Heterogeneity in Distributed Live Streaming: Blessing or Curse?

TL;DR

This paper explores how heterogeneity in distributed live streaming systems can either improve or hinder performance, showing that while single chunk delay can benefit from heterogeneity, streaming delay may suffer unless the system is slightly overprovisioned.

Contribution

It introduces models for chunk atomicity in heterogeneous systems and demonstrates conditions under which heterogeneity is beneficial or detrimental for streaming delay.

Findings

Heterogeneity speeds up single chunk delay compared to homogeneous systems.

Heterogeneity can cause arbitrarily larger delays for streaming multiple chunks.

Overprovisioning allows near-optimal streaming delay in heterogeneous systems.

Abstract

Distributed live streaming has brought a lot of interest in the past few years. In the homogeneous case (all nodes having the same capacity), many algorithms have been proposed, which have been proven almost optimal or optimal. On the other hand, the performance of heterogeneous systems is not completely understood yet. In this paper, we investigate the impact of heterogeneity on the achievable delay of chunk-based live streaming systems. We propose several models for taking the atomicity of a chunk into account. For all these models, when considering the transmission of a single chunk, heterogeneity is indeed a ``blessing'', in the sense that the achievable delay is always faster than an equivalent homogeneous system. But for a stream of chunks, we show that it can be a ``curse'': there is systems where the achievable delay can be arbitrary greater compared to equivalent homogeneous systems. However, if the system is slightly bandwidth-overprovisioned, optimal single chunk diffusion schemes can be adapted to a stream of chunks, leading to near-optimal, faster than homogeneous systems, heterogeneous live streaming systems.