The rapid adoption of Internet of Things (IoT) technologies and digital twins (DTs) is revolutionizing smart cities by facilitating improved real-time monitoring, simulation, and optimization of urban infrastructures. In data centers, digital twins offer virtual representations of physical infrastructure, enabling real-time monitoring, optimization of energy consumption, cooling efficacy, and resource utilization. This integration seeks to improve energy efficiency and sustainability in smart cities. In this context, edge computing is becoming essential solutions to mitigate latency, bandwidth, and privacy issues linked to centralized cloud system. A significant challenge in utilizing digital twins for edge-enabled data centers is attaining accurate time synchronization between the digital twin and its physical equivalent. Precise synchronization is crucial for real-time state representation, facilitating efficient monitoring, control, and optimization. The distributed characteristics of edge devices, varying network conditions, and constrained computational resources present considerable synchronization challenges. Factors such as clock drift, network jitter, and protocol constraints can result in temporal inconsistencies, compromising the reliability of digital twin applications. This paper offers an extensive examination of time synchronization issues in digital twins for edge-enabled data centers within smart city contexts. The study examines essential factors affecting synchronization accuracy and reliability, identifies significant bottlenecks, and suggests strategies to alleviate their impact. The results aid in the creation of effective synchronization mechanisms, facilitating the implementation of dependable digital twin systems.

The Industry 4.0 has led to a significant transformation in manufacturing and industrial processes, characterized by increased connectivity and widespread digitalization. This revolution is driven by the convergence of IT (Information Technology) paradigms with OT (Operational Technology) domains. Virtualization technology plays a crucial role in this integration, thanks to its characteristics of agility, scalability, and efficiency. This work investigates the virtualization of Programmable Logic Controllers (PLCs) and it is focused on the need for evaluating their performance. PLCs are essential components of industrial automation and are being virtualized to increase flexibility, reduce hardware dependencies, and enable seamless integration with IT infrastructures. This work proposes a methodology for evaluating the execution time of a benchmark program and the PLC real-time behavior. Experiments on a real use case demonstrate that the PLCs implemented in containers may be 50 times faster than the real ones in executing data elaboration, while no significant differences were observed in real-time communication. In any case, virtual PLCs are characterized by greater jitter with respect to real PLCs.

The demand for enhanced flexibility in automation systems, dictated by initiatives as the Industry 4.0 in Europe or the Industrial Internet Consortium in the United States, can be satisfied inheriting solutions of the information technology (the so called IT-OT convergence). Other than communication and cloud technologies, virtualization will play a relevant role in the next future. The use of lightweight virtualization, e.g., in the form of containers for implementing the edge computing paradigm, is a promising tool to dynamically provide services depending on the actual production needs. However, requirements of industrial automation applications are different from those of office-like counterparts. For this reason, methodologies for evaluating obtainable performance are needed. In this work, an industrial-grade framework, the Siemens Industrial Edge, is considered. A reference testbed is setup to evaluate latencies when information is exchanged between two user applications. Experiments demonstrate that round trip time in the order of 10 ms is feasible, compatible with the requirements of both process control systems and supervision applications.

LPWAN, an acronym for Low Power Wide Area Network, addresses all the wireless communication solutions aiming at maximize the lifetime of battery powered end devices by means of high-sensitivity radios and sporadic data transactions. Among the different members of the LPWAN family, LoRaWAN is an emerging solution satisfying requirements of many Internet of Things (IoT) related applications. LoRa WAN supports both public and private deployments, operating in unlicensed frequency bands. Handling critical messages, e.g., originated after emergency events in industrial plants, is out of the original LoRaWAN scope. For this reason, the LoRa-REP replication scheme was proposed to increase reliability and to reduce latency of confirmation. In this work, obtainable performance are further improved allowing frame overlaps in time and frequency, exploiting LoRa virtual channels. In particular, Software Defined Radio paradigm is exploited for implementing a proof-of-concept to be used in real-world trials. The preliminary results, supported by simulations as well, are discusses, confirming the feasibility and effectiveness of the proposed approach.

Low Power Wide Area Networks (LPWANs) are wireless technologies well accepted in the Internet of Things (IoT) scenarios because they operate in both public and private infrastructure using unlicensed frequency bands. Differently from other wireless standards, the LPWAN target applications are low-rate, sporadic-transmission, low-energy systems. Surely, fast response time and high reliable communication are out of the original LPWAN scope. In this work, a first investigation about the use LoRaWAN (one the most diffused LPWAN protocols) for notification of emergency messages across industrial plants is reported. The opportunity of using recently proposed low-cost repeaters, and the creation of a clever replication pattern of radio messages are the keys of the proposed approach. The results of the preliminary analytical feasibility assessment are presented, confirming the possibility to increase success ratio of notification and respective confirmation in case of emergencies.

Recently, designers of the home automation framework are looking to the Internet of Things (IoT) model to make it easier to deploy devices capable of gathering data from various plants. This situation is pushing a further evolution: from the conventional building automation, where the logic is determined by the installer or by the customer, to a cognitive system, capable of learning from the customers' preferences what the best plant configuration would be. The aim of this research work is to identify issues related to the implementation of cognitive solutions during the renovation process of buildings. The paper proposes a cognitive framework to help the operation and management phases of buildings, by means of the digitalization of the supply chain of the construction industry, from the single building aspect to the entire construction cycle. The paper presents the design of smart building elements with integrated capability to generate a massive amount of data for monitoring the energy and maintenance status of renovated buildings. The IoT paradigm has been used to link the physical word of building elements with the cognitive layer. The proposed approach has been applied and validated into a real test case.

The LoRaWAN technology, an example of low power wide area network, is considered a possible IoT-derived solution for realizing private cellular (single-hop) communications in the industrial domain. However, despite LoRaWAN promises long range and dense environments with many obstacles (as the industrial ones), it may suffer from coverage issue. Additionally, the inverse relationship between data rates and range may be unacceptable for many industrial applications. In this article, an innovative LoRaWAN range extender (based on an enhanced LoRaWAN node) is described, and its integration in the infrastructure of industrial Internet of Things (IIoT)-enabled industrial wireless networks is presented. A frame relay strategy is suggested, thus avoiding to tradeoff the highest data rates against an increased sensitivity. The feasibility of the solution is formally verified and the features of the realized proof-of-concept prototype, based on commercially available hardware, are discussed. The experimental results, obtained with a purposely designed test bench, show the effectiveness of the proposed approach. In particular, the range extender is transparent for legacy LoRaWAN networks as confirmed by correct relaying of uplink and downlink for different types of LoRaWAN message.

In the last decade, the growth of the economic, automotive and technological sectors, has been notable. Alongside this growth, emerges the term ”Industry 4.0” which is used to represent the current Industrial Revolution. This revolution involves different areas: from manufacturing to healthcare. Industry 4.0 can create value during the entire product lifecycle, promoting customer feedback and having the entire product history throughout its life. The automatic communication between vehicle and factory was facilitated, allowing the accomplishment of different analysis regarding vehicles, such as the identification of a behavioral pattern through historical driver usage, fuel consumption, maintenance indicators and so on. This would allow the prevention of critical issues and undesired behaviors as it prevents the automakers from losing contactwiththe vehicle after the purchase. This paper aims to propose a customer feedback platform for vehicle manufacturing in Industry 4.0 context, capable of collecting and analyzing, through an OBD-II scanner the sensors available in vehicles, with the purpose of assisting in the management, prevention, and mitigation of different vehicular problems. An intercontinental experiment conducted in locations within Brazil and Italy show the feasibility of the platform and the potential to use preliminary results in order to improve the vehicle manufacturing.

Smart Grids deployment is growing around the world. The expansion of the existing Smart Grid network infrastructure in order to connect new electrical substations (or end-users) may be impaired by difficult cable deployment. For this reason, recently, wireless communication links have also been used. This paper deals with the deployment, and the first characterization, of an IEEE 802.11ac connection between IEC 61850 electrical automation devices. Some configurations of IEEE 802.11ac have been tested and compared with usual cable connection. The use of GPS based instrumentation combined with IEEE 1588 clock synchronization allows reducing measurement uncertainty and producing meaningful results. For instance, the IEC 61850 Transfer Time between GOOSE (Generic Object Oriented Substation Event) publisher and subscriber over an IEEE 802.11ac wireless link, loaded with 80Mbit/s of traffic, has an average value of 5.4 ms and a maximum value of 10 ms.

Micro grids are localized groups of electricity generators, energy storage systems, and loads with the possibility of operating both connected and disconnected from the distribution grid. This paper is focused on the automation of micro grids using heterogeneous communication networks; the new approach takes into account the need of reusing existing wired and wireless technologies and assets when planning and deploying new renewable power sources or energy storage systems into traditional (old) grids. The proposed system uses the IEC 61850 in order to guarantee the interoperability with the distribution grid. In addition, the possible synergies with industrial and building automation have been investigated using well-known automation protocols (such as PROFINET and Modbus TCP). The proposed system has been installed and tested in a real micro grid inside the campus of the University of Brescia. Design description, deployment report and result analysis are given, showing that the performance of the real system (i.e. reaction time less than 30 ms at grid level network over heterogeneous links) is in line with the application requirements.

Large industrial automation networks based on Real-Time Ethernet protocols may need efficient multicast management and filtering in order to control traffic load and to guarantee the desired quality of service. Very often industrial network are required to be highly available, implying the use of redundancy protocols, and thus, the use of dynamic (layer 2) multicast reconfiguration may be effective. This paper evaluates the application of standard IEEE Multiple MAC registration Protocol (MMRP) to industrial automation scenarios. Two main application fields are considered: large (and slow) process automation plants; and fast factory automation networks inside electric substations for measuring and protection. Following analytical and simulation approaches complete model of MMRP has been developed. Last, a new set of protocol parameters is proposed to maximize effectiveness of MMRP in industrial scenarios: a great network load reduction and a multicast reconfiguration time of 40 ms after a fault can be obtained in networks with complex topology.

The increased need for power quality monitoring and active control of distribution grid necessitates the introduction of the Smart Grid (SG) approach, requiring an efficient ICT system for the monitoring and control of distribution grid state. The main obstacle to deployment of SG in real system is the lack of an efficient communication infrastructure. The use a heterogeneous network, which employs various technologies, appears to be the most promising solution. Nevertheless, the management of these communication systems has proven to be hard and error prone. In this paper, a Software Defined Networking (SDN) approach has been proposed to manage SG communication system applied to grid monitoring/supervision. The preliminary feasibility analysis is promising, although a more detailed modeling and analysis of the system is needed due to the extreme heterogeneity of the network.

Real-time networks for substations automation systems are based on ICT technologies and they may take great advantages from ultra recent network technological improvements. A careful evaluation of the performance enhancement is required. Due to cost and system complexity, such an analysis can be performed only using a dedicated simulation environment, but the currently available simulation libraries are not focused on lower layers (L1, PHY, and L2 MAC). The main objective of this work is to introduce the architecture of a modular network simulator, with suitable models of L1 and L2 Ethernet layers, for the simulation and co-simulation of substation automation Real-time Ethernet networks. The modular simulator includes interfaces for both co-simulation with FPGA-hardware board and real network, and co-simulation with automation application software (e.g. IEC61850 SCADA system, etc.).

The paper describes the application of an improved Time Gateway for simplifying the integration of old IEC 61850 devices in new IEC 61850 Substation Automation System with IEEE 1588 PTP. Old devices typically retrieve time information with the well-known SNTP protocol which uses very different time representations and synchronization strategies with respect to PTP. Hence, the paper uses a transparent, full-software, Time Gateway for interfacing SNTP devices with a PTP synchronization domain, demonstrating its applicability by means of a prototype based on an FPGA. Experimental results show the Time Gateway improves the overall performance with respect to an SNTP-only system. Moreover, the experiments demonstrate that the synchronization accuracy is limited by the SNTP.

Several types of industrial Real-Time Ethernet (RTE) networks could be present in the same plant. This work deals with the clock synchronization problems that arise when different RTE network infrastructures are interconnected. Specifically, this paper is focused on the exploitation of PROFINET IO Conformance Class C infrastructure for the interconnection of other industrial communication devices or measurement instruments that use IEEE1588 for clock synchronization. Actually, such devices (e.g., LXI instruments, EtherNet/IP devices, etc.) cannot be satisfactorily synchronized if directly connected to the PROFINET infrastructure, because of the large time errors (up to 100 μs). The solution proposed in this paper is an intelligent clock synchronization converter that has fewer limitations if compared with other systems, like boundary clocks. The basic idea is the creation of a “black-box” (a sort of remote bridging device) for the interconnection of IEEE1588 nodes through a PROFINET IO host plant, with zero-configuration on both systems. The proposed approach differs from boundary clock since its goal is to keep the PROFINET IO and the IEEE1588 synchronization domains separated, exploiting the possibility to tunnel the IEEE1588 time information through the PROFINET IO infrastructure with sufficient precision. In order to verify the practical feasibility of the proposed solution, LXI Class B instruments have been connected to the infrastructure of a real PROFINET IO network. The results show that the standard deviation of the synchronization accuracy is only 10 ns higher than the one measured in the case of a dedicated (separated) network for the LXI instruments.

The paper deals with IEEE1588 PTP-based devices which are installed in industrial plants together with PROFINET IO Class C. In fact, devices with PTP for clock synchronization (e.g. LXI instruments, Ethernet/IP nodes etc.) exhibit noticeable time errors if directly connected to the PROFINET infrastructure. In the paper, possible architectures to overcome this limitation are evaluated (i.e boundary clock), then an intelligent clock synchronization converter is proposed. The core idea is to create a black-box that does not require configuration neither of the PTP-based nodes nor of the host plant. The proposed converter has been applied to a PROFINET IO network that hosts PTP-based devices. Preliminary results show that, if compared with a direct connection of PTP-based nodes, the converter worsens the synchronization accuracy of less than 10 ns.