The increasing demand for flexible, cost-effective sensor and control solutions in Industrial Internet of Things (IIoT) environments has led to a growing interest in using OPC UA on embedded microcontrollers. Although existing studies compare OPC UA to other IoT protocols, they often focus on larger boards or high-level development frameworks, leaving a performance gap for smaller devices with limited resources. In this paper, we benchmark version 1.4 of the open62541 OPC UA Client/Server stack on microcontroller-based systems (ESP32, STM32H747) as well as a more powerful edge platform (RevPi Connect 4). We measure round-trip times under varying client counts and polling rates, assessing near real-time capabilities comparable to traditional PLCs. Our results show that the ESP32 and STM32 can support moderate polling loads and a small number of parallel clients, with average latencies generally under 10 ms. For higher client loads and stricter real-time demands, the RevPi platform sustains sub-ms average latencies for up to 100 parallel clients. These findings inform hardware selection and guide industrial practitioners in deploying embedded OPC UA Client/Server solutions for simple sensor-monitoring tasks or more complex edge applications. We discuss implications and limitations of this approach. Finally, future directions in subscription-based communication and implementing standardized data models on resource-constrained devices are discussed.

In this paper, we present the integration of MQTT for Sensor Networks (MQTT-SN) into OPC Unified Architecture (OPC UA) as a novel publish/subscribe (PubSub) protocol binding in order to enhance the industrial communication stack. By leveraging the lightweight MQTT-SN protocol, which is currently not considered in the architecture, we improve OPC UA's capability for high-frequency, low-latency messaging, which is essential for Industrial Internet of Things (IIoT) applications. We discuss related work and describe the design and implementation in detail. Our hybrid approach combines the rich data modeling and security capabilities of OPC UA with the communication efficiency of MQTT-SN, providing a scalable solution for real- time data management in industrial automation systems.

Improved human integration, machine connectivity and decentralized collaborative control systems play an important role in making production systems more flexible. Cyber-Physical Systems for machine control, mobile HMI or SCADA systems are increasingly connected via Internet-based technologies and must also be protected by this open communication technology. Based on a STRIDE analysis, the paper presents proposals on how to secure data exchange between CPS as well as between CPS and mobile HMI using IoT communication, whereby the practicability plays an important role. First results show that the concepts are feasible and are currently undergoing prototypical testing. Future work will focus on the detailed evaluation with respect to communication performance and the determination of the code overhead of the presented solutions.

Due to the increasing complexity of distributed embedded systems, the development process demands early substantiation of design decisions for the targeted system. Virtual prototypes enable an early validation of hardware/software systems and they have proven to be very beneficial for target software development. However, these prototypes often do not include models for inter-device communication aspects of distributed systems. Especially the use of wireless communication has a significant impact on the overall system behavior and performance. This paper introduces a SystemC model of an essential part of IEEE 802.11 Wireless LAN communication, the Enhanced Distributed Channel Access (EDCA) protocol. In comparison to widely used network simulations, the modeling with SystemC promises an easier integration into existing virtual prototypes. EDCA is the main part of the lower medium access layer (MAC) of IEEE 802.11 and interfaces to the physical-layer communication as well as to non-time-critical higher MAC-layer functions. We conducted experiments with an additional simple physical communication channel model to compare our solution in terms of precision and performance to the well-established network simulator ns-3. We show that our model differs by $\approx 0.3 \%$ of retransmitted frames and an accompanied difference of the overall simulated transmission time of $\approx 0.45 \%$. It meets the overall expectations for the stochastic EDCA protocol. Moreover, the presented model has a significantly better simulation performance with $3 \cdot 10^{-5}$ s wall-clock time per frame, which is at least two orders of magnitude better than with the compared ns-3 simulation.

Industrial Internet of Things (IIoT) applications benefit from the knowledge of the device and user positions in a manifold way. Reliable indoor navigation combined with IIoT enables Location-Based-Services (LBS) such as assistance functions of moveable actuators. A crane which follows its operator can significantly increase the efficiency of the process. Safety mechanisms are also enhanced by positioning information. For example, exclusion areas where only automated devices are operating can be implemented. In this paper a novel localization framework is introduced to fuse sensor data from either absolute or relative positioning sources. The core of the framework is an Extended Kalman-Filter (EKF) architecture that is able to handle data from several different sources. Each localization source needs to fulfill requirements regarding data representation and structure defined by the framework, e.g., current state and variance. The approach is verified in a real world scenario with two different sensor types as information sources: Ultra Wide Band localization and Pedestrian Dead Reckoning. We show that the combination of these technologies improves the localization accuracy and evaluate advantages and drawbacks of this approach.

This paper presents a novel decentralized control and communication system targeting diverse set of Material Handling Systems. It is an open platform and based on modular Industrial Device collaboration. The relation of proposed system with Industrial Internet of Things, which have relatively relaxed real time requirements, is also given.

In Smart Buildings there is a large number of connected devices. Each of them is possibly vulnerable, so that an attacker could make use of a single smart device to run attacks in the Smart Building network. We propose a concept to partition the network into trust zones depending on the application layer, so that devices that are logically linked on application layer are able to communicate on MAC layer. A trusted device is used to bootstrap new devices and reconfigure existing trust zones. We restrict the communication as far as possible, so that the potential damage caused by a compromised device is limited. In principle, malicious behavior of devices could lead to an exclusion on MAC layer. The general concept is described using a typical IoT protocol stack containing IEEE 802.11s, IP, UDP/DTLS, and CoAP.

WLAN mesh networks are one of the key technologies for upcoming smart city applications and characterized by a flexible and low-cost deployment. The amendment IEEE 802.11s introduces low-level mesh interoperability at the WLAN MAC layer. On the physical layer, IEEE 802.11n introduced major improvements such as HT data rates, MIMO techniques, and frame aggregation. However, building large-scale 802.11n/s testbeds and reproducible setups is challenging and costly. On the other hand, existing attempts for down-scaling real-world setups are limited to works without support for 802.11n and 802.11s. We therefore present Mini-Mesh, a miniaturized indoor 802.11n/s testbed. Following a transmission range scaling approach, we deploy a 6×6-node mesh grid on an area of only 1 m2. We validate the applicability of our method via comparative measurements, exhibiting a deviation of less than 6 % between a scaled indoor and unscaled outdoor setup. Based on these results, we parameterize a path loss model helping us to estimate outdoor dimensions for arbitrary indoor mesh topologies.

WLAN mesh networks are characterized by their flexible and low-cost deployment, scalability, and self-healing capabilities. The new WLAN standard IEEE 802.11s introduces low-level mesh interoperability. However, building large-scale real-world test beds and reproducible setups is challenging and costly. In the majority of research works, network simulation is preferred over practical measurements. Here, the main disadvantage exists in simplified device and protocol models restricting the comparability to practical implementations. In contrast, using device emulation still requires the simulation of wireless channel and environment models. Consequently, a combination of both emulation and simulation is needed to enable virtual prototyping of real applications and protocols in WLAN mesh networks. Nevertheless, the computation of complex wireless channel effects requires a decoupling of wall clock and simulation time. Therefore, we present ViPMesh, a virtual prototyping framework for IEEE 802.11s and its Linux reference implementation. ViPMesh relies on WLAN device emulation and nested virtualization using QEMU and Linux containers to support the analysis of real applications on top of an unmodified protocol stack. Adopting an alternative time source approach for QEMU, ViPMesh acts as discrete-event simulator. It further integrates channel and environment models with support for IEEE 802.11n MIMO techniques, high throughput modes, multi-channel operation, and node mobility. To the best of our knowledge, this is the first approach that combines the IEEE 802.11s reference implementation with the described simulation features. The functionality of ViPMesh is demonstrated in different example scenarios.

The resource constrained legacy embedded systems are widely found in today's Industrial Control System networks. The Manufacturing message service (MMS) protocol is an international messaging service standard for industrial communications with very limited security provisioning. Legacy embedded systems and real-time applications impose challenges to secure the MMS protocol. Analysing the relevant standards such as IEC 62351-4, this paper presents a secure MMS profile by implementing Transport Layer Security (TLS) into the MMS protocol. In this paper, we present a detailed evaluation of the secure MMS profile that include how TLS addresses the vulnerability of the MMS protocol and an analysis of its performance in a low resource embedded system environment. We found that the secure MMS protocol in legacy embedded systems introduces concerns such as high run-time memory usage and considerable increase of the duration of data read and write. Due to these concerns, real-time nature of applications can be compromised.