Wireless time synchronization of mobile devices is a key enabler for numerous Industry 4.0 applications, such as coordinated and synchronized tasks or the generation of high-precision timestamps for machine learning or artificial intelligence algorithms. Traditional wireline clock synchronization protocols, however, cannot achieve the performance in wireless environments without significant modifications. To address this challenge, we make use of the Reference Broadcast Infrastructure Synchronization protocol, which leverages the broadcast nature of wireless communications and remains both non-invasive and standard-compliant. We implement and validate this protocol on a low-cost testbed using ESP32 modules and a commercial Wi-Fi access point. To support further research and development, we release our implementation as open-source software under the GNU General Public License Version 3 license via the OpenWifiSync project on GitHub1Our results demonstrate that synchronization accuracies within ±30 microseconds are achievable using energy-efficient and affordable hardware, making this approach suitable for a wide range of use cases.

Mobile communication technologies are considered fundamental to the implementation of Industry 4.0, leading to a growing deployment of non-public networks. To effectively manage and monitor these networks, digital twins (DTs) have emerged as a promising solution. The Asset Administration Shell (AAS), as a standardized framework for DTs, offers a structured approach to network monitoring and management. While previous research has demonstrated the feasibility of using AAS in simulated environments, real-world validation remains limited. In this work, we present a technical case study that implements a testbed combining a 5G system with the AAS to monitor license requirements in a non-public network. We evaluate the system’s performance by analyzing responsiveness and demonstrate that the AAS can effectively support real-time monitoring tasks. This study bridges the gap between simulation and practical deployment, highlighting the potential of the AAS for managing 5G network assets in Industry 4.0 contexts.

Precise clock synchronization is an important requirement for distributed and networked industrial use cases. As more and more use cases contain mobile devices, clock synchronization has to be performed over wireless communication links. As wireless communication links are currently not as deterministic and reliable as wireline communication systems, novel clock synchronization algorithms have to be investigated. Here, the so-called Reference Broadcast Infrastructure Synchronization Protocol is a well suited solution as it brings up multiple advantages. Most important is the non-invasiveness, meaning it can be used with commercially available components. As a considerably high amount of factories use Wi-Fi as wireless communication system for their mobile use cases, the aforementioned protocol is implemented using Wi-Fi. Furthermore, the usage of Open-Source Software can be seen as driver for highly efficient and interoperable applications. Consequently, the implementation is accessible under the GNU General Public License on GitHub under the designation OpenWiFiSync. Besides the details on concept, its implementation, and the used testbed, first results are outlined within this paper. Additionally, future work and the estimated timeline are presented.

In order to enable all types of use cases that are proposed within 5G and B5G factory scenarios, an accurate and precise time synchronization is required. Here, the so-called RBIS protocol is a possible solution since it was specifically designed for infrastructure-based wireless communications. While the use of RBIS protocol has a lot of benfits, a strong weakness is its restriction to the range of a single gNB. Thus, a concept for the extension of the RBIS protocol is proposed within this work, as well as a mapping to 5G and B5G systems.In order to prove the suitability of this approach, a simulation that is based on a reference scenario that was specified by NGMN, 3GPP, and IEEE, is carried out. Moreover, as the performance is dependent on the number of users and their mobility, either a tradeoff between minimum number of UEs and performance has to be done, or the usage of dedicated synchronization UEs that are able to guarantee the time synchronization quality.

Smart manufacturing has the objective of creating highly flexible and resource optimized industrial plants. Furthermore, the improvement of product quality is another important target. These requirements implicate more complex control algorithms. Processing these algorithms may exceed the capabilities of resource constrained devices, such as programmable logic controllers (PLCs). In this case, the necessity for computation offloading is given. Due to the fact that industrial plants are currently designed for a life-cycle-time of more than ten years, in a realistic smart manufacturing scenario, these devices have to be considered. Therefore, we investigate the impact of complex algorithms on conventional PLCs by simulating them with a load generator. In addition, we propose a realistic factory scenario including benchmarks for both wireline and wireless communication systems. Thus, their round-trip time (RTT) is measured with and without additional load on the network. With the help of these investigations, break-even points for the application of computation offloading of two typical PLCs of Siemens S7 series can be calculated.

Databases have a huge impact on the functionality of a running system, especially in the context of the Internet of Things (IoT). In the IoT, smart products are created with the usage of neural networks (NN) that require huge amount of stored data for training. The programming language Python is the common way for creating and working with NNs and its data preparation. Therefore, it is useful to use the same language for both, database driver and NN. For this reason, four well-known databases (DBs) are examined for handling different operations. In this paper, the performance of different not only Structured Query Language (NoSQL) DBs (Redis, Cassandra, mongoDB) and MySQL are compared to each other, using most popular Python clients. Important for the performance measurements are not only the actual operation time but also the preparation time that Python or the DB requires to access the data. The results of the paper show that Redis is efficient with small data sets, whereas mongoDB and MySQL are usable for all kinds of data sets, whereas Cassandra handles reading operations well.

Programmable logic controllers (PLCs) are the core element of industrial plants in todays deployments. They read sensor values, execute control algorithms, and write output values. Furthermore, industrial plants have lifetimes of one or more decades. Thus, in a realistic Industry 4.0 scenario, these devices have to be integrated in novel systems. In order to apply advanced concepts and technologies, such as computation offloading, which requires data exchange between PLCs and edge cloud, we investigate open communication interfaces of two typical PLCs of Siemens S7 series. Hence, each of the interfaces is analyzed based on plug & play capability, if metadata is provided, protocol efficiency, and performance. For the latter, the smallest possible update time for each of the interfaces will be measured.

The term Industry 4.0, which refers to the fourth industrial revolution, aims at the digitalization of industries, including all kinds of production assets. With the help of these, so-called "industrial cyber-physical systems", which form the industrial Internet of Things, numerous novel use cases that are key enabler for a smart manufacturing, can be realized. However, existing facilities mainly consist of legacy equipment and technologies that do not offer these kind of flexibility. To address this issue, we introduce an architecture that allows a flexible reconfiguration and redeployment of future process control systems. Moreover, a high system availability and reliability, as required by industrial applications, has been taken into account. The architectural design follows the 4+1 model approach as it is available in the literature. This ensures, that the design results in a holistic architecture. Additionally, we provide insights into first results and outline future development steps.

Industry 4.0 brings up new types of use cases, whereby mobile use cases play a significant role. These use cases have stringent requirements on both automation and communication systems that cannot be achieved with recent shop floor technologies. Therefore, novel technologies such as IEEE time-sensitive networking (TSN) and Open Platform Communications Unified Architecture (OPC UA) are being introduced. In addition, for the realization of mobile use cases, wireline technologies cannot be used and have to be replaced by wireless connections, which have to meet the high demands of the industrial landscape. Here, 5th generation wireless communication system (5G) is seen as a promising candidate.Especially encouraging and similarly challenging is the cooperative work of mobile robots, where particularly high demands on time synchronization arise. Therefore, this paper introduces a concept for the integration of TSN time synchronization (IEEE 802.1AS) conform with 5G to fulfill the requirements of these use cases. Furthermore, the paper describes a testbed for discrete manufacturing, consisting pre-dominantly of industrial equipment, in order to evaluate the presented approach.

Industry 4.0 describes an adaptive and changeable production, where its factory cells have to be reconfigured at very short intervals, e.g. after each workpiece. Furthermore, this scenario cannot be realized with traditional devices, such as programmable logic controllers. Here the use of well-proven technologies of the information technology are conquering the production hall (IT-OT convergence). Therefore, both virtualization and novel communication technologies are being introduced in the field of industrial automation. In addition, these technologies are seen as the key for facilitating various emerging use cases. However, it is not yet clear whether each of the dedicated hardware and software components, which have been developed for specific control tasks and have performed well over decades, can be upgraded without major adjustments. In this paper, we examine the opportunities and challenges of hardware and operating system-level virtualization based on the stringent requirements imposed by industrial applications. For that purpose, benchmarks for different virtualization technologies are set by determining their computational and networking overhead, configuration effort, accessibility, scalability, and security.

The increasing demand for highly customized products, as well as flexible production lines, can be seen as trigger for the “fourth industrial revolution”, referred to as “Industrie 4.0”. Current systems usually rely on wire-line technologies to connect sensors and actuators. To enable a higher flexibility such as moving robots or drones, these connections need to be replaced by wireless technologies in the future. Furthermore, this facilitates the renewal of brownfield deployments to address Industrie 4.0 requirements. This paper proposes representative use cases, which have been examined in the German Tactile Internet 4.0 (TACNET 4.0) research project. In order to analyze these use cases, this paper identifies the main challenges and requirements of communication networks in Industrie 4.0 and discusses the applicability of 5th generation wireless communication systems (5G).