ACTIVE: Adaptive low-latency peer-to-peer streaming

Peer-to-peer (P2P) streaming is emerging as a viable communications paradigm. Recent research has focused on building efficient and optimal overlay multicast trees at the application level. However, scant attention has been paid to interactive scenarios where the end-to-end delay is crucial. Furthermore, even algorithms that construct an optimal minimum spanning tree often make the unreasonable assumption that the processing time involved at each node is zero. However, these delays can add up to a significant amount of time after just a few overlay hops and make interactive applications difficult. In this paper, we introduce a novel peer-to-peer streaming architecture called ACTIVE that is based on the following observation. Even in large group discussions only a fraction of the users are active at a given time. We term these users, who have more critical demands for low-latency, active users. The ACTIVE system significantly reduces the end-to-end delay experienced among active users while at the same time being capable of providing streaming services to very large multicast groups. ACTIVE uses realistic processing assumptions at each node and dynamically optimizes the multicast tree while the group of active users changes over time. Consequently, it provides virtually all users with the low-latency service that before was only possible with a centralized approach. We present results that show the feasibility and performance of our approach.