While the overall bandwidth of peer-to-peer live video streaming system scales automatically as peers collectively contribute the bandwidth, each peer also demands to download at the specified video playback rate so as to play the video smoothly. Therefore, a fundamental problem arisen is how to balance the bandwidth supply and demand in the peer-to-peer system to enjoy peers with the best video quality.To address this problem, we propose a fully distributed peer-topeer video streaming framework which automatically adapts the network towards full bandwidth utilization. Our design possesses two unique features. First, a special link-level homogenous overlay network is formed in which all the overlay links approach to have an identical bandwidth value. With such a feature, video flowing through the overlay links will not encounter any bottlenecks, and peers can thus achieve the guaranteed downloading rates. Second, based on the peer downloading rate observed locally at the streaming server, the server can adaptively adjust the video playback rate so that peers can achieve the best video quality with full bandwidth utilization. The effectiveness of our framework is verified through extensive simulations.

In this paper we propose an adaptive P2P video streaming framework to address the challenges due to bandwidth heterogeneity and peer churn on the Internet. This adaptive streaming framework consists of two major components, source rate adaptation and adaptive overlay topology formation, to maximize the video quality and fully utilize the overall peer upload capacity. In the source rate adaptation, the video server adapts the video source rate automatically based on the local measurement of peers' download rates, so that the P2P network is not overloaded beyond its bandwidth Parts of the results in this paper have been presented in capacity and peers are able to achieve smooth video playback. To combat bandwidth heterogeneity, we propose to construct a desirable link-level homogeneous overlay topology using a Markov chain Monte Carlo method, so that peers achieve an equal per-connection upload/download bandwidth. In this link-level homogeneous network, video flows do not encounter any bottlenecks along the delivery paths, and peers achieve high download rates to ensure smooth video playback. We also design a fully distributed algorithm to implement the dual mechanisms of the adaptive topology formation and the source rate maximization. To evaluate the performance of our streaming framework, we conduct both mathematical analysis and extensive simulations. The simulation results confirm our analysis and show that the proposed distributed algorithm is able to maximize the video playback quality with fast convergence.

Among the existing P2P systems for content distribution, BitTorrent (BT) is the most popular one which has attracted keen attentions from both industrial and academic forces in recent years. Its superior performance is due to the multipart downloading scheme by dividing the large file into thousands of small blocks to enable the cooperative downloading among participants. Since transmissions are provoked by interested blocks only, the block distribution will seriously affects the performance of the system, i.e., robustness and throughput. As a result, how to manage the circulation of blocks is important both theoretically and practically. BT leverages on the Local Rarest First scheme to pursue the even distribution of blocks to help peers locate what they need easily. Surprisingly, how good is its performance with heterogenous networks has never received research attention before and this motivates our work. In this study, we carried out simulations to investigate the evolution of block distribution in BT. We find that the block distribution is far from optimal in terms of block frequency (with some blocks dominating the network and some becoming extinct nearly) and topology (with same blocks tending to conglomerate). We also propose a simple source coding mechanism to achieve a BT like network with much improved performance in this view.

In this paper, we consider the fairness issue of BT and tackle the problem with a general framework using proactive topology adaptations. The topology formed possesses a special link-level homogeneity property with each peer having the same capacity per out-degree value. Such property guarantees that each directional link has the same uploading bandwidth. Together with the Tit-for-Tat policy, peers upload and download at the same rate over each connection and therefore achieve fairness.