Low-power wireless Internet of Things (IoT) devices employ Time Slotted Channel Hopping (TSCH) Medium Access Control to achieve predictable timing behaviour. TSCH aims at collision-free scheduling by exploiting diversity over time (slots) and frequency (channels). However, existing works on performance and worst-case analysis are based on deterministic models, which lead to rather pessimistic non-realistic results, i.e. tools for probabilistic performance analysis of TSCH schedulers are still lacking. In this context, we devised a Stochastic Network Calculus model that enables to calculate end-to-end delays for specific traffic flows and (deadline) violation probability, building on Moment Generating Functions. We instantiate this SNC model and provide bounds for three widely used TSCH schedulers, namely Minimal Scheduling Function, Orchestra, and a custom collision-free scheduler, with different parameters such as radio duty-cycle, radio link quality, and traffic arrival rate. We demonstrate that our proposed model closely follows the simulation results, under different network scenarios.

Applications of the Internet of Things (IoT), particularly within Industrial IoT, impose stricter reliability and efficiency requirements on low-power wireless technologies. This has driven the creation of new medium access protocols, such as Time Slotted Channel Hopping (TSCH). Recently, autonomous schedulers, which manage wireless links without node negotiation, are gaining popularity due to their lightweight and reliable operation. However, challenges arise with node mobility and dynamic traffic, as current schedulers use a static allocation method. To overcome this gap, we propose Forte, a hybrid scheduler that combines autonomous scheduling for basic connectivity with a centralized on-demand scheduler that allocates extra timeslots and frequency channels so that nodes adapt to the dynamic requirements. The centralized module formulates a Lyapunov optimization to guarantee queue stability while minimizing negotiation overhead and nodes’ duty-cycles. Forte outperforms the state-of-the-art by reducing packet end-to-end delay and increasing packet delivery ratio, all with minimal duty-cycle increase.

Future mines are expected to be operated by increasingly autonomous construction equipment, requiring dependable intercommunication between control centers, human operators, and construction machines such as excavators, drill rigs, and scrapers. Achieving stable, reliable and timely communications in such harsh and ever-changing environments is quite challenging. However, the changes in the three-dimensional (3D) topography of the mine are mostly predictable and scheduled through mine planning methods, which consequently can be used for radio communications network planning, namely to dimension, orientate and locate Base Station (BS) antennas in the mine field. In this context, we consider BSs to exist in the form of fixed cells or Cell on Wheel (CoW). The former is deployed in fixed locations throughout a long-term mine operation, while the latter is expected to be moved based on the changes in the topology of the terrain. We present an optimization framework that builds on an evolutionary algorithm to plan private 5G networks based on a given mine plan, featuring both fixed and movable base stations. We assess how the changing terrain affects the wireless coverage on the mine’s surface and demonstrate that, in certain scenarios, CoWs improve the average Signal-to-Interference & Noise Ratio (SINR) by 1 to 10 dB.

Under the vision of industry 4.0, industrial networks are expected to accommodate a large amount of aggregated traffic of both operation and information technologies to enable the integration of innovative services and new applications. In this respect, guaranteeing the uninterrupted operation of the installed systems is an indisputable condition for network management. Network measurement and performance monitoring of the underlying communication states can provide invaluable insight for safeguarding the system performance by estimating required and available resources for flexible integration without risking network interruption or degrading network performance. In this work, we propose a data-driven in-band telemetry method to monitor the aggregated traffic of the network at the switch level. The method learns and models the communication states by local network-level measurement of communication intensity. The approximated model parameters provide information for network management for prognostic purposes and congestion avoidance resource planning when integrating new applications. Applying the method also addresses the consequence of telemetry data overhead on QoS since the transmission of telemetry packets can be done based on the current state of the network. The monitoring at the switch level is a step towards the Network-AI for future industrial networks.

Industrial real-time software is commonly evaluated on real embedded systems, while simulators are less used, since the abstraction level and purpose vary with for example, different programming languages and run-time contexts. This paper extends, applies, and evaluates previous work on a flexible task design that improve code reuse between discrete event simulators and embedded real-time systems. The paper focuses on two parts: (i) The performance cost of the proposed design in practice, by comparing the flexible task design with a traditional threaded approach. (ii) The potential of an alternative way to support legacy code in combination with discrete event simulation. The experiments indicate an almost negligible performance cost with respect to the real-time behavior, i.e., latency and jitter, while enabling improved code reuse between discrete event simulation and industrial embedded real-time systems.

Most evaluations of industrial real-time software are conducted on real embedded systems. The use of simulators that provides easily reproducible evaluations is often limited, due to different levels of abstraction, e.g., programming languages and run-time contexts. This paper extends previous work on a flexible task design, enabling tasks to be agnostic to run-time context, with evaluations conducted on bare-metal and real-time operating systems. Based on the same design and experiments we extend the proof-of-concept implementation in a discrete event simulation context, executing on a Windows based simulation host. Our experiments show that the flexible task design can be driven in a simulation run-time context, and still support typical industrial constructs. The result indicates that improved code reuse between discrete event simulators and industrial embedded systems is feasible.

Heterogeneous networks (hetnets) is an interconnection of distinctive networking paradigms to enable wider reachability and greater collaborations. In large Internet-of-Things (IoT) applications, many wireless networks are spatially co-located and intertwined forming hetnets; for instance, health monitoring devices utilising ZigBee or IEEE 802.15.4 co-exist in 2.4 GHz spectrum alongside Wi-Fi devices. Interoperability or non-obtrusive operations are required among the disjoint domains to achieve operational efficiency in overall IoT ecosystem. Specifically, network interoperability in hetnets assure desired reachability, resource orchestration and network quality. In this work, we have modelled and implemented a simulation environment for hetnets to support different schemes of network interoperability under distributed and centralised management of network. The implementation has been evaluated for network scalability and reliability to replicate large IoT hetnets. By evaluating against increasing number of nodes in the hetnet, the mean latency under distributed management is improved by 100-fold with the centralised management. Similar observations could also be made for throughput and packet loss rate.

Industrial control systems have strict requirements for time-sensitive applications and clock synchronization services. Performance of such applications is adversely impacted by packet delays and jitters. The impact is especially critical in process industries due to harsh environmental conditions. In this paper, we analyze delays and jitters to assess the performance of time-sensitive applications. To this end, we captured and analyzed round trip delay data retrieved from a paper factory. Analysis shows that a sub-millisecond level average delays and the jitters derived from the observed data are sufficient to meet the minimum 10ms update frequency required for most critical control applications. Moreover, the filtered delay variations at the end devices are less than the recommended 150us, which guarantees an adequate time synchronization accuracy in the factory network. Besides, this analysis can provide significant insights into performance bottlenecks for factory applications.

The run-time context in industrial embedded systems varies from bare-metal microcontrollers, to multicore-processors running real-time operating systems. Due to the longevity of industrial systems, reusability and evolvability are often considered crucial quality attributes. This paper presents a new flexible task design that enables tasks to be agnostic to run-time context. Evaluations of the design were made by conducting experiments using a proof of concept implementation of the proposed design. The experiments were based on typical industrial constructs, such as periodic tasks, and event signaling from interrupts. Findings from the experiments show that tasks can be more agnostic to run-time context and still deliver functionality normally used within industry. The results indicate that it is feasible to improve reusability and evolvability between different run-time contexts, and in addition, support hybrid configurations that can reduce resource usage, since e.g. a thread can be easily shared among several tasks.

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.

Mobile text messages (SMS) are sometimes used for authentication, which requires short and reliable delivery times. The observed round-trip times when sending an SMS message provide valuable information on the quality of the connection. In this industry paper, we propose a method for detecting round-trip time anomalies, where the exact distribution is unknown, the variance is several orders of magnitude, and there are lots of shorter spikes that should be ignored. In particular, we show that using an adaption of Double Seasonal Exponential Smoothing to reduce the content dependent variations, followed by the Remedian to find short-term and long-term medians, successfully identifies larger groups of outliers. As training data for our method we use log files from a live SMS gateway. In order to verify the effectiveness of our approach, we utilize simulated data. Our contributions are a description on how to isolate content dependent variations, and the sequence of steps to find significant anomalies in big data.

Trends like the Cloud, Internet of Things and 5G are pushing for an increase in connectivity, but, introducing a new type of network in an industrial distributed control system is a big investment with high risks. Time to market with sufficient quality is crucial. However, when getting through the Research and Development (R&D) phases, a lot of time is spent on isolated activates, e.g., simulations, collecting requirements, design, coding, debugging, creating testbeds, and performing various tests. Therefore, there is a need to improve efficiency when moving between the R&D phases. For verification and validation of communication software, the most common network evaluation method in industry are real testbeds, mostly since a testbed can be very similar to the deployed system. Testbeds are, however, hard to debug and costly to maintain. Other network evaluation methods like simulators, have some strengths that testbeds are lacking, like repeatability, control over the network, and lower cost. However, code from simulators can seldom be reused, especially in industrial time-sensitive target systems, due to different abstraction levels, run-time behavior and system timing. This paper presents findings from a case study that targets improved efficiency, getting from research theories, to deployed devices in a homogeneous Industrial Wireless Sensor and Actuator Network (IWSAN). We propose a small subset of network simulators features which eases changeability, reuse, and debugging of communication software. The selected simulator features are evaluated with a proof of concept implementation that is customized to a research platform. The findings indicate improved efficiency when moving back and forth between activities in different R&D phases.

Over the past decade, fast technological and industrial advances have been happening in the area of autonomous Systems of Systems (SoS). A SoS is built upon integration of several systems, where the complexity of such a structure is exponentially higher which brings challenges to its analysis. However, it also has provided a large set of new opportunities in domains such as air traffic control, defense, construction industry, etc. It is expected that fully autonomous and cooperating systems will increase the production efficiency, while decreasing (potentially completely replacing) the human effort in harmful environments. In order to enable this, we need to make sure that critical properties of SoS, such as safety and security are guaranteed. We believe that it is not sufficient anymore to analyze and guarantee these properties independently, but we have to be able to address safety and security in a joint effort. Communications in systems with any type of real-time requirements, where data validity is based on its freshness, rely on clock synchronization (CSyn) allowing its subsystems to cooperate and work coherently. Considering reliable and predictable communication as one of the main assets contributing to correct functionality of such systems, protecting CSyn from malicious adversaries should be one of the highest priority efforts in SoS. In this paper we show how CSyn breaches can influence security, and ultimately safety of complex and autonomous SoS, further we identify a missing piece to consider in safety assurance, namely assurance with respect to reliable communications between systems within the SoS. We demonstrate how an outcome of a security analysis can be used as input for the overall safety analysis and we use an autonomous quarry as an example application to illustrate our findings.

Supporting real-time applications over wireless networks is challenging for several reasons. The medium access control (MAC) layer has a key role in enabling real-time guarantees by providing bounded access time to the transmission medium. Unfortunately, even when timely access is granted, transmissions can still be compromised, specially in the wireless domain, due to the unreliable transmission medium. A common way to increase the reliability of a communication system is to apply redundancy in the form of time diversity, i.e., transmitting several copies of the same message at different points in time. In this paper we propose a wireless MAC protocol capable of handling traffic with different levels of criticality and where transmissions and retransmissions are tailored to deadlines, so that the reliability of the communication system is increased and real- time guarantees can be provided. We focus on the traffic scheduling problem, and extend an already existing solution, Time-Triggered Ethernet, suitable for real-time traffic over wired multi- hop networks. The extension enables transmission of heterogeneous traffic over hybrid wired- wireless networks, and provides timely retransmissions in the wireless segment, such that the real-time guarantees are met. Further, we are able to schedule traffic to better cope with interference patterns of different duration, frequency and level of persistence. The results show that the MAC protocol can be successfully applied to combat different kinds of interference while meeting real-time deadlines.

Industrial wireless sensor and actuator networks (IWSANs) offer significant advantages to industrial automation. However, high-reliability demands and hard communication deadlines pose challenges to its practical applications. To achieve this goal, flooding is considered as a promising approach due to multipath diversity and simplicity. In this paper, an enhanced version of REALFLOW, a flooding-based routing protocol for IWSANs is presented. Compared to the original REALFLOW, network management and network stability are improved. REALFLOW is compared with four other flooding protocols via simulations. The simulation results show that REALFLOW has better performance in terms of reliability and consecutive transmission errors when considering deadlines. Compared with normal flooding, REALFLOW achieves comparable reliability performance with decreased redundancy. Measurements from a prototype implementation conducted in an industrial manufacturing workshop reveal that high-reliability and low-application failure rates can be achieved, giving more confidence in providing reliable wireless sensing and actuating for industrial automation.

The fast development of sensing devices and radios enables more powerful and flexible remote health monitoring systems. Considering the future vision of the Internet of Things (IoT), many requirements and challenges rise to the design and implementation of such systems. Bridging the gap between sensor nodes on the human body and the Internet becomes a challenging task in terms of reliable communications. Additionally, the systems will not only have to provide functionality, but also be highly secure. In this paper, we provide a survey on existing communication protocols and security issues related to pervasive health monitoring, describing their limitations, challenges, and possible solutions. We propose a generic protocol stack design as a first step toward handling interoperability in heterogeneous low-power wireless body area networks.

A growing concern of cyber threats towards industrial plants has prompted industrial practitioners to focus on secure communication solutions which can protect their systems from vulnerabilities and as well as their brand image. The security concerns and the solutions for industrial communication networks have become well-discussed topics in research communities. Despite a huge research effort in the area of industrial communication network security, there are several issues that need to be addressed properly such that a unified security solution can be adopted in the industrial domain. In this article, we aim to outline the research direction for industrial communication security. Though security is considered as an on-going process, the major issues that still need to be addressed are trust management for heterogeneous networks, managing network performance with security requirements, usable security and key management.

Congestion control is a challenging issue in wireless sensor networks with limited channel bandwidth. Thus, many protocols have been designed to provide a distributed traffic control during packet forwarding. However, all these approaches are applied to single-hop communication networks, ignoring the multi-hop restrictions. In this work, we take advantage of software defined networking paradigm by devising a controller node in such a way that it collects all the necessary information from wireless sensor network nodes. Thus, based on hop count and local traffic information, controller decides for possible flow path changes to evenly distribute the traffic. The evaluations revealed that the SDN-TAP outperforms conventional routing protocols by reducing packet loss rate up to 46%.

The communication in-between embedded systems present in cars and planes, requires real-time networks. Up to now, fieldbus technologies like PROFIBUS and CAN have covered the demand for predictable communications in embedded systems. However, these fieldbuses do not suit some of the emerging application domains, that need more flexibility, support for dynamic traffic flows, different traffic classes, high throughput, and the inclusion of wireless capabilities. To this end, we propose several different medium access control (MAC) schemes with support for traffic with diverse time and safety requirements. We have calculated the worst case channel access delay for each proposal, and also simulated them in OMNeT++ to analyse and compare their performance in terms of average access delay and packet collisions as a function of different protocol settings and traffic patterns e.g., the channel load, data traffic emerging from one sender only versus evenly distributed between all senders. Our results indicate that the more that is known about the data traffic, the better performance can be achieved by selecting an appropriate MAC protocol. Conversely, when nothing is known, one MAC protocol emerges as the best trade-off.

A trend in the industrial domain is that the networks are growing and becoming more complex, this is further accelerated by the digitalization trend. In order to address this, there is a need to improve the efficiency when moving between the R&D phases. For example, integrate innovative research findings into industrial systems, shorten time to market, improve product quality and reduce the number of issues. Despite a huge research effort on network simulators and emulators there are still some issues that needs to be addressed. This paper presents challenges that needs to be resolved, in order for the industry to adopt and benefit from using network simulators and emulators. The major challenges streamlining the workflow in and between the different R&D phases while preserving the real-time aspects in the entire industrial distributed control system.

A key aspect of realizing the future smart grid communication solution is a balanced approach between the network performance and the network security during the network deployment. A high security communication flow path is not useful when the network path cannot support capacity and reachability requirements. The deployment phase in communication network can facilitate an optimal network path by focusing on both the network performance and the network security at the same time. In this paper, we describe a use case of smart grid application where security, network capacity and reachability needs to be optimal for successful network operation. We explain our proposed balancing approach of the network performance and the network security which can be useful for the optimal smart grid secure system design.

The interest in wireless communication systems for industrial applications has grown significantly over the last years. More flexible, easier to install and maintain, wireless networks present a promising alternative to the currently used wired systems. However, reliability and timeliness requirements at present met by wired networks also need to be fulfilled by wireless solutions. Packet errors introduced when packets travel through wireless channels imply a significant challenge to fulfill these requirements. Relaying has been recognized to improve the reliability in industrial wireless networks without causing additional delay. Furthermore, the recent results have shown that relaying combined with packet aggregation significantly outperforms simple relaying. However, it is not always cost efficient to introduce additional relay nodes into an industrial network and hence, in this paper, we propose using a combination of relaying and packet aggregation at the source nodes. The results show that when relaying and aggregation are used at the source nodes, the transmission schedule plays a crucial role. A schedule adapting to the varying channel conditions improves performance substantially. By carefully choosing which packet to aggregate, even further improvements can be achieved.

The security in industrial automation domain using cryptography mechanisms is being discussed in both industry and academia. An efficient key management system is required to support cryptography for both symmetric key and public/private key encryption. The key management should ensure that the device is verified before distributing the initial key parameters to devices. The software/firmware used in the device comes from manufacturers, therefore the initial authenticity of the device can be easily verified with the help of manufacturers. Mobile telecommunication is an industrial segment where wireless devices are being used for a long time and the security of the wireless device management has been considered through a standard driven approach. Therefore, it is interesting to analyse the security authentication mechanisms used in mobile communication, specified in Long-Term-Evolution (LTE) standard. This paper analyses the initial device authentication using public key infrastructure in LTE standard, and discusses if, where and how the studied solutions can be tailored for device authenticity verification in industrial plant automation systems.

This paper deals with a way to probabilistically guarantee reliable packet delivery in WirelessHART based networks suitable for industrial control systems. We propose a new scheduling scheme, called Iterative Probabilistic Scheduling with Adaptive Relaying (IPS-AR), which consists of a static part (IPS) and a dynamic part (AR). IPS takes into account the channel characteristics and exploits relaying to achieve a minimum reliability threshold as requested by the supported industrial application. In the AR part, each relay node decides the packet to be sent based on online assessment of both the number of consecutive errors experienced by previous packets belonging to the same flow, as well as the number of copies of the packet currently available at the other relay nodes. This enables IPS-AR to achieve the desired reliability level while using the available re-sources in terms of time and bandwidth more efficiently.

In industrial plants, there is a mix of devices with different security features and capabilities. If there is a mix of devices with various degree of security levels, then this will create independent islands in a network with similar levels of security features. However, the industrial plant is interconnected for the purpose of reducing cost of monitoring with a centralized control center. Therefore, the different islands also need to communicate with each other to improve the asset management efficiency in a plant. In this work we aim to focus on the trustworthiness assessment of devices in industrial plant networks in term of node value. We study the behavior of industrial plant networks when devices with various degrees of security features communicate. We aim to identify network properties which influence the overall network behavior. From the study, we have found that the communication path, the order of different communication paths and the number of specific types of nodes affect the final trustworthiness of devices in the network.

An important aspect of any communication technology is its medium access method, being responsible for sharing the medium among users. For delay-sensitive applications, such as industrial control systems, timely and reliable channel access is of essence. Hence, existing protocols like HART and TTEthernet use a time-triggered medium access approach. However, as the nature of industrial control systems change and evolve, there is a growing need to provide wireless access and support data traffic with mixed requirements. While technologies like WirelessHART can offer timely and reliable access to the wireless medium, only one type of data traffic is usually supported. In this paper, we therefore propose and evaluate three different medium access methods for wireless communications, all capable of supporting three different data traffic classes: time-triggered, rate-constrained and best-effort traffic. In particular, different options on how to handle best-effort traffic, using scheduled time-slots or contention, are evaluated, showing for all the proposals different drawbacks and benefits depending on additional requirements on e.g., hardware, protocol overhead and resistance to interference.

Industrial networks have a mix of devices with different security properties. If a mix of devices with various degrees of security features and capabilities communicate, the overall network dynamics with respect to device trust and security of message exchange will be complex. Therefore, there is a need to understand the trust and risk probabilities of devices in a heterogeneous network. This is required for heterogeneous network where the network configuration has to be made based on how trustworthy they are. In this work we focus on assessing security risks for devices and message exchanges. We define the term assurance value to denote the resilience of a device to security attacks. We study the behavior of a communication network when devices with various degrees of security features exchange messages. We aim to identify the network security properties based on the network architecture. From the study, we propose a model to estimate and predict network security properties in a heterogeneous communication network.

Wireless networks present a promising alternative to the currently used wired systems as they are more flexible, easier to install and maintain. However, requirements on reliability and timeliness which at present are met by wired networks, also need be fulfilled by wireless solutions. Relaying and packet aggregation have been recognised as viable tools to do this. However, introducing additional relay nodes into an industrial network is costly. Hence, in this paper we propose to use a combination of relaying and packet aggregation performed by the source nodes themselves. The results show that our proposal improves performance considerably, but also that the transmission schedule plays a crucial role. A schedule adapting to the varying channel conditions, improves the performance substantially. By carefully choosing which packet to aggregate, even further improvements can be achieved.

TTEthernet is a communication platform which builds on Ethernet, but extends it to include fault-tolerance and real-time mechanisms. The existing TTEthernet technology is developed for wired networks. A natural step for improving and extending the current application field is the introduction of a mixed wired and wireless network. However, this step requires research both about possible adaptation of existing systems as well as implementation of new technologies. A central research question is the security aspects of real-time sensor networks using wired and wireless technologies based on TTEthernet. In this paper, we identify and classify the most important aspects to consider in order to provide secure communications in such safety-critical industrial applications and propose a potential solution to address identified issues.

Providing reliable and timely communication in wireless industrial networks is crucial. Previous research has shown that relaying can aid in achieving this goal. We consider the case when relay resources are sparse such that each relay needs to aid e.g., three different sensor nodes and propose to combine relaying with Luby codes. We let the relay node construct a Luby coded packet using the three source packets as input. The destination can then use the Luby coded packet to recover an erroneous or lost source packet regardless of which source that packet belonged to. The performance evaluation shows that our proposed scheme significantly increases the number of correctly received packets before the corresponding deadlines, or alternatively that high reliability can be maintained even if fewer time slots are allocated for retransmissions, thus lowering the delay.

Industrial device commissioning along with the initial distribution of keying material is an important step for the security of industrial plants. An efficient key management system is required in cryptography for both symmetric key or public/private key encryption. Most of the key management system use either pre-installed shared keys or install keys using out-of-band channels. In addition to that, the sensor devices both wired and wireless need to be verified whether it is connected to the correct physical entity since these devices are linked with the physical world. Therefore in industrial plants there is a requirement to automate the trust bootstrapping process, where the devices from upper level in communication network will be aware that the communication device from below level is trusted. In this work, we present a workflow that uses the existing trust mechanism on employees to enable the initial bootstrap of trust in the devices, and also optionally support the commissioning engineer to download the required configuration data in the device as well. Thus, this approach presents a unique solution to the initial trust distribution problem reusing the existing features and facilities in industrial plants.

Applying Industrial Wireless Sensor and Actuator Networks (IWSANs) in the industrial automation is a growing trend due to flexibility, mobility and low cost. According to the current standards, such asWirelessHART and ISA100.11a, multi-channel TDMA transmission is included for reliable and deterministic communication. In this paper, we clarify the dependence of TDMA scheduling for sensors and actuators and point out the low correlation between the scheduling delay and the overall quality of control, and focus on reducing jitter in scheduling for improving quality of control and system stability. We propose a scheduling algorithm, aiming for lowing jitter and compare it with two traditional real-time scheduling schemes. Our simulation results exhibit significantly lower jitters by applying our scheduling policy than those two traditional scheduling schemes.

The security of industrial plants has gained a lot of importance since the last decade. The reason is that the different components from different network layers of automation systems have become inter-connected to support fast and cost-effective decisions at the management level. This inter-connectivity has posed many security challenges in this industrial segment. To achieve effective security mechanisms in industrial plants, there is a need to learn from other existing domains, matured in terms of security, whether existing matured security solutions can be reused in the industrial automation domain. The financial sector is a segment where security has been carefully managed since a long time, as security is very important for that sector. Therefore it would be beneficial to evaluate the security mechanisms present in financial card readers which are involved in financial transactions because these card readers have many similar characteristics with industrial process control devices. In this paper, the security requirements for both the field devices of industrial plants and card reader terminals of the financial sector have been evaluated to understand the security gap so that we can identify the areas where the security needs of industrial plants must be improved and where some of the existing security features of card reader terminals can be reused in field devices of industrial plants.

In many new distributed systems paradigms such a cloud computing, Internet of Things (IoT), electronic banking, etc. the security of the host platforms is very critical which is managed by the platform owner. The platform administrators use security automation techniques such as those provided by Security Content Automation Protocol (SCAP) standards to ensure that the outsourced platforms are set up correctly and follow the security recommendations (governmental or industry). However, the remote platform users still have to trust the platform administrators. The third party security audits, used to shift the required user trust from the platform owner to a trusted entity, are scheduled and are not very frequent to deal with the daily reported vulnerabilities which can be exploited by the attackers. In this paper we propose a remote platform evaluation mechanism which can be used by the remote platform users themselves, or by the auditors to perform frequent platform security audits for the platform users. We analyze the existing SCAP and trusted computing (TCG) standards for our solution, identify their shortcomings, and suggest ways to integrate them. Our proposed platform security evaluation framework uses the synergy of TCG and SCAP to address the limitations of each technology when used separately.

High reliability and real-time performance are main research challenges in Industrial Wireless Sensor Networks (IWSNs). Existing routing protocols applied in IWSNs are either overcomplicated or fail to fulfill the stringent requirements. In this paper, we propose a reliable and flexible Received Signal Strength-based routing scheme. Our proposed solution can achieve a seamless transition in the event of topology change and can be applied in different industrial environments. The simulation results show that our solution outperforms conventional routing protocols in both reliability and latency. Furthermore, the result also proves that the changes of the network topology have no impact on data transmissions of other nodes by our scheme, whereas conventional routing protocols are shown to fail to recover the network in a short time. Finally, due to dynamic weighting mechanism, the proposed scheme is verified to achieve significantly higher reliability in scenarios with obstacles and avoid installation troubles, compared to location-based flooding scheme. Thus, our proposed scheme is considered to be more suitable for IWSNs than other routing protocols.

In this paper we address the issues of timeliness and transmission reliability of existing industrial communication standards. We combine a Forward Error Correction coding scheme on the Medium Access Control layer with a lightweight routing protocol to form an IEEE 802.15.4-conformable solution, which can be implemented into already existing hardware without violating the standard. After laying the theoretical foundations, we conduct a performance evaluation of the proposed solution. The results show a substantial gain in reliability and reduced latency, compared to the uncoded transmissions, as well as common Wireless Sensor Network routing protocols.

In this paper we consider the security and trust implications of virtual machine (VM) migration from one cloud platform to the other in an Infrastructure-as-a-Service (IaaS) cloud service model. We show how to extend and complement previous Trusted Computing techniques for secure VM launch to also cover the VM migration case. In particular, we propose a Trust_Token based VM migration protocol which guarantees that the user VM can only be migrated to a trustworthy cloud platform. Different from previous schemes, our solution is not dependent on an active (on-line) trusted third party. We show how our proposed mechanisms fulfill major security and trust requirements for secure VM migration in cloud environments.

The research within this paper identifies three main categories of cross-cultural communication challenges within international transfer of aircraft production. The first category is organizational structure, hierarchy and delegation of responsibility the second category is consensus behavior and avoidance of conflicts and the third category is individual motivation factors. Furthermore, the paper discusses the need for specific types of cross-cultural training that can be one solution for reducing the problems and difficulties that cultural challenges may induce. The case study indicates that it is important for Aeronautics, a Swedish enterprise, to apply organized cross-cultural training in combination with technical training. To secure the presence of cross-cultural training, suitable types of cultural training could be included in the working process/routine for how to conduct a production transfer.

Contrary to the various theoretic publications on safety-critical communication over wireless, this paper will show the actual performance of safety-critical communication in a real plant with all its environmental influences. We used PROFIsafe as a functional safety profile on top of the WirelessHART protocol. Separately these technologies are widely used in industry for safety and wireless communication respectively, but it has never been shown that the combination of them is feasible for safety-critical communication. The main focus of this work is to measure and analyze the round-trip time and the bit error rate of the safety-critical communication in order to identify whether the certification requirements of PROFIsafe holds. We will show that it is technically feasible to run safety-critical data over wireless links. However, long round trip times and high noise in the channel at certain locations in the plant are unacceptable with respect to certification and need further investigations.

Two major trends can be recognized in industrial automation. One of them is that Ethernet is replacing traditional fieldbus networks continuously, because it combines flexibility, reliability, and introduces fast data rates, which allow beside others quality of services. This is pushed even further when field devices use wireless communication to connect to the control system. Beside that another trend is seen in functional safety due to rising customer demands and evolving regulations in industry. That leads necessarily to a consolidation of both technologies, where safety must be guaranteed in the same manner over wireless channels as it is handled over Ethernet. This paper addresses safety issues emerging when PROFIsafe, as one of various safety protocols on the market, is used on top of a black channel layer, that is comprized of non-safe protocols including WirelessHART.

Internet traffic volumes continue to grow at a great rate, now pushed by video and TV distribution in the networks. This brings up the need for traffic engineering mechanisms to better control the traffic. The objective of traffic engineering is to avoid congestion in the network and make good use o

In this paper we show that it is possible to retrofit a security layer on top of PROFINET IO without changing the underlying transmission system or standards. By introducing security modules, end-to-end network security can be achieved and ensure authentication, integrity and confidentiality for real-time communication. The concept of security modules is a flexible framework and countermeasures can be changed, as security threats and exploits are changing over time. A proof-of-concept implementation shows that it is possible to implement security modules on existing products and secure them against, for example, man-in-the-middle attacks.

A major issue in wireless sensor networks is to prolong network lifetime by efficient energy management. In this paper we present an initial study of maximum lifetime routing in sparse sensor networks. We have studied simulations of how different heuristic routing algorithms influence the energy consumption of individual sensor nodes, and thus the functional lifetime of a sparse sensor network. The functional lifetime of the sensor network can be either until the first node has run out of energy or until a certain threshold of nodes has demised. We have also compared the maximum lifetime of the heuristic algorithms to the maximum lifetime of an optimal routing solution. Our simulations with nonaggregated data indicates that using one of the presented heuristic routing algorithms are not enough to find a near optimal routing. Our study is made in the AROS framework.

BART is a state-of-the-art active end-to-end bandwidth measurement method that estimates not only the available bandwidth but also the link capacity of the bottleneck link. It uses a Kalman filter to give estimates in real time during a measurement session. In this paper, we have studied the impact of 802.11 networks on the bandwidth estimates produced by BART. The Kalman filter used by BART is tunable, and one of the contributions of this paper is to show how the Kalman filter should be adjusted to improve real-time tracking and estimation accuracy when the bottleneck is an 802.11 link. Further, the paper contributes by discussing how to interpret the estimates produced by BART and similar bandwidth estimation tools relying on self-induced congestion when used in wireless scenarios. An analysis show that the BART estimates produced are correct - but corresponds to a fair share of the wireless link rather than to the unused capacity. However, the estimates do indicate how much bandwidth an application or device in the wireless network can expect when sending and/or receiving network traffic.

Testing in realistic environments is often overlooked in the early development of new technology. This paper describes a test to evaluate the whole chain from an accelerometer mounted on a motor to a sensor node sending wireless data to an access point. A pilot gives a great opportunity to get input from end-users (which could be very useful at the initial stages of a project), and provide potential contacts for next pilots. The goal of the pilot was to get a better understanding of the targeted environment and possible interference It may also lead to the discovery of issues not yet thought of issues important for the resulting design of the end product.

This paper presents a new method, BART (bandwidth available in real-time), for estimating the end-to-end available bandwidth over a network path. It estimates bandwidth quasi-continuously, in real-time. The method has also been implemented as a tool. It relies on self-induced congestion, and repeatedly samples the available bandwidth of the network path with sequences of probe packet pairs, sent at randomized rates. BART requires little computation in each iteration, is lightweight with respect to memory requirements, and adds only a small amount of probe traffic. The BART method uses Kalman filtering, which enables real-time estimation (a.k.a. tracking). It maintains a current estimate, which is incrementally improved with each new measurement of the inter-packet time separations in a sequence of probe packet pairs. The measurement model has a strong non-linearity, and would not at first sight be considered suitable for Kalman filtering, but we show how this non-linearity can be handled. BART may be tuned according to the specific needs of the measurement application, such as agility vs. stability of the estimate. We have tested an implementation of BART in a physical test network with carefully controlled cross traffic, with good accuracy and agreement. Test measurements have also been performed over the Internet. We compare the performance of BART with that of pathChirp, a state-of-the-art tool for measuring end-to-end available bandwidth in real-time

We study the packet dispersion phenomenon that a traffic flow experiences when it passes through a router. We show that when there are competing flows and the router schedules packets first-come-first-served (FCFS), the dispersion is not described well by the bottleneck spacing effect. We therefore introduce the term FCFS-spacing effect. We also show that for a router implementing weighted fair queuing, dispersion is due either to the bottleneck spacing effect or the FCFS spacing effect. The results from real measurements and simulations corroborate each other. Finally, we discuss the implications of FCFS packet dispersion on TCP's self-clocking mechanism.

Quickly transmitting large datasets in the context of distributed computing on wide area networks can be achieved by compressing data before transmission, However such an approach is not efficient when dealing with higher speed networks. Indeed, the time to compress a large file and to send it is greater than the time to send the uncompressed file. In this paper we explore and enhance an algorithm that allows us to overlap communications with compression and to automatically adapt the compression effort to currently available network and processor resources.

We present a network friendly bandwidth measurement method, TOPP, that is based on active probing and includes analysis by segmented regression. This method can estimate two complementing available bandwidth metrics in addition to the link bandwidth of the congested link. Contrary to traditional packet pair estimates of the bottleneck link bandwidth, our estimate is not limited by the rate at which we can inject probe packets into the network. We also show that our method is able to detect bottlenecks that are invisible to methods such as the C-probe. Further more, we describe scenarios where our analysis method is able to calculate bandwidth estimates for several congested hops based on a single end-to-end probe session.

We review previous work on the applicability and performance of integrated layer processing (ILP). ILP has been shown to clearly improve computer communication performance when integrating simple data manipulation functions, but the situation has been less clear for more complex functions and complete systems. We discuss complications when applying ILP to protocol stacks, the requirements of ILP on the communication subsystem, caching aspects, the importance of the processor registers, and a model for predicting the performance of data manipulation functions. We conclude that the main drawback of ILP is its limited applicability to complex data manipulation functions. The performance to expect from an ILP implementation also depends heavily on the protocol architecture and the host system architecture.

Two major performance bottlenecks in multiprocessor execution of protocols are contention for shared memory and for locks. Locks are used to protect shared messages and/or shared protocol state in a memory shared by competing processors. Mutual exclusion by locking can be costly, in terms of both lock contention and memory contention, if the parallel protocol code frequently accesses shared state and data. This paper presents a queueing network model for performance predictions of shared-memory multiprocessor protocol executions. Predictions from this model are compared to performance measurements from a multiprocessor implementation of two commonly used communication protocol stacks, transmission control protocol/Internet protocol (TCP/IP)/Ethernet and user datagram protocol/Internet protocol (UDP/IP)/Ethernet. These stacks are implemented on a parallelized version of the x-kernel protocol environment from the University of Arizona. A "processor-per-message" paradigm is used to partition the load among the processors. The measured speedups for the parallel implementations relative to the sequential ones are more than 11 times for UDP (using 20 processors) and three times for TCP (using five processors) on a sequent symmetry. We show that the model accurately captures the effects of lock and memory contention in our shared-memory multiprocessor and predicts the performance with a discrepancy of less than 10%.

We investigate how to exploit shared memory multiprocessors for parallel protocol processing. We present a multiprocessor implementation of the x-kernel protocol environment from the University of Arizona. A processor-per-message paradigm is used to partition the work over processors. Locks are used to protect shared protocol state and data. Mutual exclusion by locking can be costly if the parallel protocol code frequently accesses shared state and data. This paper addresses the effect of locking on performance.The x-kernel is implemented in user address space on a Sequent Symmetry. Performance results of UDP/IP and TCP/IP are given, and we compare them to performance predictions from simulations. The measured speedups for the parallel implementations relative to the sequential ones are more than 12 times for UDP and 3 times for TCP. These limits are set by locking and machine contention.