# 5G New Radio Open Radio Access Network Implementation in Brazil: Review and Cost Assessment
## 1 Introduction  
The Radio Access Network (RAN) is the primary component of wireless mobile networks. It connects user equipment (UE) to the core network, providing the necessary features and functionalities for end users to engage in mobile communications. The RAN architecture has evolved from the legacy distributed RAN (d-RAN) to the centralized RAN (c-RAN), where the number of equipment units and cost with operation is reduced, and eventually to the virtualized RAN (v-RAN), which provides flexibility to be hosted on data centers and quickly migrated with even more reduced costs in equipment, operation, and maintenance [1]. Though these architectures are robust, they face challenges in meeting the stringent requirements of 5G New Radio (5G NR), especially in terms of very low latency and high reliability for new critical solutions. In Brazil, the infrastructure is not prepared to hold the most advanced technologies, which can delay the implementation of new services and the usage of the 5G NR [2].  
The emergence of v-RAN, a virtualized RAN architecture, demonstrates the industry's innovative approach to addressing these challenges by moving processes to the network edge through separated virtualized network functions. This approach offers flexibility and scalability in the network topology, allowing for implementing new features while meeting requirements [3].  
The RAN represents approximately 70% of the Mobile Network Operator's (MNO) capital expenditure (CAPEX) and operational expenditure (OPEX) in the total cost of ownership (TCO), making it a significant expense. However, introducing Open RAN architectureprovides hope by significantly reducing RAN CAPEX costs. This reduction is achieved by eliminating supplier lock-in through vendor interoperability, utilizing open interfaces, and enabling installation on commercial off-the-shelf hardware (COTS). Open RAN also allows for infrastructure sharing and virtualized radio access equipment deployment in shared data centers or public clouds [4].  
The enablement of the 5G network poses the most significant challenge for MNOs in rural areas with low user penetration, low average return per user (ARPU), and non-existent coverage of mobile radios. The high OPEX and infrastructure complexity in areas with low population density discourage investments in these regions [5].  
Different RAN architectures offer different cost implications. In addition, the cost-effectiveness of each RAN architecture in Brazil depends on various factors, including existing infrastructure, population density, and specific deployment scenarios [6]. This paper discusses the cost considerations of the leading 5G RAN architectures in the context of Brazil, as well as the challenges and opportunities. Focused on Open RAN, this research shows that this technology needs to be implemented. The necessity of increasing the area coverage, reducing the costs for the MNOs, enabling the sharing, and bringing the processing to the network edge are requirements for the new 5G technologies. The information found offers an overview of the actual RAN scenery in Brazil and its evolution over the next few years. It is a base review for new studies and information about Brazil's state-of-the-art implementation. This study is organized as follows: Section 2 discusses 5G New Radio Technology and Open RAN; Section 3 describes the Brazilian landscape; the challenges found in Brazilian deployments are discussed in Section 4; the actual Open RAN implementation in Brazil is demonstrated in Section 5; the implementation costs in Brazil in Section 6; the prospects are presented in Section 7; and conclusion is offered in Section 8.