## 2 The Evolution from Cloud Computing to MEC
### Edge Computing
#### 2.3.2 Mobile Edge Computing Architecture  
In this section, some MEC architectures that have been proposed in the last decade are reviewed. * Mobile Micro Cell (MMC)  
Making sure that applications such as augmented reality and video streaming work smoothly is a big challenge for current technologies. The MMC solution, described in [50], puts a server right in the BS, so devices such as smartphones connect directly for super-fast access to resources. The MMC has ultra-low delays and does not need central control, but it faces challenges such as handling disruptions and balancing the load. * Small Cell Cloud (SCC)  
SCC uses small cell RANs in cellular systems, like LTE, with small BSs covering short distances. The aim is to boost the efficiency of these networks since user devices are nearby. In SCC, Small Cell Managers (SCMs) enhance the capabilities of BSs, making it easier to manage resources dynamically. This setup allows for powerful computing at the network edge, but coordinating BSs and deploying SCMs optimally is still a challenge. In a model for MEC using SCC, authors, in [51], considered multiple users, geographically spread data centers, and provider profits, using the NSGA II algorithm [52] to balance user satisfaction, identifying a Pareto front [53] and provider benefits. However, mobility was not addressed. * MobiScud  
Network service providers have begun to use highly distributed mobile network architectures, utilizing new technological approaches such as NFV and SDN, to reach goals such as scalability, flexibility, and low latency of future applications [54]. Further limitations such as backhaul adaptability and standards compatibility make the process of deploying a cloud-based architecture like cloudlets in cellular networks even more laborious. Moreover, some services and applications, such as cognitive augmentation and smart healthcare, need to exchange sensitive and private information quickly between devices (UEs) and the cloud. MobiScud is designed to handle these limitations and problems. In [54], the authors use a method from an earlier work on the SMORE architecture [55]. This method moves certain data to an internal cloud platform without changing how standards for interactions work, using SDN features. SDN features help send low-latency, high-computation applications to a private Virtual Machine (VM) platform. To move specific data to a private VM in the cloud for user applications that need low latency, the MobiScud control function cooperates with the main network, the cloud operator, and the SDN plane. * Follow Me Cloud (FMC)  
A new method to implement collaborative services in mobile networks is a networked federated cloud [56] to effectively support mobile users' demands in relation to the geographical coverage and proximity of DCs to UEs. It includes allocating virtual resources provided on several distributed DCs over a particular geographical region, upon the infrastructure of different federated cloud providers in a transparent way. To address the modern tendency of cloudifying the mobile network infrastructure and providing mobile services in a flexible manner, it is crucial to take into account user needs, the availability of in-region resources, and the flexibility of the virtualization methods on which federated clouds are built [57]. The concept of federated clouds is to connect the geographically dispersed DCs into a shared resource pool to provide various cloud services. When a service request is received, a DC is selected to handle it through the network. It is crucial to spread cloud resources in different places to be closer to users, which makes serving tasks faster and have lower communication cost. To handle requests optimally, a special process guides the request to the best DC based on available resources, user requirements, and expected QoS. This process also moves the service to other DCs if needed.