Joint Cache-Channel Coding over Erasure Broadcast Channels

TL;DR

This paper studies a cache-aided broadcast system over erasure channels, showing how joint cache-channel coding and unequal cache sizes enhance efficiency during high congestion.

Contribution

It introduces a joint cache-channel coding framework for erasure broadcast channels and characterizes the tradeoffs between rate and cache size, highlighting benefits of unequal caches.

Findings

Joint cache-channel coding improves communication efficiency.

Unequal cache sizes benefit systems with varying channel qualities.

Tradeoffs between rate and cache size are characterized.

Abstract

We consider a cache-aided communications system in which a transmitter communicates with many receivers over an erasure broadcast channel. The system serves as a basic model for communicating on-demand content during periods of high network congestion, where some content can be pre-placed in local caches near the receivers. We formulate the cache-aided communications problem as a joint cache-channel coding problem, and characterise some information-theoretic tradeoffs between reliable communications rates and cache sizes. We show that if the receivers experience different channel qualities, then using unequal cache sizes and joint cache-channel coding improves system efficiency.