I. Introduction
Cloud computing has made tremendous success in the past decade, which provides powerful, scalable, and reliable computing and storage for average users and enterprises. However, when it comes to the mobile computing, the clouds cannot meet the requirements of mobility support and low response time for many mobile applications, due to the large geographic distances between the clouds and the end devices. Mobile edge computing (MEC) [1] has been proposed as a new architecture for dealing with the issue. It pushes the computation capability and data storage from cloud to the edge nodes which are at the proximity of the end devices, such that the end devices can enjoy the computing and data access services with low latency.