I. Introduction
With the rapid development of wireless communications, there is a huge increase in the data generated in future networks. Simultaneously, the advanced storage and computing technologies strongly demand real-time data processing [2], [3]. Motivated by this trend, mobile edge cloud (MEC), which is also known as mobile edge computing, has emerged as an effective technology to alleviate these issues by placing multiple edge servers proximate to the base station (BS) [4]. The benefits of the MEC system are twofold: i) improve bandwidth utilization and energy efficiency for communications; ii) reduce transmission delay and the demand for backhaul links. In recent years, MEC has attracted increasing attention in wireless communications, predicted to increase by 26.4% annually from 2022 to 2026 [5].