Order Optimal Coded Caching-Aided Multicast under Zipf Demand Distributions.
Mingyue Ji, Antonia Maria Tulino, Jaime Llorca, Giuseppe Caire · arXiv (Cornell University) · 2014
Caching and multicasting are two key technologies for reducing traffic load in content delivery networks. While uncoded caching based delivery schemes can offer competitive performance under skewed popularity distributions, the use of coded transmission schemes of increased complexity has been recently shown to significantly improve multicast efficiency under flatter popularity distributions, by exploiting coded multicast opportunities created by simple cooperative caching policies. In this paper, we consider a caching network with one source, hosting m files, connected to n destinations, each with a storage capacity of M files, via a shared link. Given that file requests follow a Zipf popularity distribution, our objective is to characterize the minimum average number of transmissions to satisfy all user demands in the information theoretic sense. We present both achievable coded caching-aided multicast schemes and outer bounds for this network configuration and show that as m,n → ∞, for any M , the achievable average number of transmissions and the outer bound meets up to a constant factor.