China Unicom were early adopters of C-RAN. On the global stage, C-RAN architecture-related equipment crossed $5 billion in market share as early as 2015 (https: //www.fiercewireless. com/tech/ihs-china-fuels-5b-c-ran-market). AT&T adopted C-RAN at a later stage, in preparation for mmWave and 5G (https://www.fiercewireless.com/wireless/ -t-lays-c-ran-foundation-preparation-for-5g). - In Europe, Nokia and Ericsson drove the adoption of C-RAN starting in 2015. Globally speaking, Huawei and Samsung are the other two large companies adopting C-RAN. As a result, global revenues related to C-RAN exceeded $12 billion by 2020. In summary, the adoption of C-RAN can lead to a higher density of cell services under 5G, reduced CAPEX and open costs by using BBU pooling, and reduced energy consumption, leading to improved Environmental, Social, and Governance (ESG) outcomes for companies. In the next section, we will look at O-RAN. Understanding O-RAN Open RAN or O-RAN is a vastly popular term in the 5G network world. It deals with the interoperability of open hardware, software, and interfaces for cellular wireless networks. The goal is to allow the use of Commercial Off-The-Shelf (COTS) servers and network equipment as opposed to customer hardware similar to those used in the base stations. In other words, O-RAN is a movement to standardize and allow for the interoperability of RAN's building blocks (https://www.viavisolutions.com/ en-us/solutions/o-ran). 5G Infrastructure Design O-RAN provides flexibility for operators to mix and match vendor equipment and not get locked into particular propriety hardware, software, and interfaces. See Figure 12.8: What is Open RAN? Radio Open Interface Access Network Centralized Unit (CU) - 5G Core and Distributed Unit (DU) Automation (RAN) Figure 12.8 - A simplified view of O-RAN O-RAN promotes a more vibrant supply chain ecosystem for 5G compared to its predecessors due to the use of open standards for communication. This adds agility to the innovation process for the network and its appl