On the Cost of Cloud-Assistance in Tree-Structured P2P Live Streaming

摘要

Consider a cloud-assisted Peer-to-Peer (P2P) video streaming system, in which a given video stream of a unit bit rate is divided into several stripes and is delivered to all subscribing peers through different spanning trees of height two each, with the aid of the cloud bandwidth. We call such a low latency delivery of stripes a 2-hop delivery of the stripes. In this paper, we prove that if the average upload bandwidth of the peers equals to one and the video stream is divided into a stripes, then 2-hop delivery of the stream to n subscribing peers is possible if the additional bandwidth provided by the cloud is at least 2n/a. This result indicates that the cloud assistance is effective to realize a scalable, dependable P2P video streaming system, while the cost of cloud assistance can be arbitrarily small as the number of stripes increases.