A Tutorial on O-RAN Deployment Solutions for 5G: From Simulation to Emulated and Real Testbeds

The Open Radio Access Network (O-RAN), manifested through the specifications established by the O-RAN Alliance, stands ready to transform the telecommunications ecosystem. In particular, the O-RAN Alliance reference architecture proposes hierarchical structures supported by several interfaces, including non-real-time and near-real-time functions. Non-real-time functions, denoted as rApps, encompass services, configurations, policy management, and RAN analytics. Conversely, near-real-time applications, denoted as xApps, serve as an open compute edge platform hosting applications from multiple vendors. Therefore, understanding the testing and deployment processes of rApps and xApps is pivotal for both researchers and practitioners. In this tutorial, we evaluate different 5G RAN deployments to determine the state of the art of available open-source solutions and assess their readiness for real cloud continuum environments by targeting solutions for simulation, emulation, and real testbeds. This tutorial empowers developers to gain a comprehensive understanding of O-RAN technologies, their development, and operations, enabling them to make well-informed choices for their target technologies. It considers both qualitative and quantitative benchmarks, as well as use cases, and facilitates a seamless transition of applications from simulated environments to real-world scenarios. Moreover, this tutorial provides a hands-on guide on setting up and migrating an xApp from a simulated environment to a real testbed. It includes a guide on deploying Service Management, Orchestration, and Non-Real-Time RAN Intelligent Controller and rApp. Finally, we identify existing open challenges and trace future directions to enhance the availability, portability, reliability, and configurability of 5G RAN deployments.