1 Introduction
Edge computing [1], [2] has been widely accepted as a promising technology for supporting resource constrained mobile users (or end devices) to run computation-intensive while delay-sensitive Internet-of-Things (IoT) applications, such as natural language processing, virtual reality, facial recognition, interactive entertainment, healthcare monitoring and crowdsensing. Different from the traditional cloud computing systems (e.g., AWS, AliCloud and Azure)[3], in which public cloud servers are usually located far away from mobile users and have to be reached through wide area networks, edge computing, in contrast, enables computing capabilities at ubiquitous wireless access points (e.g., small-cell base stations) so that more flexible, agile and convenient supplementary computing services can be provided to mobile users whenever they encounter computational burdens [4].