Distributed Caching and Small Cell Cooperation for Fast Content Delivery
Weng Chon Ao, Konstantinos Psounis · 2015
Modern wireless devices such as tablets and smartphones are pushing the demand for higher and higher wireless data rates. The vast majority of this demand comes from media content. In this paper we propose to combine two recent ideas, distributed caching of content in small cells, and, cooperative transmissions from nearby base stations/BSs (generally known as coordinated multi-point), to achieve unprecedented content delivery speeds while reducing backhaul cost and delay. A key characteristic of our architecture is the interdependence between the caching strategy and the PHY/MAC layer coordination. Specifically, the caching strategy may cache different content in nearby BSs to maximize the hit ratio, or cache the same content in multiple nearby BSs such that the corresponding BSs can transmit concurrently, e.g. to multiple users using zero force beamforming, and achieve multiplexing gains. With this in mind, given the popularity distribution of the content, the available cache size, and the network topology, we devise optimal strategies of caching such that the throughput of the system is maximized. Our analytical and simulation results show that our system yields significantly faster content delivery, which, under realistic scenarios and assumptions can be one order of magnitude faster than that of legacy systems.