 layer composed of cross-slice controller (XSC) and intra-slice controller (ISC). The control layer communicates with the RAN NFs via RAN controller agent (RCA) [45]. The RCA, in turns, is located at the CU and used to monitor and store RAN NF information. Accordingly, the controller layer interacts with the RCA via southbound interface (SoBI) in order to collect information regarding UE's power level, link quality, buffer state information, and SO on [45]. Despite the several benefits and popularity of employing MEC within the 5G eco-system, it is still facing several challenges. These challenging issues involve the management of third-party applications, bringing the security and privacy drawbacks of the cloud into the MEC servers, and high maintenance cost in case of MEC failure [20, 75]. 1.2.3 Comparison Among Public 5G Architectures This section compares the various 5G architectures proposed by Telecom bodies and 5G standards for public networks. Table 1.3 compares the 5G architectural frameworks proposed by IBM, O-RAN, and 3GPP with 5GPPP in terms of deployment scenarios, benefits, and limitations. IBM provided the wireless cloud network (WCN) that has been re-explored by China mobile research institute The CU might be deployed as a dedicated hardware or as part of the MEC. 6 The separation of CU-CP and CU-UP occurs via E1 interface. A Comprehensive Study on 5G Table 1.3 Comparison among the 5G architectures proposed by telecommunications bodies Comparison O-RAN alliance and 3GPP 5GPPP with 3GPP Architecture WCN or C-RAN O-RAN NG-RAN with MEC Deployment Fully and partially 6 deployment scenarios in 3GPP in [21] provided scenario centralized C-RAN. In 6 SA and NSA addition, several deployment scenarios. architectures have Meanwhile, 5GPPP been considered based provided an overall 5G on C-RAN such as architecture with H-CRAN, V-CRAN, different and F-CRAN implementation based on various UCs Architecture C-RAN is composed O-RAN is divided into MEC and a controller differences of RU and BBU O-RU, O-DU and O-CU, 