I. Introduction
Recently, with the rapid increase of resource-intensive tasks, e.g., augmented reality (AR), Internet of Things (IoT) applications, and autonomous driving, the quality of our life has the potential to be improved greatly. However, due to the limited size and battery life of IoT devices (IoTDs), these applications may be difficult to be implemented in practice. Fortunately, mobile edge computing (MEC) has been proposed recently as a promising technique to liberate IoTDs from computation-intensive tasks by allowing them to offload their high workloads to edge servers [1], [2].