MEC is standardized by ETSI with the industry specification group (ISG) [68]. It aims to provide cloud capabilities and services at the edge servers. Consequently, adopting MEC enhances the QoS, energy efficiency, E2E delay, location awareness and handling of massive number of devices. Figure 1.7 presents an example of the 5G architecture with MEC servers proposed by 5GPPP [45]. Similar to F-CRAN, the architecture of 5GPPP is composed of three tiers, i.e. end-user devices, edge, and cloud. The first-tier of the M. Alfaqawi et al. 5G RAN architecture represents the end-user devices such as automated cars, smart homes, UEs, and SO on. The edge tier represents the NG-RAN that contains the DU, CU, controller, and MEC to provide services for the delay-critical applications. The cloud-tier involves the 5GC and executes the power-hungry and bulky tasks that demand high level of processing. As depicted in Fig. 1.7, the DU and CU might be combined in one unit or separated to have the CU within the MEC and the DU close to the end-user devices. 5 In addition, the CU might be connected to a single or multiple DUs by F1 interface, while the CUs communicate via Xn interface. Moreover, the CU can be decoupled into CU-control plane (CU-CP) and CU-user plane (CU-UP) that facilitates the processing of the control and user planes on different locations. Due to the separation of the CU into CU-CP and CU-UP, the NG interface to communicate with the 5GC is also separated into NG-C or N2 interface and NG-U or N3 interface. The 5G RAN interfaces are presented and explained in [24]. The end-users in Fig. 1.7 can be connected to their corresponding services by network slicing. In this regard, the 5GC eco-system adopts new services such as network slice selection function (NSSF) [46, 74]. The NSSF provides dedicated QoS and application functions (AFs) to interact with the network functions (NFs) [23, 45]. In order to enable network slicing and implement the RAN control func- tions as specific applications (App), 5GPPP provides a controller