Coding for Fast Content Download

TL;DR

This paper investigates how coding and data distribution across multiple disks can significantly reduce content download times by leveraging redundancy and parallel access models.

Contribution

It introduces a theoretical analysis of download time trade-offs in coded storage systems under different access models, providing explicit and bounded characterizations.

Findings

Coding reduces download time by increasing data diversity across disks.

Explicit characterization of download time for fountain model.

Bounds on download time for fork-join model.

Abstract

We study the fundamental trade-off between storage and content download time. We show that the download time can be significantly reduced by dividing the content into chunks, encoding it to add redundancy and then distributing it across multiple disks. We determine the download time for two content access models - the fountain and fork-join models that involve simultaneous content access, and individual access from enqueued user requests respectively. For the fountain model we explicitly characterize the download time, while in the fork-join model we derive the upper and lower bounds. Our results show that coding reduces download time, through the diversity of distributing the data across more disks, even for the total storage used.