shed the first white paper for 5G architecture and launched several 5G projects, including 5G- Crosshaul, 5G Exchange (5GEx), flex5Gware, and SPEED-5G [1]. The NGMN alliance identified several UCs, scenarios, and business models for 5G and their requirements. Moreover, ETSI participates on standardizing the mobile or multi- access edge computing (MEC) technology and NFV. Meanwhile, 3GPP publishes several technical standards to identify the essential specifications and regulations for the 5G NR. In addition, it provides solutions for the vertical market such as automotive, transport, industry, and e-health. Considering several enhancements are still ongoing for the 5G eco-system, 3GPP develops release 17 to be completed in 2021. On the other hand, O-RAN alliance [2] aims at providing open, virtualized, and artificial intelligence (AI)-powered RAN. 1.1.1 Review of Related 5G Surveys The state of the art on the 5G technology has been discussed in several surveys such as [3-20] and research works cited therein. This chapter addresses three main 5G topics involving 5G public and private architectures, key 5G enabling technologies, and 5G development and projects. Considering these topics, Table 1.1 presents and compares the scope, contributions, and limitations of the most relevant research works for the scope of this chapter. The 5G architectural frameworks and challenging issues have been explored in several surveys such as in [3-8]. Habibi et al. [3] investigated comprehensively the 5G cloud-RAN (C-RAN) architecture. However, the 5G architecture in [3] addressed C-RAN for mobile operators or public networks considering remote radio head (RRH) and baseband unit (BBU). Similar to [3], Hossain et al. [4] reviewed several challenging issues and research works on enhancing C-RAN, including throughput, interference, energy efficiency, latency, and SO on. In addition, the scope of [5] focused on reviewing extensively the resource allocation challenges A Comprehensive Study on 5G Table 1.1 Review for the most relevant surv