Faculté des sciences

Architectures for peer-to-peer media streaming in large scale systems

Schiely, Marc ; Felber, Pascal (Dir.) ; Kropf, Peter (Codir.)

Thèse de doctorat : Université de Neuchâtel, 2009.

The distribution of substantial amounts of data to a large number of clients is a problem that is often tackled by peer-to-peer(P2P)architectures. Bottlenecks are alleviated by distributing the work of the server to all participating peers. Content is no longer passed directly from the server to all clients but only to a small subset of peers from where it is forwarded to a different subset of... Plus

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    Summary
    The distribution of substantial amounts of data to a large number of clients is a problem that is often tackled by peer-to-peer(P2P)architectures. Bottlenecks are alleviated by distributing the work of the server to all participating peers. Content is no longer passed directly from the server to all clients but only to a small subset of peers from where it is forwarded to a different subset of clients. These basic P2P ideas can also be applied to the distribution of live content, such as video streams. Additional timing constraints and bandwidth requirements of this application context lead to new challenges. Peer failures or late arriving packets directly infuence the user perception, which is not the case in simple file distribution scenarios. This thesis first analyzes some of the major problems faced by P2P live media streaming, and then presents a new architecture to address these challenges. Starting from a tree-based approach, the architecture is enhanced with adaptation algorithms to finally evolve in a mesh-based system. The in-depth analysis of tree-based architectures shows that it is important to adapt a node's position in the tree according to its bandwidth capacity. The same analysis is conducted for mesh-based architectures and it is shown that the position on the distribution path has a significant influence on performance. Another important problem concerns the fairness aspect in terms of collaborators and so-called "free-riders". A P2P system works best if all peers contribute with their resources.This can be ensured by tit-for-tat mechanisms where peers return as much as they get. In this thesis a new kind of tit-for-tat mechanism is developed to combine bandwidth contribution with robustness - the more bandwidth a peer provides the more robust its position on the path becomes.