On heterogeneous user demands in Peer-to-Peer video streaming systems

A Peer-to-Peer (P2P) video streaming system usually consists of a large number of peers, which have heterogeneous physical properties. Orthogonal to the physical heterogeneity, there is another type of heterogeneity called demand heterogeneity. Namely, peers have their own demands on the quality and type of the streaming service. The problem of demand heterogeneity has received little attention and as a result current P2P video streaming systems cannot achieve satisfactory performance due to demand heterogeneity. In this dissertation, we study how to design efficient P2P video streaming systems with heterogeneous user demands. First, we study the problem of heterogeneous user demands on video quality. We design an efficient P2P live streaming system which greatly reduces the bandwidth consumption and still achieves satisfactory streaming quality. To reduce the bandwidth consumption, we use adaptive streaming, so that the streaming rate of a peer is commensurate with its window size. In order to maintain satisfactory streaming quality even in the case when peers dynamically change their window sizes, small-window peers are designed to contribute part of their bandwidth to help large-window peers. Second, we study the problem of heterogeneous user demands on playback delay. Specifically, we consider time-shifted streaming service and bounded-delay live streaming service. With time-shifted streaming service, a peer can watch a program which has been broadcast live before it joins the system. We propose a cooperation-based prefetching design which distributes video segments more widely in a P2P streaming system and thus greatly improves the streaming quality. With bounded-delay live streaming service, some peers (e.g., paid users) can watch the program with short and bounded playback delays, and other peers (e.g., free users) with best-effort short playback delays. We prove that the bounded-delay live streaming problem is NP-Complete, and propose a heuristic algorithm which constructs an efficient P2P overlay structure of peers by considering their playback delay requirements and their physical properties. The promising results in this dissertation show that our algorithms are effective in meeting heterogeneous user demands on video quality and playback delay. In the future, we are interested in designing efficient P2P streaming systems in mobile and cloud environments