Introduction

Caching has attracted significant attention recently because it holds the promise of scaling the service capability of mobile networks. Modern mobile networks are capable of achieving data rates of Gbps, yet they may still fail to meet the predicted bandwidth requirements of future mobile applications. A recent report from Cisco [1] forecasts that mobile data traffic will grow to 77.49 EB per month in 2022. In theory, a human brain may process up to 100 T bits per second. Even though this does not necessarily reflect the ultimate bandwidth required by a human being, a huge gap between bandwidth demand and provisioning may still exist in the near future. Unfortunately, on-demand transmission which dominates current mobile network architectures has almost achieved its performance limits revealed by Shannon in 1948. Because of this and other limitations it is time to envision paradigm-shifting mobile network architectures for the sixth generation (6G) of mobile networks [2]. Cache-aided mobile networking is regarded as one of the potential solutions for beyond fifth generation (5G) systems. Caching techniques were originally developed for computer systems in the 1960s. Web caching was conceived for the Internet due to the explosively increasing number of websites in the 2000s. In contrast to on-demand transmission, caching allows proactive content placement before being requested, which has motivated some novel infrastructures such as information-centric networks and content delivery networks. More recently, caching has been found to substantially benefit data transmissions over harsh wireless channels and meet growing demands with restrained radio resources. The key purpose of this book is to introduce the cutting-edge theory and techniques in the area of edge caching for mobile networks. In this chapter, we shall present a brief overview of the technical content of this book. In particular, this book mainly covers five major topics belonging to edge caching for mobile networks. They are fundamental limits of caching, asymptotic analysis of caching in large mobile networks, resource allocation for edge caching, caching with time-varying popularity and recommendation systems, and some typical applications of edge caching.