Predictive caching at the wireless edge using near-zero caches

In this paper, we study the effect of predictive caching on the delay of wireless networks. We explore the possibility of caching at wireless end-users where caches are typically very small, orders of magnitude smaller than the catalog size. We develop a predictive multicasting and caching scheme, where the Base Station (BS) in a wireless cell proactively multicasts popular content for end-users to cache, and access locally if requested. We analyze the impact of this joint multicasting and caching on the delay performance. Our analysis uses a novel application of Heavy-Traffic theory under the assumption of vanishing caches to show that predictive caching fundamentally alters the asymptotic throughput-delay scaling. This in turn translates to a several-fold delay improvement in simulations over the on-demand unicast baseline as the network operates close to the full load. We highlight a fundamental delay-memory trade-off in the system and identify the correct memory scaling to fully benefit from the network multicasting gains.