Audience-Retention-Rate-Aware Caching and Coded Video Delivery with Asynchronous Demands

TL;DR

This paper introduces a new caching and coded video delivery scheme that accounts for asynchronous user demands and audience retention rates, improving efficiency over traditional synchronous models.

Contribution

It proposes a decentralized partial coded caching scheme with two cache allocation strategies that incorporate audience retention, advancing practical coded caching methods.

Findings

The PCC scheme outperforms conventional uncoded caching.

OCA and PCA schemes effectively allocate cache based on retention and popularity.

Numerical results validate the scheme's improved performance.

Abstract

Most results on coded caching focus on a static scenario, in which a fixed number of users synchronously place their requests from a content library, and the performance is measured in terms of the latency in satisfying all of these demands. In practice, however, users start watching an online video content asynchronously over time, and often abort watching a video before it is completed. The latter behaviour is captured by the notion of audience retention rate, which measures the portion of a video content watched on average. In order to bring coded caching one step closer to practice, asynchronous user demands are considered in this paper, by allowing user demands to arrive randomly over time, and both the popularity of video files, and the audience retention rates are taken into account. A decentralized partial coded caching (PCC) scheme is proposed, together with two cache allocation schemes; namely the optimal cache allocation (OCA) and the popularity-based cache allocation (PCA), which allocate users' caches among different chunks of the video files in the library. Numerical results validate that the proposed PCC scheme, either with OCA or PCA, outperforms conventional uncoded caching as well as the state-of-the-art decentralized caching schemes, which consider only the file popularities, and are designed for synchronous demand arrivals. An information-theoretical lower bound on the average delivery rate is also presented.