I. Introduction
The past decade has witnessed a significant growth of mobile traffic. Such growth puts tremendous pressure on the paradigm of Cloud-based service provisioning, since moving a large volume of data into and out of the cloud wirelessly requires substantial spectrum resources, and meanwhile may incur large latency. Mobile Edge Computing (MEC) emerges as a new paradigm to alleviate the capacity concern of mobile networks [1]. Residing on the network edge, MEC makes abundant storage and computing resources available to mobile users through low-latency wireless connections, facilitating a number of mobile services like local content caching, augmented reality, and cognitive assistance [2].