Coding for caching: Fundamental limits and practical challenges

Caching is an essential technique to improve throughput and latency in a vast variety of applications. The core idea is to duplicate content in memories distributed across the network, which can then be exploited to deliver requested content with less congestion and delay. The traditional role of cache memories is to deliver the maximal amount of requested content locally rather than from a remote server. While this approach is optimal for single-cache systems, it has recently been shown to be significantly suboptimal for systems with multiple caches (i.e., cache networks). Instead, cache memories should be used to enable a coded multicasting gain. In this article, we survey these recent developments. We discuss both the fundamental performance limits of cache networks and the practical challenges that need to be overcome in real-life scenarios.