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Optimal Scheduling of File Transfers with Divisible Sizes on Multiple Disjoint Paths  [PDF]
Mugurel Ionut Andreica
Computer Science , 2008,
Abstract: In this paper I investigate several offline and online data transfer scheduling problems and propose efficient algorithms and techniques for addressing them. In the offline case, I present a novel, heuristic, algorithm for scheduling files with divisible sizes on multiple disjoint paths, in order to maximize the total profit (the problem is equivalent to the multiple knapsack problem with divisible item sizes). I then consider a cost optimization problem for transferring a sequence of identical files, subject to time constraints imposed by the data transfer providers. For the online case I propose an algorithmic framework based on the block partitioning method, which can speed up the process of resource allocation and reservation.
Wireless Peer-to-Peer Scheduling in Mobile Networks  [PDF]
Michael J. Neely
Computer Science , 2012,
Abstract: This paper considers peer-to-peer scheduling for a network with multiple wireless devices. A subset of the devices are mobile users that desire specific files. Each user may already have certain popular files in its cache. The remaining devices are access points that typically have access to a larger set of files. Users can download packets of their requested file from an access point or from a nearby user. Our prior work optimizes peer scheduling in a general setting, but the resulting delay can be large when applied to mobile networks. This paper focuses on the mobile case, and develops a new algorithm that reduces delay by opportunistically grabbing packets from current neighbors. However, it treats a simpler model where each user desires a single file with infinite length. An algorithm that provably optimizes throughput utility while incentivizing participation is developed for this case. The algorithm extends as a simple heuristic in more general cases with finite file sizes and random active and idle periods.
Extended Equal Service and Differentiated Service Models for Peer-to-Peer File Sharing  [PDF]
Jianwei Zhang,Yongchao Wang,Wei Xing,Dongming Lu
Computer Science , 2012, DOI: 10.1109/JCN.2013.000037
Abstract: Peer-to-Peer (P2P) systems have proved to be the most effective and popular file sharing applications in recent years. Previous studies mainly focus on the equal service and the differentiated service strategies when peers have no initial data before their download. In an upload-constrained P2P file sharing system, we model both the equal service process and the differentiated service process when peers' initial data distribution satisfies some special conditions, and also show how to minimize the time to get the file to any number of peers. The proposed models can reveal the intrinsic relations among the initial data amount, the size of peer set and the minimum last finish time. By using the models, we can also provide arbitrary degree of differentiated service to a certain number of peers. We believe that our analysis process and achieved theoretical results could provide fundamental insights into studies on bandwidth allocation and data scheduling, and can give helpful reference both for improving system performance and building effective incentive mechanism in P2P file sharing systems.
Minimizing weighted sum download time for one-to-many file transfer in peer-to-peer networks  [PDF]
Bike Xie,Mihaela van der Schaar,Richard D. Wesel
Mathematics , 2010,
Abstract: This paper considers the problem of transferring a file from one source node to multiple receivers in a peer-to-peer (P2P) network. The objective is to minimize the weighted sum download time (WSDT) for the one-to-many file transfer. Previous work has shown that, given an order at which the receivers finish downloading, the minimum WSD can be solved in polynomial time by convex optimization, and can be achieved by linear network coding, assuming that node uplinks are the only bottleneck in the network. This paper, however, considers heterogeneous peers with both uplink and downlink bandwidth constraints specified. The static scenario is a file-transfer scheme in which the network resource allocation remains static until all receivers finish downloading. This paper first shows that the static scenario may be optimized in polynomial time by convex optimization, and the associated optimal static WSD can be achieved by linear network coding. This paper then presented a lower bound to the minimum WSDT that is easily computed and turns out to be tight across a wide range of parameterizations of the problem. This paper also proposes a static routing-based scheme and a static rateless-coding-based scheme which have almost-optimal empirical performances. The dynamic scenario is a file-transfer scheme which can re-allocate the network resource during the file transfer. This paper proposes a dynamic rateless-coding-based scheme, which provides significantly smaller WSDT than the optimal static scenario does.
Investigating the User Behavior of Peer-to-Peer File Sharing Software  [cached]
Shun-Po Chiu,Huey-Wen Chou
International Journal of Business and Management , 2011, DOI: 10.5539/ijbm.v6n9p68
Abstract: In recent years, peer-to-peer file sharing has been a hotly debated topic in the fields of computer science, the music industry, and the movie industry. The purpose of this research was to examine the user behavior of peer-to-peer file-sharing software. A methodology of naturalistic inquiry that involved qualitative interviews was used to collect data from 21 university students in Taiwan. The results of the study revealed that a substantial amount of P2P file-sharing software is available to users. The main reasons for using P2P file-sharing software are to save money, save time, and to access files that are no longer available in stores. A majority of respondents use P2P file-sharing software to download music, movies, and software, and the respondents generally perceive the use of such software as neither illegal nor unethical. Furthermore, most users are free-riders, which means that they do not contribute files to the sharing process.
Adaptive Event Dissemination for Peer-to-Peer Multiplayer Online Games  [PDF]
Gabriele D'Angelo,Stefano Ferretti,Moreno Marzolla
Computer Science , 2011, DOI: 10.4108/icst.simutools.2011.245539
Abstract: In this paper we show that gossip algorithms may be effectively used to disseminate game events in Peer-to-Peer (P2P) Multiplayer Online Games (MOGs). Game events are disseminated through an overlay network. The proposed scheme exploits the typical behavior of players to tune the data dissemination. In fact, it is well known that users playing a MOG typically generate game events at a rate that can be approximated using some (game dependent) probability distribution. Hence, as soon as a given node experiences a reception rate, for messages coming from a given peer, which is lower than expected, it can send a stimulus to the neighbor that usually forwards these messages, asking it to increase its dissemination probability. Three variants of this approach will be studied. According to the first one, upon reception of a stimulus from a neighbor, a peer increases its dissemination probability towards that node irrespectively from the sender. In the second protocol a peer increases only the dissemination probability for a given sender towards all its neighbors. Finally, the third protocol takes into consideration both the sender and the neighbor in order to decide how to increase the dissemination probability. We performed extensive simulations to assess the efficacy of the proposed scheme, and based on the simulation results we compare the different dissemination protocols. The results confirm that adaptive gossip schemes are indeed effective and deserve further investigation.
Availability of titles on peer-to-peer file sharing networks  [PDF]
Petrus H. Potgieter
Computer Science , 2012,
Abstract: File sharing, typically involving video or audio material in which copyright may persist and using peer-to-peer (P2P) networks like BitTorrent, has been reported to make up the bulk of Internet traffic. The free-riding problem appears in this "digital gift economy" but its users exhibit rational behaviour, subject to the characteristics of the particular network. The high demand for the Internet as a delivery channel for entertainment underlines the importance of understanding the dynamics of this market, especially when considering possible business models for future pricing or licensing regimes and for the provisioning of network capacity to support future services. The availability of specific titles on file sharing networks is the focus of this paper, with a special emphasis on the P2P protocol BitTorrent. The paper compares the incentives provided in BitTorrent to those in other file-sharing communities, including file hosting, and discusses the number of titles available in the community at any given time, with an emphasis on popular video items with ambiguous legal status.
On Optimal File Distribution in Practical Mesh-Based Overlay Networks  [cached]
Xiao Su,Yan Bai,Suchreet K. Dhaliwal
Journal of Communications , 2010, DOI: 10.4304/jcm.5.9.703-714
Abstract: Distributing large video files or operating system images over the Internet requires file servers with high bandwidth and large storage capacity. Overlay networks, including content distribution networks (CDN) and peer-to-peer (P2P) systems, are promising network models for large file distributions. Both CDN and P2P leverage bandwidth and storage resources between content distribution servers and individual nodes, so that they can scale to a larger number of nodes easily. Previous work on large file distribution mainly focused on minimizing the distribution time of a fully connected overlay network. In a fully connected overlay network, each individual node is connected to every other node in the network. However, most practical CDN and P2P systems are based on a partially connected mesh topology, where nodes are typically connected to a subset of other nodes. In this paper, the distribution time of practical mesh-based overlay systems is analyzed and a lower bound on the file distribution time is established. Our algorithms consist of two steps. First, we decompose the mesh network into multiple spanning trees so that the load on each node is balanced. We show that the construction of balanced spanning trees is NP-complete and propose a few heuristics to tackle it. The second step, we derive the optimal system distribution time based on the multiple spanning tree topology, node bandwidths and file size. In this step, an optimal file segmentation algorithm is developed, in which a file is divided into unequal-sized pieces and allocated to individual nodes based on the available bandwidth. We validate our theoretical analysis via experiments and investigate how system design parameters, such as node churning and implementation complexity, affect system distribution time.
A Lightweight Model for Mobile Peer-to-Peer File Sharing Systems  [cached]
George Stephan,Badieh Traboulsi,Rabih Dbouk,Sanaa Sharafeddine
Journal of Advances in Information Technology , 2010, DOI: 10.4304/jait.1.2.67-72
Abstract: Peer-to-peer file sharing applications such as BitTorrent, Gnutella, and eDonkey are becoming widely utilized using desktops and handheld mobile devices. In this paper, we propose a lightweight model for peer-to-peer file sharing systems using mobile devices. The proposed model splits the peer-to-peer mobile client into two main modules: a mobile module that runs on the mobile device and a gateway module that runs separately on a dedicated server. In order to reduce computational requirements and energy consumption, the gateway server handles the connections to distributed peers over the Internet and downloads the required chunks of a requested file. The mobile device then simply connects to the gateway server to check the status of the download process and to get the requested file as soon as the download is complete. Therefore, the gateway relieves the mobile device from searching and downloading the file chunks. We present the general design and prototype implementation of the proposed model.
A Peer-to-Peer Browsable File Index using a Popularity Based Global Namespace  [PDF]
Thomas Jacobs,Aaron Harwood
Computer Science , 2007,
Abstract: The distribution of files using decentralized, peer-to-peer (P2P) systems, has significant advantages over centralized approaches. It is however more difficult to settle on the best approach for file sharing. Most file sharing systems are based on query string searches, leading to a relatively simple but inefficient broadcast or to an efficient but relatively complicated index in a structured environment. In this paper we use a browsable peer-to-peer file index consisting of files which serve as directory nodes, interconnecting to form a directory network. We implemented the system based on BitTorrent and Kademlia. The directory network inherits all of the advantages of decentralization and provides browsable, efficient searching. To avoid conflict between users in the P2P system while also imposing no additional restrictions, we allow multiple versions of each directory node to simultaneously exist -- using popularity as the basis for default browsing behavior. Users can freely add files and directory nodes to the network. We show, using a simulation of user behavior and file quality, that the popularity based system consistently leads users to a high quality directory network; above the average quality of user updates. Q
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