Understanding the Performance Gap Between Pull-Based Mesh Streaming Protocols and Fundamental Limits

Pull-based mesh streaming protocols have recently received much research attention, with successful commercial systems showing their viability in the Internet. Despite the remarkable popularity in real-world systems, the fundamental properties and limitations of pull-based protocols are not yet well understood from a theoretical perspective, as there exists no prior work that studies the performance gap between the fundamental limits and the actual performance. In this paper, we develop a unified framework based on trellis graph techniques to mathematically analyze and understand the performance of pull-based mesh streaming protocols, with a particular focus on such a performance gap. We show that there exists a significant performance gap that separates the actual and optimal performance of pull-based mesh protocols. Moreover, periodic buffer map exchanges account for most of this performance gap. Our analytical characterization of the performance gap brings us not only a better understanding of several fundamental tradeoffs in pull-based mesh protocols, but also important insights on the design of practical streaming systems that can achieve high streaming rates and short initial buffering delays.