I. Introduction
With the development of Internet of Things (IoT) and wireless communication technology, more and more devices are connected via the Internet. They generate a huge amount of data, which can be analyzed to provide a better service for us. There are many latency-sensitive applications, such as intelligent medical devices that monitor the vital signs of patients, vehicle-to-vehicle communication that enhances the traffic security by the cooperation among cars, and failure detection of industrial devices that may cost lots of money if the failure lasts for a long time [1].