Wireless communication has gained more interest in industrial automation due to flexibility, mobility, and cost reduction. Wireless systems, in general, require additional and different engineering and maintenance tasks, for example cryptographic key management. This is an important aspect that needs to be addressed before wireless systems can be deployed and maintained efficiently in the industry. In this paper, we take an holistic approach that addresses safety and security regardless of the underlying media. In our proposed framework we introduce security modules which can be retrofitted to provide end-to-end integrity and authentication measures by utilizing the black channel concept. With the proposed approach, we can extend and provide end-to-end security as well as functional safety using existing automation equipment and standards, such as Profisafe, Profinet IO, and WirelessHART. Furthermore, we improve the WirelessHART standard with periodic and deterministic downlink transmissions to enable efficient usage of wireless actuators, as well as improving the performance of functional safety protocols.

There are many initiatives and technologies working towards implementing factories of the future. One consensus is that the classical hierarchical automation system design needs to be flattened while supporting the functionality of both Operation Technology (OT) and Information Technology (IT) within the same network infrastructure. To achieve the goal of IT/OT convergence in process automation, an evolutionary transition is preferred. Challenges are foreseen during the transition, mainly caused by the traditional automation architecture, and the main challenge is to identify the gap between the current and future network architectures. To address the challenges, in this paper, we describe one desired future scenario for process automation and carry out traffic measurements from a pulp and paper mill. The measured traffic is further analyzed, which reveals representative traffic characteristics in the process automation. Finally, the key challenges and future directions towards a system architecture for factories of the future are presented.

Wireless technologies have been increasingly applied in industrial automation systems due to flexible installation, mobility, and cost reduction. Unlike traditional wireless sensor networks (WSNs), industrial wireless sensor networks (IWSNs), when expanding from wireless monitoring to wireless control, have more stringent requirements on reliability, real-time performance, and robustness in a number of industrial applications. Successive transmission failures or deadline misses in these applications may severely degrade the control quality and result in serious economic losses and safety problems. Therefore, when deploying IWSNs in harsh industrial environments, to achieve reliable and deterministic end-to-end transmissions is critically important. In this paper, we explain the primary challenges of designing appropriate routing protocols and present a reliable real-time flooding-based routing protocol for IWSNs (REALFLOW). Instead of traditional routing tables, related node lists are generated in a simple distributed manner, serving for packet forwarding. A controlled flooding mechanism is applied to improve both reliability and real-time performance. A seamless transition in the event of topology change can be achieved by REALFLOW. Performance evaluations via simulations verify that significant improvements of reliability, real-time performance, and network recovery time can be achieved by REALFLOW, compared with traditional routing protocols.

In this work we propose an Adaptive Forward Error Correction (AFEC) algorithm for best effort Wireless Sensor Networks. The switching model is described in terms of a finite-state Markov model and it is based on the channel behavior, observed via Packet Delivery Ratio in the recent past. We compare the performance of AFEC with static FEC, as well as uncoded transmissions. The results demonstrate a gain in PDR achieved by introducing FEC coding in uncoded IEEE 802.15.4 transmissions, as well as the advantages over static FEC schemes, namely increased throughput and reduced energy consumption. The proposed solution is IEEE 802.15.4-compliant and requires no additional feedback channels.

In this paper, we consider a wireless energy harvesting network consisting of one hybrid access point (HAP) having multiple antennas, and multiple sensor nodes each equipped with a single antenna. In contrast to conventional uplink wireless networks, the sensor nodes in the considered network have no embedded energy supply. They need to recharge the energy from the wireless signals broadcasted by the HAP in order to communicate. Based on the point-to-point and multipoints-to-point model, we propose two medium access control protocols, namely harvesting at the header of timeslot (HHT) and harvesting at the dedicated timeslot (HDT), in which the sensor nodes harvest energy from the HAP in the downlink, and then transform its stored packet into bit streams to send to the HAP in the uplink. Considering a deadline for each packet, the cumulative distribution functions of packet transmission time of the proposed protocols are derived for the selection combining and maximal ratio combining (MRC) techniques at the HAP. Subsequently, analytical expressions for the packet timeout probability and system reliability are obtained to analyze the performance of proposed protocols. Analytical results are validated by numerical simulations. The impacts of the system parameters, such as energy harvesting efficiency coefficient, sensor positions, transmit signal-to-noise ratio, and the length of energy harvesting time on the packet timeout probability and the system reliability are extensively investigated. Our results show that the performance of the HDT protocol outperforms the one using the HHT protocol, and the HDT protocol with the MRC technique has the best performance and it can be a potential solution to enhance the reliability for wireless sensor networks.

Clock synchronization is a core asset to protect when securing cyber-physical systems with a time-triggered architecture. One of the most challenging attacks to protect against is a delay attack, where an adversary delays one of the synchronization messages, making node offset calculations incorrect for keeping clocks synchronized. One way to detect a breach of clock synchronization is by monitoring the offsets calculated in a node according to the clock synchronization algorithm. The analysis in this work assumes that the distributed nodes need to share the same notion of time and for this reason, uses the IEEE 1588 standard. Using this approach, a monitor needs to make a decision about if and when a node is under attack, in which case rules and methods for decision making should be put in place. There are many aspects to consider when setting thresholds for the monitored values in order to make such a decision. In this work we conduct an analysis of monitor indicators and an investigation of their applicability. Further, we identify dependencies within the proposed monitoring approach and conduct a sensitivity analysis of the parameters needed to make a decision about a system being under attack. The analysis outcomes allow to identify important parameters to consider while thresholding indicators and enables a greater generality in their applicability.