Throughput-Smoothness Trade-offs in Multicasting of an Ordered Packet Stream

TL;DR

This paper analyzes the trade-offs between throughput and smoothness in multicasting ordered packet streams to two users over erasure channels, proposing coding schemes to optimize different points on this trade-off.

Contribution

It introduces a Markov chain model for analyzing in-order delivery and proposes coding schemes to balance throughput and smoothness in multicasting scenarios.

Findings

Markov chain model effectively characterizes delivery trade-offs

Coding schemes can optimize different points on the throughput-smoothness spectrum

Analysis applies to two-user multicast over erasure channels

Abstract

An increasing number of streaming applications need packets to be strictly in-order at the receiver. This paper provides a framework for analyzing in-order packet delivery in such applications. We consider the problem of multicasting an ordered stream of packets to two users over independent erasure channels with instantaneous feedback to the source. Depending upon the channel erasures, a packet which is in-order for one user, may be redundant for the other. Thus there is an inter-dependence between throughput and the smoothness of in-order packet delivery to the two users. We use a Markov chain model of packet decoding to analyze these throughput-smoothness trade-offs of the users, and propose coding schemes that can span different points on each trade-off.