securely. In this report, we present a SOA with a virtual community approach to address these challenges. The approach includes definition and formation of a virtual community, mechanisms of service discovery, access and cooperation inside a virtual community. We also introduce the Ambient Open Service Architecture (AMOSA) software platform which is the test bed of our approach. Using AMOSA, heterogeneous services which are using different types of technologies, for instance, UPnP and Web Services can be rewrapped into AMOSA services and then be used within a single framework. AMOSA services can be discovered using uniform mechanism and communicate with each other without protocol adaptation at the service side. Moreover, services can be organized into virtual communities to achieve secure service discovery and cooperation.

Fbref: Freeband/I-Share/D1.5v1.0

Where: I-Share Deliverable.

Keywords: SOA, Ambient Open Service Architecture (AMOSA), virtual communities

I-Share Deliverable 1.6: Initial Design and Testing of the Tribler User Interface

Authors: J. Fokker, H. de Ridder, P. Westendorp, M. de Groot.

Abstract: Tribler is social peer-to-peer (P2P) software for sharing multimedia, and in particular video content. A first test version of Tribler was released on the 17th of March 2006. In one week's time the client was downloaded 15.000 times from the Tribler website. To get fast feedback from the users a survey was put on the Tribler.org website. This report gives an account of the results from the user survey.

Fbref: Freeband/I-Share/D1.6v1.0

Where: I-Share Deliverable.

Keywords: user-interface design, survey

I-Share Deliverable 1.7: Taxonomy of Cooperation Inducing Interface Features

Authors: J. Fokker, H. de Ridder, P. Westendorp

Abstract: This report presents a taxonomy of cooperation inducing interface features. It is based on an inventory of proof-of-concept interfaces from market leading applications whose successes rely on cooperation of a large amount of users. This inventory is clustered and then structured along key phenomena from sociology and psychology. The report finishes with design guidelines for interfaces that will induce cooperation among the users.

Fbref: Freeband/I-Share/D1.7v1.0

Where: I-Share Deliverable.

Keywords: user-interface design, cooperation

I-Share Deliverable 1.8: The Orchard Algorithm: P2P Multicasting without Free-riding

Authors: J.J.D. Mol, D.H.J. Epema, H.J. Sips

Abstract: The main purpose of many current peer-to-peer (P2P) networks is off-line file sharing. However, a potentially very promising use of such networks is to share video streams (e.g., TV programs) in real time. In order to do so, the peers in a P2P network who are interested in the same video stream may employ Application Level Multicasting (ALM). In existing P2P networks, peers may exhibit behaviour which is problematic for ALM: peers tend not to donate any resources (free-riding), and they arrive and depart at a high rate (churn). In this paper we propose the Orchard algorithm for ALM of video streams in P2P systems, which deals with both these problems. By employing a technique called Multiple Description Coding, we split a video stream into several substreams. Orchard creates a dynamic spanning tree for each of these substreams in such a way that in the resulting forest, no peer has to forward more substreams than it receives. Our experiments show that Orchard is capable of providing a good quality of service to every peer, even when peers join and leave the forest at a high rate.

Fbref: Freeband/I-Share/D1.8v1.0

Where: I-Share Deliverable.

Keywords: peer-to-peer, multicast, freeriding

I-Share Deliverable 1.9: 2 Fast: Collaborative Downloads in P2P Networks

Authors: P. Garbacki, A. Iosup, D.H.J. Epema, M. van Steen

Abstract: P2P systems that rely on the voluntary contribution of bandwidth by the individual peers may suffer from freeriding. To address this problem, mechanisms enforcing fairness in bandwidth sharing have been designed, usually by limiting the download bandwidth to the available upload bandwidth. As in real environments the latter is much smaller than the former, these mechanisms severely affect the download performance of most peers. In this paper we propose a system called 2Fast, which solves this problem while preserving the fairness of bandwidth sharing. In 2Fast, we form groups of peers that collaborate in downloading a file on behalf of a single group member, which can thus use its full download bandwidth. A peer in our system can use its currently idle bandwidth to help other peers in their ongoing downloads, and get in return help during its own downloads. We assess the performance of 2Fast analytically and experimentally, the latter in both real and simulated environments. We find that in realistic bandwidth limit settings, 2Fast improves the download speed by up to a factor of 3-5 in comparison to state-of-the-art P2P download protocols.

Fbref: Freeband/I-Share/D1.9v1.0

Where: I-Share Deliverable.

Keywords: peer-to-peer, collaborative downloads

I-Share Deliverable 1.10: Core TuLiP

Authors: M. Czenko and S. Etalle

Abstract: Virtual communities are groups of individuals with a shared interest, relationship or fantasy. The majority of current virtual communities is interested in sharing audio/video content using P2P systems. Taking into account the distributed nature of virtual communities, special mechanisms for access control must be provided to ensure secure operations at both intra- and inter-community levels. Trust Management (TM) is an approach to access control in decentralised distributed systems where access control decisions are based on policy statements issued by multiple principals, and stored in a distributed manner. We are convinced that each community member should be able to decide its own strategy for controlling access to her resources rather than depend on a hard-coded policy provided by the TM system designer. To achieve this, one needs a TM language which is expressive enough to handle diverse user scenarios, and has a well-defined semantics, so that access control decisions can be made without risk of ambiguity. Because of the distributed nature of Virtual Communities, the language should also incorporate mechanisms that successfully deal with distributed storage of policy statements involved in access control decisions. In this deliverable we describe CoreTuLiP - the core of a trust management language based on Logic Programming. CoreTuLiP is based on a subset of moded logic programming, but enjoys the features of TM languages. In particular policy statements can be issued by different authorities and stored in a distributed manner. We present a lookup and inference algorithm which we prove to be correct and complete w.r.t. the declarative semantics. CoreTuLiP enjoys uniform syntax and well-established semantics and is expressive enough to model scenarios which are hard to deal with in other trust management languages.

Fbref: Freeband/I-Share/D1.10v1.0

Where: I-Share Deliverable.

Keywords: distributed trust management, virtual communities, trust management language

I-Share Deliverable 1.11: Decentralized Recommendation Algortihms

Authors: E. Ogston, A. Bakker, M. van Steen

Abstract: As the amount of information available to users continues to grow, filtering wanted items from unwanted ones becomes a dominant task. To this end, various collaborative-filtering techniques have been developed in which the ratings of items by other users form the basis for recommending items that could be of interest for a specific person. These techniques are based on the assumption that having ratings from similar users improves the quality of recommendation. For decentralized systems, such as peer-to-peer networks, it is generally impossible to get ratings from all users. For this reason, research has focused on finding the best set of peers for recommending items for a specific person. In this report, we analyze to what extent the selection of such a set influences the quality of recommendation. Our findings are based on an extensive experimental evaluation of the MovieLens 100.000 and 1.000.000 data sets applied to recommending movies. We find that, in general, a random selection of peers gives surprisingly good recommendations in comparison to very similar peers that must be discovered using expensive search techniques. Our study suggests that simple decentralized recommendation techniques can do sufficiently well in comparison to these expensive solutions.

Fbref: Freeband/I-Share/D1.11v1.0

Where: I-Share Deliverable.

Keywords: collaborative filtering, peer-to-peer, recommendation, semantic overlays

I-Share Deliverable 1.12: On Securing Decentralized Algorithms for Peer Discovery

Authors: A. Bakker, M. van Steen

Abstract: In this deliverable we look at decentralized algorithms for peer discovery and how they can be secured against malicious peers trying to interfere in various ways. We focus on securing the discovery of peers with certain extrafunctional attributes, in particular, uptime, bandwidth, latency, and trust with changing values. We analyse the problems of discovery on extrafunctional attributes in a secure manner and indicate how they can be solved for certain applications. A number of problems, however, remain unsolved and leave current decentralized discovery algorithms extremely vulnerable to attacks.

Fbref: Freeband/I-Share/D1.12v1.0

Where: I-Share Deliverable.

Keywords: peer-to-peer, peer discovery, security, gossip protocols

I-Share Deliverable 1.13: Video-on-Demand in Peer-to-Peer Systems

Authors: J.J.D. Mol, J.A. Pouwelse, M. Meulpolder, D.H.J. Epema, H.J. Sips

Abstract: Centralised solutions for Video-on-Demand (VoD) services, which stream pre-recorded video content to multiple clients who start watching at the moments of their own choosing, are not scalable because of the high bandwidth requirements of the central video servers. Peer-to-peer (P2P) techniques which let the clients distribute the video content among themselves, can be used to alleviate this problem. However, such techniques may introduce the problem of free-riding, with some peers in the P2P network not forwarding the video content to others if there is no incentive to do so. When the P2P network contains too many free-riders, an increasing number of the well-behaving peers may not achieve high enough download speeds to maintain an acceptable service. In this paper we propose Give-to-Get, a P2P VoD algorithm which discourages freeriding by letting peers favour uploading to other peers who have proven to be good uploaders. As a consequence, free-riders are only tolerated as long as there is spare capacity in the system. Our simulations show that even if 20% of the peers are free-riders, Give-to-Get continues to provide good performance to the well-behaving peers. In particular, they show that Give-to-Get performs very well for short videos, which dominate the current VoD traffic on the Internet.

Fbref: Freeband/I-Share/D1.13v1.0

Where: I-Share Deliverable.

Keywords: peer-to-peer, video-on-demand, give-to-get

I-Share Deliverable 1.14: Security Aspects of the P2P-TV Client: A Secure Peer Sampling Service

Authors: A. Bakker, M. van Steen

Abstract: In this deliverable we present and evaluate a design for a secure Peer Sampling Service. A Peer Sampling Service (PSS) provides a node in an overlay network with a random sample of the other nodes in the overlay. Currently, an insecure PSS is used in our P2P-TV client as part of the Buddycast algorithm for discovering peers with similar taste in content. Replacing this insecure service with a secure variant is a first step into making our client secure.

Fbref: Freeband/I-Share/D1.14v1.0

Where: I-Share Deliverable.

Keywords: peer sampling service, security

I-Share Deliverable 1.15: Trust Management in P2P systems using Standard TuLiP - An extension of the TuLiP trust management language

Authors: M. Czenko, J. Doumen, S. Etalle

Abstract: In this deliverable we present the system architecture of standard TuLiP - a logic based Trust Management system. Standard TuLiP is a practical realisation of Core TuLiP - its theoretical foundations - which has been described in our previous deliverable.

Fbref: Freeband/I-Share/D1.15v1.0

Where: I-Share Deliverable.

Keywords: trust management, tulip

I-Share Deliverable 1.16: VICSDA System Design and Prototype

Authors: S. Chen, J. Lukkien, R. Verhoeven, R. Bosman, M. Tjiong

Abstract: This document presents the system design of the virtual community architecture which is called VICSDA (VIrtual Community based Service Discovery and Access). We construct this virtual community overlay by extending the current AMOSA software platform. The current AMOSA platform can provide the ability to build services with virtual community functionality and to compose new applications within virtual community boundaries. A prototype is implemented to test the design.

Fbref: Freeband/I-Share/D1.16v1.0

Where: I-Share Deliverable.

Keywords: virtual communities, service discovery, AMOSA platform

I-Share Deliverable 1.17: Pilot Remote User Experience Test of Tribler, using TUMCAT Technology

Authors: Jenneke E. Fokker, Huib de Ridder, Piet Westendorp, Arnold Vermeeren

Abstract: Peer-to-peer television (P2P-TV) systems like Tribler depend on the inducement of massive cooperation among users. In Tribler, knowledge from (social) psychology on altruistic behavior is used for developing cooperation inducing mechanisms. Aiming to verify the effectiveness of these incentives, this paper presents the first remote user experience test of the current version of Tribler. The test focused on four usage-related issues: downloading, seeding, moderation, and social reach. It was found that the current users are mainly interested in downloading. Users hardly seeded and performed few actions in relation to social reach or moderation.

Fbref: Freeband/I-Share/D1.17v1.0

Where: I-Share Deliverable.

Keywords: pilot, user trial, peer-to-peer, incentives

I-Share Deliverable 1.18: Evaluation of the Evolving User Interface over Different Versions of Tribler

Authors: J. Fokker, H. de Ridder, P. Westendorp, A. Vermeeren

Abstract: Since the first Tribler release in March 2006 several user tests and design iterations have been performed over time on different versions. This deliverable briefly describes the versions, user-tests, suggested adjustments to the design, and redesigns iteratively. The aim of this deliverable is to communicate the development of the user interface over time and to present different methods of user testing. Next to traditional laboratory usability tests, remote in-situ longitudinal studies have been performed as well as Internet surveys.

Fbref: Freeband/I-Share/D1.18v1.0

Where: I-Share Deliverable.

Keywords: user interface evaluation, Tribler

I-Share Deliverable 1.19: IPTV and IMS for Collaborative Content Consumption

Authors: X. Zhou, A. Tokmakoff, A. Argyriou, D. Goergen, D. Lowet

Abstract: The purpose of this document is to introduce emerging IPTV and IMS technologies and describe how I-Share solutions can exploit them to enable collaborative content consumption of user generated content. It serves to provide a high level view on the functionalities they provide, and also to indicate the relations that exist between these functionalities when applied towards an illustrative use case.

Fbref: Freeband/I-Share/D1.19v1.0

Where: I-Share Deliverable.

Keywords: IPTV, IMS, Web4CE

I-Share Deliverable 1.20: Acceptability of Delayed Reciprocity in Peer-to-Peer TV Systems

Authors: J. Fokker, H. de Ridder, P. Westendorp

Abstract: Using Peer-to-Peer (P2P) technology for distributing video files to many viewers simultaneously can only be successful if users cooperate voluntarily and massively. The current BitTorrent protocol enforces instantaneous bandwidth exchange within the context of one video file. To better exploit available resources for P2P-TV systems, such as the Tribler (www.tribler.org) software, we explore ways to induce user cooperation flexible over time and resources. The research is based on the social exchange theory and is done in two steps. First, the impact of social distance expressed in the degrees of separation (DoS) on the trust in reciprocity is investigated. Second, the DoS are combined with the kind of exchangeable resources typical for P2P systems (i.e. injections and bandwidth) to find the influence of these variables on the accepted delay in reciprocity. The discussion will focus on the relation between trust in reciprocity and the accepted delay in reciprocity in P2P systems in the context of video exchange.

Fbref: Freeband/I-Share/D1.20v1.0

Where: I-Share Deliverable.

Keywords: user cooperation, social exchange theory, delayed reciprocity

I-Share Deliverable 1.21: The Design and Deployment of a BitTorrent Live Video Streaming Solution

Authors: J.J.D. Mol, A. Bakker, J.A. Pouwelse, D.H.J. Epema and H.J. Sips

Abstract: The BitTorrent protocol is by far themost popular protocol for offline peer-topeer video distribution on the Internet. BitTorrent has previously been extended to support the streaming of recorded video, that is, Video-on-Demand (VoD). In this paper, we take this support for video streaming a step further and present extensions to BitTorrent for supporting live video streaming that we have implemented in our BitTorrent called Tribler. We have tested our implementation in a public trial on the Internet, which lasted 9 days and during which 4555 unique peers participated from around the globe. Most of the peers obtained acceptable performance, with for instance a very low prebuffering time before playback starts, indicating the feasibility of our approach. The median prebuffering time we measured was 3.6 seconds, which is 3-10 times shorter than the prebuffering time measured in other deployed systems. We will analyze the performance data collected during the trial in detail, and we will discuss the lessons learned from the trial.

Fbref: Freeband/I-Share/D1.21v1.0

Where: I-Share Deliverable.

Keywords: bittorrent, live streaming, trial

I-Share Deliverable 1.22: Further Extensions of the TuLiP Trust Management Language

Authors: M. Czenko, J. Doumen and S. Etalle

Abstract: In this deliverable we describe a further extensions of the TuLiP trust management language (described in I-Share deliverables D1.10 and D1.15). We divide the work into two parts. The first part shows the full version of our trust management system TuLiP. Here we further extend the TuLiP trust management language with unlimited arguments, user-defined constraints and redundant storage. We also formalise the notions introduced informally in I-Share deliverable D1.15 (like multiple storage options, constraints, and XML content). In the second part we describe how to do grouping and aggregations in logic programming in the way preserving important to trust management properties of termination and groundness of the computer answer substitutions. Grouping and aggregation is needed if one wants to bridge the credential based and the reputation based trust management in one comprehensive framework. This is outside the scope of this deliverable to show how to integrate grouping and aggregations into TuLiP system, but we give strong theoretical foundation for this work to be carried out successfully.

Fbref: Freeband/I-Share/D1.22v1.0

Where: I-Share Deliverable.

Keywords: trust management, termination, groundness.

I-Share Deliverable 1.23: Security in Higher-Level Epidemic

Protocols: A Secure Tagging Service

Authors: A. Bakker and M. van Steen

Abstract: In D1.14 we investigated attacks on the basic mechanisms of epidemic protocols. In this deliverable we look at attacks on the higher-level functions of epidemic protocols, such as attempts at poisoning the data being distributed. We do so in the context of a tagging service that allows authorized parties to retroactively add tags to content published in an open distribution network such as Tribler. We present a scalable design for this service and show how it can be secured against malicious attacks by building on our work from D1.14.

Fbref: Freeband/I-Share/D1.23v1.0

Where: I-Share Deliverable.

Keywords: secure tagging, bittorrent, puppetcast, randcast

I-Share Deliverable 1.24: A Context-aware Resource Management Middleware for Service Oriented Applications Based on Cross-Layer Monitoring

Authors: Shudong Chen, Johan Lukkien, Richard Verhoeven

Abstract: Distributed services hosted by electronic devices can be composed into applications using external service orchestration. Since the collaboration involves multiple parties and happens over the Internet, without access control and proper quality of service (QoS) management this type of application is unacceptable. This paper presents VICSDA, a context-aware resource management middleware for service oriented applications, which aims to secure service discovery and access, and to handle the inherent dynamics of services and the network. Devices and services are organized in virtual communities. All activities happen within a virtual community. Only authenticated users are capable to access services and resources. VICSDA accepts application-oriented QoS, gathers statistics of required services and their dynamic resource utilization through a cross-layer monitoring architecture, and updates the service coordination decisions according the real time states of the environment of a running application. For these, two novel services are designed. One is the resource manager which anticipates the performance of both required services and the network and be aware of the environment changes. Another is a device manager which runs on each device and has the fully control of services and their underlying resources. A 3D video streaming application is chosen to prove the feasibility of VICSDA. The system adapts the video encoding parameters and the delivery protocol to the observed capability of the end device and the bandwidth of the channel. Concrete results showed that based on measurable and manageable services, VICSDA is context-aware and can optimize the overall performance of service oriented applications.

Fbref: Freeband/I-Share/D1.24v1.0

Where: I-Share Deliverable.

Keywords: context-aware resource management, virtual community, cross-layer monitoring, service orientation

I-Share Deliverable 1.25: Converged IPTV Session Management Requirements and Design

Authors: D. G\"orgen, A. Tokmakoff, X. Zhou, A. Argyriou

Abstract: In this deliverable, we present a generic model and the requirements/high-level design for a session management approach which is an enabler for converged IPTV applications that span several physical devices and locations. Our session model adopts a hierarchical approach, which separates local and global views of the session. The local view of a session enables encapsulation of in-home network/service topologies while the global view allows different content types to be managed between participants inside a single coherent session. Our generic model allows the integration of different multimedia sessions, Web applications and services in converged IPTV environments.

Fbref: Freeband/I-Share/D1.25v1.0

Where: I-Share Deliverable.

Keywords: IPTV, session management

I-Share Deliverable 1.26: Design of a Mechanism for Fair Home Network Resource Sharing Between 2D and 3D Streams

Authors: M. Krause, M. van Hartskamp, R. Verhoeven, J. Lukkien

Abstract: This deliverable investigates TCP fairness and stability of several TCP flavors in relation to the queuing policies used by forwarding devices in the network. The scope is a low-latency network like a home network where many TCP flows are competing for the available bandwidth. We investigate the feasability of achieving a stable and fair bandwidth share in case of congestion. We investigate TCP behavior for up to three competing flows by experiments. Furthermore, we investigate by simulation the combination of five TCP flavors and six queuing policies to find the best performing combination of queuing policy and TCP flavor. Our results show that TCP behavior may be highly irregular and unfair, especially when the number of flows increases, but that combining Deficit Round Robin queuing and TCP New Reno shows stable and predictable behavior.

Fbref: Freeband/I-Share/D1.26v1.0

Where: I-Share Deliverable.

Keywords: bandwidth sharing, TCP flavors, low latency network

I-Share Deliverable 1.27: A Prototype for Fair Sharing of Home Network Resources Across 2D and 3D Video Streams

Authors: M. Krause, M. van Hartskamp

Abstract: This deliverable reports on the 2008 activities for building a prototype for the fair sharing of home network resources across 2D and 3D video streams.

Fbref: Freeband/I-Share/D1.27v1.0

Where: I-Share Deliverable.

Keywords: prototype, fair sharing, home network

WP2

I-Share Deliverable 2.1: Video Compression in Resource Constrained Environments

Authors: P.H.N. de With, R.P. Westerlaken, P. van der Stok, G. Petrovic, J.R. Taal, P. Li, R.L. Lagendijk, R. Klein Gunnewiek , D. Jarnikov, Q. Chen, S. Borchert.

Abstract: The deliverable summarizes the I-Share research on resource-constrained video compression. This research involves three I-Share partners, namely TU Eindhoven, Philips Research and TU-Delft.

Fbref: Freeband/I-Share/D2.1v1.0

Where: I-Share Deliverable.

Keywords: video compression, resource-constrained environments

I-Share Deliverable 2.2: First Implementation of Video Streaming Software

Authors: G. Petrovic, P. de With

Abstract: The purpose of this deliverable is to document the implementation of our first 3D video streaming setup. See also paper Freeband/I-Share/P30v1.0.

Fbref: Freeband/I-Share/D2.2v1.0

Where: I-Share Deliverable.

Keywords: 3D video streaming

I-Share Deliverable 2.3: Implementation of wireless video streaming software

Authors: Marek Burza, Jeffrey Kang, Peter van der Stok

Abstract: This paper describes a method for robust streaming of combined MPEG audio/video content (MPEG-2, H.264) over in-home wireless networks. We make use of currently used content distribution formats and network protocols. The transmitted bit-rate is constantly adapted to the available network bandwidth, such that audio and video artifacts caused by packet loss are avoided. Bit-rate adaptation is achieved by using a packet scheduling technique called I-Frame Delay (IFD), which performs prioritybased frame dropping upon insufficient bandwidth. We show an implementation using RTP and an implementation using TCP. Measurements on a real-life demonstrator set-up demonstrate the effectiveness of our approach.

Fbref: Freeband/I-Share/D2.3v1.0

Where: I-Share Deliverable.

Keywords: adaptive video streaming, wireless networks, MPEG, H.264, I-Frame Delay

I-Share Deliverable 2.4: Experiment on multiple video streaming over in home networks

Authors: M. Krause, P.D.V. van der Stok

Abstract: This report compares the results of different protocols with regards to concurrently streamed videos over a shared wireless access point. In chapter 2, we give some background information on the used protocols (TCP, UDP, RTP and HTTP) as well as the used algorithm (IFD) and some general information on MPEG-2 video streams. In chapter 3, we describe the setup we used to run the experiments on, present the used programs and the hardware. Chapter 4 will present the results that are achieved in this environment. The technical note ends with conclusions and ideas for future work in Chapter 5.

Fbref: Freeband/I-Share/D2.4v1.0

Where: I-Share Deliverable.

Keywords: video streaming, wireless networks, home networks

I-Share Deliverable 2.5: Demonstration of a Stereoscopic and Multiple-Perspective 3D-TV Video Streaming System

Authors: Goran Petrovic, Peter H.N. de With

Abstract: This deliverable presents and accompanies our implementation of an experimental system for 3D-video streaming over IP networks. The system includes software modules to demonstrate two key aspects of 3D video

streaming: (1) stereoscopic video streaming, (2) monoscopic streaming with remote multiple-perspective rendering. The current version of the system implements these two 3D-video modalities as separate applications. The integration is ongoing and planned for the next release version.

Fbref: Freeband/I-Share/D2.5v1.0

Where: I-Share Deliverable.

Keywords: prototype, 3D-video streaming, stereoscopic video streaming, monoscopic streaming with remote multiple-perspective rendering

I-Share Deliverable 2.6: Subjective Quality Analysis of bit rate exchange between temporal and SNR scalability in the MPEG4 SVC extension

Authors: M.A.J. Barzilay, J.R. Taal and R.L. Lagendijk

Abstract: It is well known that a compression trade-off exists between the spatial and temporal video quality. Various temporal scalability techniques have been considered for lowering the encoded frame rate such that the freed bit rate can be used to increase the PSNR quality of the remaining frames. Temporal scalability in the SVC extension of the MPEG4/AVC codec [1] is realized by the hierarchical B-frame structure or the open loop MCTF approach. We investigate the usefulness of the hierarchical B-frame structure as a tool for scaling the bit rate. We use the patented Video Quality Metric (VQM) to measure the subjective quality, in this way explicitly taking into account temporal artifacts due to frame rate reduction. Our results indicate that there is little to no quality gain by exchanging frame rate for increased spatial quality at a given constant bit rate.

Fbref: Freeband/I-Share/D2.6v1.0

Where: I-Share Deliverable.

Keywords: Temporal scalability, hierarchical B-frames, subjective quality, Video Quality Metric (VQM)

I-Share Deliverable 2.7: Demonstration of Mesh-Based Layered 3D Streaming for Stereoscopic Video

Authors: G. Petrovic, P. de With

Abstract: The purpose of this deliverable is to document the implementation of our 3D video streaming demonstration system. This deliverable is complementary to "D 2.5: Demonstration of a Stereoscopic and Multiple-Perspective 3D-TV Video Streaming System", as they both describe the same experimental system. The implementation focus of the D 2.5 is on the multiple-perspective component of the demonstration system, while D.2.7 covers the stereoscopic component of the same system. The complete system incorporating both aspects was demonstrated at Nirict Kick-off meeting 2007 and ICT Delta 2007.

Fbref: Freeband/I-Share/D2.7v1.0

Where: I-Share Deliverable.

Keywords: 3D video demonstrator

I-Share Deliverable 2.8: Enhancing Channel Decoding in Distributed Video Coding

Authors: R.P. Westerlaken, S. Borchert, R. Klein Gunnewiek, R.L. Lagendijk

Abstract: Many distributed video coders are implemented using sophisticated error correction codes that use soft information ( conditional probabilities) as a priori knowledge. This a priori information models the dependency behavior between the input data and side-information. In this deliverable we analyze both a symbol and bit plane based approach using LDPC codes. We show that a bit plane-based encoder has the same performance as a symbol-based coder, if an appropriate dependency model is chosen. We argue that due to a significant complexity reduction a bit plane-based coder is preferable over a symbol based approach.

Fbref: Freeband/I-Share/D2.8v1.0

Where: I-Share Deliverable.

Keywords: error correction codes, LDPC codes, bit plane-based coder

I-Share Deliverable 2.9: Bandwidth Detection and Congestion Control Algoritms

Authors: M. Krause

Abstract: Bandwidth in wireless networks is typically neither large nor predictable enough for multiple Audio/Video (A/V) transmissions. In fact, depending on which network type and video transmission format is used, in most of the cases, only one stream can be used at a time. With evolving technology, bandwidth is growing, to support multiple video streams, but the fundamental technical problems will exist further on. Those problems are coming by using the licensefree ISN-Bands and the physical features of the used waves. Obstacles, reflections, distance, and concurrent technologies using the same band are the course of reduced and fluctuating bandwidth. One of the methods for reducing the actual bandwidth of a video stream is controlled frame dropping. Controlled frame dropping enables predictable video transmissions, but can only be used to a certain extend. Knowledge about perception of frame rate and frame dropping is therefore essential to drop frames without negatively influencing the perceived video quality. In this paper, we define an objective quality metric for frame dropping methods. This quality metric can be used to determine when frame dropping is no longer sufficient and other methods have to be used as well. We make an inventory for the possible impacts of frame dropping from two perspectives, the human visual system and the video coding scheme. This results in a list of quality characteristics specifically for frame dropping. From this list, we conclude that the three most important characteristics for the influence of frame dropping on the perceived video quality are the following: (1) There is a strong correlation between a quality impact, like noticing a frame drop, and the annoyance of the viewers. (2) Viewers can accept and adapt better to multiple short gaps than to one long gap in a video stream. (3) Viewers forget their annoyance after a quality impact like a noticed gap within a short period of time. This is known as recency phenomenon in the human working memory. We construct an objective quality metric based on these characteristics.

Fbref: Freeband/I-Share/D2.9v1.0

Where: I-Share Deliverable.

Keywords: bandwidth detection, congestion control algorithms, quality metrics

I-Share Deliverable 2.10: Creating Depth Maps from 2D Video Sequences

Authors: Ping Li, Rene Klein Gunnewiek, Goran Petrovic, Peter H. N. de With

Abstract: We have proposed and implemented a system for 3D scene modeling from image sequences. A sparse scene model is first reconstructed using the factorization-based structure-from-motion algorithm. The sparse model is then converted to a dense one using Delauney triangulation. The contribution of this work is: 1) we propose and implement a complete framework for constructing 3D models from 2D images; 2) we improve robustness of the projective reconstruction; 3) we contribute a feature-point matching algorithm that is able to reliably track a large number of feature points along a long sequence of images.

Fbref: Freeband/I-Share/D2.10v1.0

Where: I-Share Deliverable.

Keywords: 3D video, depth maps, 2D video

I-Share Deliverable 2.11: Software Implementation DSC Decoder That Merges Bit Plane Decoder and Motion Estimation Process

Authors: S. Borchert, R.P. Westerlaken, R. Klein Gunnewiek, R.L. Lagendijk

Abstract: In the software implementation there are two methods to combine bit plane decoding and motion estimation. In therst the motion estimation helps the bit plane decoding by providing a reliability mask. In the second the motion estimation can be repeated based on decoded bit planes (i.e. partial reference information).

Fbref: Freeband/I-Share/D2.11v1.0

Where: I-Share Deliverable.

Keywords: distributed video coding

I-Share Deliverable 2.12: Experimental Setup Robust Market Prototype B2B Video Streaming System

Authors: Qingxiang Xu, P. de With

Abstract: The focus of this report is video streaming. For interactive video streaming, in order to maintain a high level of user interactivity, delay must remain relatively small (200 ms is the estimated perceptual tolerance of the user). Due to its real-time nature, the video data must be played out continuously. If the data does not arrive in time, the playout process will pause, which is annoying to human eyes. Furthermore, a short delay means that the lost packets often cannot be retransmitted, leading to a displayed picture of significantly lower quality than in the loss-free case. Therefore, video streaming is a distributed application with stringent bandwidth, delay and loss requirements. However, the current best-effort Internet does not offer any Quality of Service (QoS). This means the current Internet does not provide guarantees on bandwidth, jitter and packet loss rates. Thus, the design of video streaming systems over the Internet poses many challenges. In the current project, the approaches to mitigate the effect of packet loss are examined. To combat the problem of packet loss, error control is an effective technique to recover the lost or erroneously received data and reduce the degradation of video quality.

Fbref: Freeband/I-Share/D2.12v1.0

Where: I-Share Deliverable.

Keywords: robust B2B video streaming demonstrator

I-Share Deliverable 2.14: Side Information and Correlation Channel in DVC.

Authors: R.P. Westerlaken, S. Borchert, R. Klein Gunnewiek, R.L. Lagendijk

Abstract: Distributed video coders heavenly rely on the dependency structure between the original frame and the predicted side information. A higher quality input results in a smaller encoding rate. In earlier papers we have shown that the dependency structure is highly non-stationary. Knowledge about this non-stationary behavior should be incorporated into the decoding process. In this paper we focus on both the construction of the side information and the decoding process with non-stationary data. With regard to the side information we have shown that extrapolation can give a performance gain of up to more than 2dB compared to the widely used interpolation scheme with a GOP-size of 2. Furthermore by dealing with the non-stationary dependency in the decoding process performance gains of more than 1dB up to 2dB dependent on the type of motion and classification can be expected

Fbref: Freeband/I-Share/D2.14v1.0

Where: I-Share Deliverable.

Keywords: distributed video coding, non-stationary dependency structure

I-Share Deliverable 2.17: Incorporating Meshes in 3D Video Steaming

Authors: G. Petrovic, P. de With

Abstract: This deliverable was originally intended to be about extending the 3D video streaming framework to incorporating meshes. A mesh-based video representation allows for higher video rendering quality as well as it enables a hierarchical set up in encoder and/or decoder. This implies that additional information of the scene should be transmitted as well. During the development of the project and its research, it became gradually clear that there are alternatives for 3D rendering which are competitive in performance and have a lower complexity. The development of those rendering algorithms is covered in this report, where reference is being made to published results of alternative algorithms. See also Freeband/I-Share/P108v1.0.

Fbref: Freeband/I-Share/D2.17v1.0

Where: I-Share Deliverable.

Keywords: 3D rendering

WP3

I-Share Deliverable 3.1: Basic Architecture and Demonstrator Plan

Authors: Delft University of Technology, Vrije Universiteit Amsterdam, University of Twente, Eindhoven University of Technology, Philips Research

Abstract: This deliverable describes the motivation, research questions, and basic architecture of three planned I-SHARE demonstrators that will be developed around sharing resources. The architecture will be used as a reference model for the project, and will be updated regularly. The demonstrator proposal is based on discussion with other (FREEBAND) projects, and takes into account the integrated demonstrators that will be developed in collaboration with these other projects. This deliverable also describes the current status of plans and approaches for the demonstrators.

Fbref: Freeband/I-Share/D3.1v1.0

Where: I-Share Deliverable.

Keywords: peer-to-peer, resource sharing

I-Share Deliverable 3.2: I-Share Experimentation and Demonstration Plans

Authors: D.H.J. Epema and J.A. Pouwelse

Abstract: I-SHARE is a project that has research in sharing technology for multimedia content in computer systems as its main goal. As a research vehicle, we have defined P2P-TV, a system for sharing live and recorded video from 10,000+ TV channels and web cams in a P2P fashion. Research issues include how to do recommendations, how to cluster users with similar tastes into virtual communities, how to do P2P-like multicasting of live video, and how to design the user interface. In this report, we give an update of our research ideas, and we present the current status of our ideas for experiments and testbeds.

Fbref: Freeband/I-Share/D3.2v1.0

Where: I-Share Deliverable.

Keywords: peer-to-peer, peer-to-peer television, demonstrator plans

I-Share Deliverable 3.3: Experimental I-Share System: The First Version of the P2P-TV Client

Authors: A. Bakker, J. Yang, Y. Yuan, J. Pouwelse

Abstract: This document accompanies the release of the first version of the Tribler peer-to-peer TV client. This version was released to the public on March 17, 2006 and carries Tribler version number 3.3.4.

Fbref: Freeband/I-Share/D3.3v1.0

Where: I-Share Deliverable.

Keywords: peer-to-peer, television, bittorrent

I-Share Deliverable 3.104: Complete Architectural Design of an I-Share System

Authors: A. Bakker, J. Doumen, P. Garbacki, A. Iosup, J.A. Pouwelse, J. Wang, J. Yang

Abstract: This deliverable describes the current design of the Tribler BitTorrent client that is being developed as part of the I-Share project. It provides detailed specifications for each of the client's new features to enable others to create compatible implementations. It also describes the list of possible new features that will be designed and implemented in subsequent versions. This deliverable will be updated yearly to yield a complete design of an I-Share system at the end of the project.

Fbref: Freeband/I-Share/D3.104v1.0

Where: I-Share Deliverable.

Keywords: peer-to-peer, bittorrent

I-Share Deliverable 3.4: Demonstration of distributed video compression, includes components for (external) integrated demonstrators

Authors: S. Borchert, R.P. Westerlaken

Abstract: This document accompanies our software demonstrator for distributed video compression

Fbref: Freeband/I-Share/D3.4v1.0

Where: I-Share Deliverable.

Keywords: distributed video compression, Wyner-Ziv video coding

I-Share Deliverable 3.5: Second version of the P2P-TV client

Authors: A. Bakker, J. Yang, Y. Yuan

Abstract: This document accompanies the release of the second version of the Tribler peer-to-peer TV client. This version was released to the public on August 29, 2006 and carries Tribler version number 3.5.0.

Fbref: Freeband/I-Share/D3.5v1.0

Where: I-Share Deliverable.

Keywords: peer-to-peer, bittorrent

I-Share Deliverable 3.6: P2P Multicast Demonstrator

Authors: J.J.D. Mol, Q. Chen, D.H.J. Epema, J.R. Taal

Abstract: Tribler Streaming is software for streaming a live video feed across the Internet to up to millions of users. It uses peer-to-peer technology to distribute the video stream amongst the viewers. With this technology, a server can host a video channel for a flat fee, regardless of the number of viewers. This is accomplished by distributing the burden of sending the video stream to all viewers. This document accompanies version 1.0.7 of Tribler Streaming, released on December 22, 2006.

Fbref: Freeband/I-Share/D3.6v1.0

Where: I-Share Deliverable.

Keywords: live streaming, peer-to-peer

I-Share Deliverable 3.7: Design of the Tribler P2P-TV Client

Authors: A. Bakker, J.A. Pouwelse, S. Koolen, J. Roozenburg, J. Yang, Y. Yuan

Abstract: This deliverable describes the current design of the Tribler BitTorrent client that is being developed as part of the I-Share project. It provides detailed specifications for each of the client's new features to enable others to create compatible implementations. It also describes the list of possible new features that will be designed and implemented in subsequent versions. This deliverable will be updated yearly to yield a complete design of an I-Share system at the end of the project. The previous version of this document is deliverable D3.104.

Fbref: Freeband/I-Share/D3.7v1.0

Where: I-Share Deliverable.

Keywords: peer-to-peer, bittorrent

I-Share Deliverable 3.8: Interactive 3D Video Rendering Using Service Sharing Technology

Authors: S. Chen, J.J.Lukkien, R.Verhoeven, R. Bosman, M. Tjiong, G. Petrovic, P.H.N. de With

Abstract: This document describes the joined work of SAN and ELE of TU/e on the I-Share project prototype demonstration D3.8, including an introduction to the example scenario, system design and implementation. Work described in this document is the first phase of I-Share D3.8. The demonstrator is expected to have three phases that extend each-other. Similarly, this document will have three versions

Fbref: Freeband/I-Share/D3.8v1.0

Where: I-Share Deliverable.

Keywords: 3d video, interactive rendering, service sharing

I-Share Deliverable 3.9: Third Version of the P2P-TV Client

Authors: A. Bakker, J. Roozenburg, M. ten Brinke, J. Mol J. Yang, L. Musat, F. van der Werf, M. Meulpolder, F. Zindel, I. Haratcherev

Abstract: This document accompanies the release of the third version of the Tribler peer-to-peer TV client. This version was released to the public on October 11, 2007 and carries Tribler version number 4.1.7.

Fbref: Freeband/I-Share/D3.9v1.0

Where: I-Share Deliverable.

Keywords: peer-to-peer, television, bittorrent

I-Share Deliverable 3.10: Design of the Tribler P2P-TV Client

Authors: A. Bakker, J. Roozenburg, M. ten Brinke, J.J.D. Mol, J. Yang, L. Musat, F. Zindel, F. van der Werf, M. Meulpolder, J. Taal, J.A. Pouwelse

Abstract: This deliverable describes the current design of the Tribler peer-to-peer TV client that is being developed as part of the I-Share project. It provides detailed specifications for each of the client's new features to enable others to create compatible implementations. It also describes the list of possible new features that will be designed and implemented in subsequent versions. This deliverable will be updated yearly to yield a complete design of an I-Share system at the end of the project. The previous version of this document is deliverable D3.7.

Fbref: Freeband/I-Share/D3.10v1.0

Where: I-Share Deliverable.

Keywords: peer-to-peer, P2P-TV, bittorrent

I-Share Deliverable 3.11: Prototype of secure service discovery and access in virtual communities

Authors: S. Chen, J. Lukkien, R. Verhoeven, R. Bosman, J. Middendorp

Abstract: This document describes the work of SAN of TU/e on the I-Share project prototype demonstration D3.11. Work described in this document is an extension of I-Share D3.8. Previous work adressed applications composed of shared services. Current work integrates the virtual community concept with the service composition. Future work will take the resource constraints into account to make an application capable of context dependent behaviours.

Fbref: Freeband/I-Share/D3.11v1.0

Where: I-Share Deliverable.

Keywords: service discovery, virtual communities

I-Share Deliverable 3.13: Final Version of the P2P-TV Client

Authors: A. Bakker, J. Roozenburg, M. ten Brinke, J.J.D.Mol, J. Yang, F. Zindel, F. van der Werf, M. Meulpolder, L. d'Acunto, B. Zhang, A. Abbas, N. Neubauer, R. Rahman, D. Hales, V. Heinink, R. Petrocco, D. Rabaioli, J. Taal, J.A. Pouwelse

Abstract: This document accompanies the release of the final version of the Tribler peer-to-peer TV client.

Fbref: Freeband/I-Share/D3.13v1.0

Where: I-Share Deliverable.

Keywords: peer-to-peer, television, bittorrent

I-Share Deliverable 3.14: Final Design of the Tribler P2P-TV Client

Authors: A. Bakker, J. Roozenburg, M. ten Brinke, J.J.D.Mol, J. Yang, F. Zindel, F. van der Werf, M. Meulpolder, L. d'Acunto, B. Zhang, A. Abbas, N. Neubauer, R. Rahman, D. Hales, V. Heinink, R. Petrocco, D. Rabaioli, J. Taal, J.A. Pouwelse

Abstract: This deliverable completes the design of the Tribler peer-to-peer TV client that was developed as part of the I-Share project. Together with deliverable D3.104, D3.7 and D3.10 it forms the complete design. As the previous deliverables, it provides detailed specifications for each of the client's new features to enable others to create compatible implementations. It includes the full specification of the Application Programming Interface (API) of the Tribler system.

Fbref: Freeband/I-Share/D3.14v1.0

Where: I-Share Deliverable.

Keywords: peer-to-peer, televison, bittorrent

I-Share Deliverable 3.17: Prototype of resource-aware and reliable free view point 3D video streaming in virtual communities.

Authors: Shudong Chen, Johan J. Lukkien, Richard Verhoeven, et al.

Abstract: In this demonstrator, multimedia services, including 3D video streaming services and display services are shared then composed into distributed applications in a virtual community. Using the access control of the virtual community, the secure sharing of these services can be achieved. During the 3D video streaming over a fix network and a mobile network, capacity of the delivery channel and resource limitation of the underlying devices are being taken into account. Video encoding protocols can adapt to the real states of these mediums. And delivery protocols are matched with the coded video 3D format to facilitate enhanced reliability and robustness.

Fbref: Freeband/I-Share/D3.17v1.0

Where: I-Share Deliverable.

Keywords: demonstrator, resource-aware, 3D video streaming, virtual community.

WP4

I-Share Deliverable 4.1: A Small-Scale Field Trial with Tribler

Authors: J.J.D. Mol, A. Bakker, D.H.J. Epema

Abstract: This deliverable describe the lessons learned from a small-scale experiment with streaming a live concert at the Paradiso concert hall to ADSL users using Tribler.

Fbref: Freeband/I-Share/D4.1v1.0

Where: I-Share Deliverable.

Keywords: live streaming, experiment, ADSL

I-Share Deliverable 4.2: Enhanced Tribler version 4.0

Authors: J. Roozenburg, J. Yang, M. ten Brinke, D. Epema, Jan David Mol

Abstract: In May 2007 version 4.0 of the I-Share Tribler P2P software was released as I-Share deliverable D4.2. During the development of this software release many features of Tribler were enhanced resulting in a mature P2P video client. This document provides an overview of the most important of these enhancements, distinguished into those that were specifically created for valorization, and those created in the context of the research in I-Share.

Fbref: Freeband/I-Share/D4.2v1.0

Where: I-Share Deliverable.

Keywords: tribler, peer-to-peer, valorization

I-Share Deliverable 4.3: Report on the Tribler workshop May 2007

Authors: F. Zindel, J. Taal, D. Epema

Abstract: At the same time as the release of Tribler 4.0, the Tribler team held an invitation-only workshop on May 23, 2007, in Cristofori in Amsterdam. The workshop was attended by about 60 people from various industries and countries. The workshop also coincided with the final stages of the writing of the P2P-Next EU project proposal and many of the P2P-Next partners (e.g., Pioneer, STM, BBC) were present at the workshop. The first half of the workshop program featured speakers from research departments in the industry and broadcasters, who provided their insight on the future of P2P technology. The second half of the workshop program was focused on business cases for P2P technology. In addition to the presentations, several technology partners gave demonstrations of their use of Tribler technology. The media reported extensively about the Tribler 4.0 release. Especially the online media in many countries wrote about our project.

Fbref: Freeband/I-Share/D4.3v1.0

Where: I-Share Deliverable.

Keywords: tribler, workshop report

I-Share Deliverable 4.5: Overview of Business Models with Tribler

Authors: J. Taal, F. Zindel, J. Pouwelse, D. Epema

Abstract: The Tribler Peer-to-Peer (P2P) program is innovative software for sharing and distributing content. It is developed as a research vehicle for P2P technology, virtual communities, recommendation and P2P-TV. The interest from the outside world for Tribler and its technologies led to starting the Tribler Valorization project, for which 4 goals were defined: 1. Enhanced, well-documented and customizable version of Tribler. 2. Dissemination of the underlying technology of Tribler. 3. Field Trials with Tribler. 4. Business plan for the continued use and development of Tribler after the Freeband program finishes. During the development and contacts with industry and with public and private broadcasters, we have gained a better feeling for the wishes and demands of the industry but also of how an open-source platform such as Bittorrent and Tribler can disrupt the content market. In this report we investigate and evaluate business models in which Tribler can play role.

Fbref: Freeband/I-Share/D4.5v1.0

Where: I-Share Deliverable.

Keywords: tribler, business models, valorization

I-Share Deliverable 4.6: Tribler Customization Features

Authors: F. Zindel, J. Taal, A. Bakker, J. Roozenburg

Abstract: This document gives an overview of the customizability features of Tribler, which consist of a modification of the Tribler Architecture with a P2P core and the design and implementation of the corresponding Application Programming Interface (API). These features are added as part of the Tribler valorization project. In this project we try to enhance Tribler in order to make it possible to interconnect with existing third-party systems, and to build Tribler derivative technologies for use in commercial applications. To discover which customizability features would most benefit Tribler Valorization we surveyed our current business partners for their most urgent customizability needs. The results of this survey led to two tracks of customizability in Tribler. The first track of customizability features allows third parties to modify the lookand- feel of Tribler and its graphical user interface. The second track of customizability features allows our business partners to modify the Tribler algorithms' behavior. This document can also be used as a first lead to understand the internals of Tribler before starting to customize it. Some examples will clarify how to customize the Tribler Client.

Fbref: Freeband/I-Share/D4.6v1.0

Where: I-Share Deliverable.

Keywords: Tribler, customization, Tribler Core, Tribler API

I-Share Deliverable 4.7: Evaluation of the Tribler Course

Authors: J. Taal, F. Zindel

Abstract: On May 27th 2008, a successful course on Advanced Tribler Technology was held. Guests from industry and from collaborating partners from other research projects attended the course. This document contains an evaluation of the course.

Fbref: Freeband/I-Share/D4.7v1.0

Where: I-Share Deliverable.

Keywords: tribler technology, peer-to-peer background, live streaming

I-Share Deliverable 4.8: Enhanced Tribler Version 2

Authors: A. Bakker, J. Yang, J. Mol, J. Roozenburg, M. ten Brinke, I. Haratcherev

Abstract: This document accompanies the release of the enhanced version 2 of the Tribler peer-to-peer TV client.

Fbref: Freeband/I-Share/D4.8v1.0

Where: I-Share Deliverable.

Keywords: tribler, peer-to-peer, valorization

I-Share Deliverable 4.9: A Business plan for using Tribler outside Freeband

Authors: J. Taal

Abstract: This deliverable is a complete Business Plan for a service based on Tribler Technology.

Fbref: Freeband/I-Share/D4.9v1.0

Where: I-Share Deliverable.

Keywords: business plan

I-Share Deliverable 4.12: A Large-Scale Field Trial with Tribler

Authors: J.J.D. Mol, A. Bakker, J.A. Pouwelse, D.H.J. Epema en H.J. Sips

Abstract: With peer-to-peer (P2P) technology, a video can be streamed from its source to a large number of clients at low cost. P2P technology lowers the distribution cost for the source by having the clients forward the video stream among each other. As a consequence, the quality of service of one client is partially determined by the behaviour and characteristics of the clients providing it with the video stream. We have extended BitTorrent, a popular P2P protocol, to support both live video streaming and video-on-demand. Since the behaviour and characteristics of end users are hard to predict, we choose to evaluate our modifications by deploying them. We implemented our modifications in Tribler, our social P2P client. We invited thousands of users to participate in our trials, by all watching the same video stream. In this deliverable, we present the setup and results of these trials for the video-on-demand subsystem. Most of the users obtained a good video quality after only a minimal delay.

Fbref: Freeband/I-Share/D4.12v1.0

Where: I-Share Deliverable.

Keywords: bittorrent, live streaming, trial

I-Share Deliverable D4.13: First Version of the SwarmPlayer

Authors: A. Bakker, J.J.D. Mol, J. Roozenburg, M. ten Brinke, J. Pouwelse

Abstract: This document accompanies the first release of the SwarmPlayer, an easy-to-use video player for ondemand and live content based on the Tribler peer-to-peer television technology.

Fbref: Freeband/I-Share/D4.13v1.0

Where: I-Share Deliverable.

Keywords: live streaming, BitTorrent

I-Share Deliverable 4.14: A business showcase of a Tribler product of service.

Authors: J. Taal

Abstract: Although already many television-type applications for the web exist, such as YouTube, Joost, Vuze, none have all the properties required for replacing the linear TV-channel model. This deliverable describes a business concept that does possess all these properties.

Fbref: Freeband/I-Share/D4.14v1.0

Where: I-Share Deliverable.

Keywords: business showcase

I-Share Deliverable 4.15: A Lessons Learned workshop on valorization

Authors: J. Taal, F. Zindel, D. Epema

Abstract: On October 28th, Tribler team organized a successful lessons-learned workshop on valorization, coined "Tribler in the Real World".

Fbref: Freeband/I-Share/D4.15v1.0

Where: I-Share Deliverable.

Keywords: workshop, valorization

I-Share Deliverable 4.16: Evaluation of the Valorization of Tribler

Authors: D.H.J. Epema, J.R. Taal, F. Zindel

Abstract: In early 2006, the first version of the Tribler P2P client developed in the context of the Freeband I-Share research project attracted much interest from external parties such as broadcasting companies, internet companies, and set-top box manufacturers. As a consequence, the Tribler valorization project was started towards the end of 2006 as a separate work package of I-Share. The overall goal of this valorization project was to make Tribler live on in one form or another after I-Share has finished in December 2008. In this report we evaluate the Tribler valorization efforts. We discuss the initial goals, we present our achievements obtained in the context of Tribler valorization, and we draw conclusions based on these experiences.

Fbref: Freeband/I-Share/D4.16v1.0

Where: I-Share Deliverable.

Keywords: valorization, evaluation

Templates

• I-Share 2005 version of Powerpoint template for presentations.
• Freeband 2005 version of Powerpoint template for presentations.
• LaTeX template for I-Share deliverables 2006.
• Powerpoint template for Freeband Event scientific posters.

Private

To get a copy of a deliverable, or any other private I-Share document, contact Arno Bakker by email at A.Bakker@few.vu.nl.