# 5G NPN Performance Evaluation for I4.0 Environments
## 1 Introduction  
The emergence of twin transition paradigms in multiple technological fields with the introduction of 5G telecommunication standards in recent years [1] has led to a rapid convergence between the telco and industrial domains [2]. Industrial domains and factory spaces include a large variety of heterogeneous devices with stringent communication requirements and complex topologies involving different processes. This renders the use of public telco networks (i.e., public 5G infrastructure) challenging, as factory floor operators usually require full control of the underlying network and total provision of the corresponding resources [3]. This has led to the introduction of 5G Non-Public Networks (NPNs) for industry protocols and operations; however, the evolutionary shape of 5G networks and their modular architecture requires an equal plug-and-play functionality in each environment for proper adaptation. The Reference Architectural Model Industry 4.0 (RAMI 4.0) [4] paradigm defines such a modular factory environment, and sets a solid groundwork for the further adaptation of 5G networks to the industry floor. I4.0 has opened up various fields and technological candidates to drive innovation and progress [5, 6]; in terms of communication, 5G meets the necessary requirements to support such a demanding environment. From the first Industrial Revolution (I1.0), where the introduction of water- and steam-powered machines helped workers to carry out their tasks, the increased efficiency and capability necessitated growth in other areas--businesses grew from individual interests to organizations with owners, managers, and employees serving customers. In I2.0, electricityreplaced water and steam as the primary power source, and enabled the concentration of power sources to fewer machines and, eventually, machines having their own power sources. Paralleling mechanical innovation was the innovation in workforce organization when I3.0 occurred, in the last few decades of the 20 th century, known as the first computer era. The invention of devices such as the transistor and, later, the integrated circuit chip made it possible to fully automate machines to further aid or entirely replace human operators. Software systems were developed to make complete use of the new possibilities created by electronic hardware. Integrated manufacturing systems were replaced by enterprise-scale planning tools, which allowed users to plan, schedule, and track product flows. This convergence into I4.0 must also address a wider set of topics related to real-time response problems, energy efficiency, performance, privacy, and security--topics covered in detail previously [7]. Within the scope of this paper, 5G NPN deployments are used to evaluate the real-time response criticality of I4.0, 5G, and performance. Nonetheless, security and privacy are vital components of every 5G NPN setup, and the proposed integration with IDS primitives addresses this aspect partially in the proposed work. 5G has already been applied in industry-related scenarios and setups [6; 7; 8; 9; 10; 11; 12], mainly focusing on wireless communication acceleration and multipoint connectivity--features that can essentially boost factory floor operations in a seamless manner. Apart from the use of 5G fast-path communications to replace wiring [10; 11], the I4.0 vision outlines how unified automation and holistic provision can also push forward innovation in industrial fields [12; 13; 14]. The key enabler in this unified namespace evolution of I4.0 is OPC UA [14]. OPC UA is a unified industrial component dictionary and communication specification that aims to combine different vendor protocols and prototypes in a homogeneous manner for industrial Asset Administration Shell (AAS) systems. This manuscript proposes a hybrid OPC UA and 5G convergence to a prototype AAS for I4.0 as a stepping stone for 5G communications on the plant floor.