A Study of Traffic Locality and Reliability in Peer-to-Peer Video Streaming Applications
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The past decade has witnessed tremendous growth of peer-to-peer (P2P) video streaming applications on the Internet. For these applications, playback smoothness and timeliness are the two most important aspects of users' viewing experiences, whereas the amount of traffic is Internet service providers' main concern. According to the playback delay, video streaming can be classified into on-demand streaming, live streaming, and interactive streaming. P2P live streaming applications typically have an arbitrary number of users, tens of seconds of playback delay, and a high packet delivery rate, but their heavy traffic incurs great financial expenditure and threatens the quality of other services. Interactive streaming applications usually have a small group size, several hundreds of milliseconds of playback delay, and reasonable traffic volume, but cannot achieve a high packet delivery rate. The goal of this thesis is to study traffic locality and reliable delivery of packets in large-scale live streaming and small-scale interactive streaming applications, while keeping the playback delay well below the targeted applications' limits. For P2P live streaming applications, we first identify "typical" schemes from existing P2P live streaming schemes, investigate packet propagation behavior and the impact of neighboring strategies on system performance, and then propose innovative schemes that take both users' viewing experience and traffic locality into consideration. We show that the network-driven tree-based schemes with the swarming technique as a re-transmission error-correction mechanism are superior to the data-driven swarm-based or tree-based schemes, and a properly designed tree-based scheme can localize the traffic while maintaining a high packet delivery rate. For interactive streaming applications, we analyze the efficacy of systematic forward error-correction (FEC) codes against the bursty errors of Internet links when using peers to provide multiple one-hop paths between two communication parties. We find that although using peers for path diversity often results in a lower post-FEC packet loss ratio, some conditions do apply. The interplay of a number of factors, such as the Internet links' error ratio and burst length and the coding parameters, determines the performance of FEC. We provide guidelines and computation methods to determine whether the use of peers for path diversity can be justified.