Dissertations / Theses on the topic 'Industrial wireless protocols'

Wireless Communication is the only solution for data transfer between mobile terminals to access the sensors and actuators in industrial environment Control Area Network (CAN) is desirable solution for many industrial applications since it meets the requirements of real-time transfer of messages between systems. In situations where the use of a cable is not feasible it is important and necessary to design wireless medium access control protocols for CAN to provide real-time communications. This thesis deals with modelling, simulation and performance analysis of wireless medium access control protocols for CAN. The main issue in this concept is to determine prioritisation of the messages in the wireless environment. In order to accomplish this, a Wireless Medium Access Control protocol called WMAC is first proposed for distributed environment. The prioritisation in the WMAC protocol is achieved by performing an operation of timing the interframe gap. In this method, every message within the network is assigned a unique time period before the transmission of the message. These individual time periods distinguish messages from each other and provides message priority. Second access method called Remote Frame Medium Access Control (RFMAC) protocol is proposed for centralised wireless environment. Since the central node organises the message traffic the prioritisation is accomplished automatically by the central node. Both protocols are evaluated by using simulation techniques. The third access method called Comb is designed by using an additional overhead which consist of binary sequence. The prioritisation in this access method is managed by the overhead. Additionally, the interconnection of wireless nodes is investigated. The results of the simulations and performance analysis show that the proposed protocols operating in the centralised and distributed environments are capable of supporting the prioritisation of the messages required for real-time industrial applications in a wireless environment.

[Truncated abstract] Developing wireless sensor network communication protocols for industrial environments is a challenging task. The wireless channel conditions in industrial environments are harsher as a result of multipath propagation of radio signals within an environment where the mechanics of the surrounding industrial activities often lead to severe small-scale fading effects. The design of network protocols to function in such an environment needs to provide a robust communication platform for the wireless sensor nodes, while optimizing the utilization of the limited node resources available. As existing general MAC protocols for wireless sensor networks do not work well under harsh channel conditions, we address this problem in this thesis by proposing a medium access control (MAC) protocol framework for wireless sensor networks in industrial environments. To describe the impact of an automated industrial site on small-scale fading effects in an industrial indoor wireless network, we use a site-specific ray-tracer for predicting signal propagation based on building blue prints to simulate the signal propagation paths through an industrial site with periodically moving objects. We found that in a fully automated industrial site, the periodic movements of objects with constant velocities result in an approximately periodic distribution of fading periods in the channel. Based on this finding, we propose a link state dependent TDMA-based MAC protocol for wireless sensor networks designed for automated industrial applications. ... This technique also conserves energy and maximizes packet integrity as the sensor nodes avoid performing network activities when the channel is sampled to be affected by fading. As a measure for fault-tolerance, we also propose a dynamic link reconstruction technique that allows sensor nodes to reconstruct new parent links when their present links are severely affected by fading. MAC protocols that adopt active buffering in fading-affected channels suffer bufferoverflow and latency issues as a result of the postponement of scheduled transmissions during periods when the channel is in a fade. Consequently, time-sensitive data packets that may contain critical information may miss their deadlines in a severely affected fading channel. Hence, we propose a general fading-aware data management (FADE) MAC protocol extension that uses buffer nodes to offload the memory buffer off sensor nodes in the network and prioritizes traffic based on a simple proposed priority scheme. The FADE extension provides a balance balance between minimum end-to-end latency for critical event reporting, high packet delivery guarantee, low energy consumption, and minimum buffer requirements on the sensor nodes. In summary, this thesis presents the design, implementation, and evaluation of all our proposed network protocols that are combined as a framework for wireless sensor networks in industrial environments.

Redes de sensores sem fio tem ganhado grande destaque em diferentes aplicações, tais como, domésticas, comercial e industrial, trazendo mais flexibilidade e mais conveniência em nossas vidas. Entretanto, seu desempenho é influenciado por diversos fatores como, por exemplo, características do ambiente de propagação das ondas de rádio e outras tecnologias de comunicação sem fio que podem coexistir em uma mesma área de cobertura. Os recursos utilizados nas comunicações sem fio são limitados e muitas vezes não exclusivos possibilitando interferências provenientes de diferentes tipos de fontes. O presente trabalho busca soluções para o uso mais eficiente dos recursos da rede de comunicação sem fio, são investigados e propostos métodos adaptativos para uma rede sem fio industrial, o protocolo WirelessHART, utilizando mecanismos dinâmicos de sensoriamento de espectro e seleção de canal entre os dispositivos da rede. É apresentado uma arquitetura de gerenciamento do espectro em conformidade com o protocolo, baseado em sensoriamento do espectro distribuído e no monitoramento do desempenho das comunicações. A arquitetura utilizada permite a classificação de um conjunto de canais específicos entre os pares de dispositivos durante a operação da rede de comunicação. O trabalho demonstra o desempenho dos mecanismos desenvolvidos para a detecção de interferências com redes do tipo IEEE 802.11.
Wireless sensor networks have been expanding rapidly in many applications for different areas such as residential, office and industrial. Wireless connections bring many advantages as installation feasibility, scalability, mobility and reduce infrastructure costs. However, wireless network performance is affected by many factors as, for example, environment characteristics and other wireless communication technologies at the same coverage area. The wireless communication resources are limited and many times shared, allowing interferences from different kind of electromagnetic sources. This work presents a solution for an efficient use of the wireless communication network resources, investigate and propose adaptive methods for an industrial wireless network, the WirelessHART protocol, using dynamic mechanisms of spectrum sensing and channel selection between the devices. A protocol spectrum management architecture based on distributed sensing and monitoring of communications performance is presented, in compliance with WirelessHART protocol, allowing the classification of a set of specific channels between peer devices during the communication network’s operation. Also, it is presented the channel selection performance for IEEE 802.11 interference.

When designing architectures and protocols for data traffic requiring real-time services, one of the major design goals is to guarantee that traffic deadlines can be met. However, many real-time applications also have additional requirements such as high throughput, high reliability, or energy efficiency. High-performance embedded systems communicating heterogeneous traffic with high bandwidth and strict timing requirements are in need of more efficient communication solutions, while wireless industrial applications, communicating control data, require support of reliability and guarantees of real-time predictability at the same time. To meet the requirements of high-performance embedded systems, this thesis work proposes two multi-wavelength high-speed passive optical networks. To enable reliable wireless industrial communications, a framework in­corporating carefully scheduled retransmissions is developed. All solutions are based on a single-hop star topology, predictable Medium Access Control algorithms and Earliest Deadline First scheduling, centrally controlled by a master node. Further, real-time schedulability analysis is used as admission control policy to provide delay guarantees for hard real-time traffic. For high-performance embedded systems an optical star network with an Arrayed Waveguide Grating placed in the centre is suggested. The design combines spatial wavelength re­use with fixed-tuned and tuneable transceivers in the end nodes, enabling simultaneous transmis­sion of both control and data traffic. This, in turn, permits efficient support of heterogeneous traf­fic with both hard and soft real-time constraints. By analyzing traffic dependencies in this mul­tichannel network, and adapting the real-time schedulability analysis to incorporate these traffic dependencies, a considerable increase of the possible guaranteed throughput for hard real-time traffic can be obtained. Most industrial applications require using existing standards such as IEEE 802.11 or IEEE 802.15.4 for interoperability and cost efficiency. However, these standards do not provide predict­able channel access, and thus real-time guarantees cannot be given. A framework is therefore de­veloped, combining transport layer retransmissions with real-time analysis admission control, which has been adapted to consider retransmissions. It can be placed on top of many underlying communication technologies, exemplified in our work by the two aforementioned wireless stan­dards. To enable a higher data rate than pure IEEE 802.15.4, but still maintaining its energy saving properties, two multichannel network architectures based on IEEE 802.15.4 and encompassing the framework are designed. The proposed architectures are evaluated in terms of reliability, utiliza­tion, delay, complexity, scalability and energy efficiency and it is concluded that performance is enhanced through redundancy in the time and frequency domains.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-08-24T20:51:57Z No. of bitstreams: 1 RUAN DELGADO GOMES – TESE (PPGEEI) 2017.pdf: 20190080 bytes, checksum: c170f5c01c9d6fd739d197414aee12e7 (MD5)
Made available in DSpace on 2018-08-24T20:51:57Z (GMT). No. of bitstreams: 1 RUAN DELGADO GOMES – TESE (PPGEEI) 2017.pdf: 20190080 bytes, checksum: c170f5c01c9d6fd739d197414aee12e7 (MD5) Previous issue date: 2017-06-14
O uso de Redes de Sensores sem Fio Industriais (RSSFIs) para implementar aplicações de monitoramento ou controle apresenta vantagens em comparação ao uso de redes cabeadas, como a maior flexibilidade e o menor custo de implantação. No entanto, é necessário lidar com problemas típicos das redes sem fio, como interferência e o alto nível de atenuação em pequena e larga escala. Além disso, as características do canal sem fio variam com o tempo e uma RSSFI deve ser capaz de se adaptar a essas variações para manter boa qualidade de serviço durante sua operação. Estratégias adaptativas, como a alocação dinâmica de canais, permitem lidar com os problemas mencionados. Para isso, o primeiro passo é estimar a qualidade dos enlaces, de modo que os nós da rede possam decidir se uma mudança de canal é necessária. Esta tese apresenta como contribuição um novo estimador de qualidade de enlace (LQE) e um novo tipo de nó, o nó LQE, que estima a qualidade dos enlaces em tempo real, usando informações obtidas a partir do transceptor, e informações extraídas de pacotes de dados recebidos. O estimador proposto considera problemas causados pelo perfil de multipercurso do ambiente na qualidade do canal,interferência e assimetria. Um protótipo foi desenvolvido e a solução foi validada por meio de experimentos em um ambiente industrial real. Diferente de outros LQEs encontrados na literatura, a solução proposta não gera tráfego extra na rede e não causa sobrecarga nos nós finais. Com base no LQE proposto, um novo protocolo de acesso ao meio foi desenvolvido. O protocolo usa adaptação de canal para a transmissão de pacotes de dados e salto em frequência para a transmissão de pacotes em broadcast. A taxa de recepção de pacote média na camada de aplicação permaneceu perto do pico para todos os cenários avaliados com o protocolo proposto, mesmo considerando as variações na qualidade dos canais ao longo do tempo. Os resultados indicam que o protocolo proposto apresenta desempenho superior aos protocolos de acesso ao meio definidos pelos padrões para RSSFI, em termos de confiabilidade e determinismo. Vários resultados experimentais obtidos em ambientes industriais também são descritos e é proposto um novo modelo para simulação de protocolos multicanais. O modelo é capaz de capturar os efeitos de atenuação por multipercurso, sombreamento, assimetria, as características não estacionárias do canal sem fio e a descorrelação entre diferentes canais.
Industrial Wireless Sensor Networks (IWSNs), that is used to implement monitoring and control applications, presents certain advantages when compared to wired networks, including higher flexibility and lower deployment costs. However, it is necessary to deal with typical problems of wireless networks, such as interference and a high attenuation, in small and large scale. In addition, the characteristics of the wireless channel may change over time, and an IWSN needs to self adapt to these variations to maintain a good quality of service during its operation. Adaptive mechanisms, such as, dynamic channel allocation, are used to deal with the aforementioned problems. For this, the first step is to estimate the link quality, so that the network nodes can decide if a channel change is needed. This thesis presents as a contribution a novel Link Quality Estimator (LQE), and a new type of node, the LQE node, that estimates the quality of the links in real-time, using information obtained from the transceiver, and information obtained from received data packets. The proposed LQE deals with the problems caused by the multipath profile of the environment in channel quality, interference and asymmetry. A prototype was developed and the LQE was validated by experiments in an actual industrial environment. Different from other LQEs in the literature, the solution proposed in this thesis does not cause overhead at the end-nodes and on the network. Based on the proposed LQE, a novel MAC protocol was developed. The protocol uses channel adaptation for the transmission of unicast data packets, and frequency hopping for the transmission of broadcast packets. The packet reception rate at the application layer was at the peak for all scenarios that were evaluated using the proposed protocol, even considering the variations in channel quality over time. The results indicate that the proposed protocol presents a better performance in comparison to the MAC protocols defined by the standards for IWSN, in terms of reliability and determinism. Several experimental results obtained in industrial environments are also described, and a new model for simulation of multi-channel protocols is proposed. The model includes the effects of multipath fading, shadowing, asymmetry, the non-stationary characteristics of the channel, and the uncorrelation of the different channels.

This thesis is focused on the industrial environment. This study aims to understand the difficulties wireless communications have when performing in these types of environment with a specific standard (and protocol) Zigbee. These difficulties are due mainly to the physical effects and interferences as well the electromagnetic waves from these wireless transmission signals can suffer. The background of this project is to analyze how industries can implement wireless sensor networks (using Zigbee standard) for their factories in order for them to be beneficial i.e. reliable or if it is possible. Industries normally tend to keep in the path of the old fashioned way i.e. wired systems which are more robust and can cope with the hard system requirements. Some study on these environment effects (interference as well) is performed. The results show how this (Zigbee) sensor network could be or should be implemented in order to have the best performance (disposition of devices, type of environment considering only industrial environments, etc.). Specifically, these results show that Zigbe wireless sensor networks are limited to some conditions in order to obtain the desired reliability. These conditions are that these networks must be performed in absorbing environments, LoS disposition of devices, not too long diatance between devices and not other networks in the same area using the same frequency band. The limitation of absorbing environments is because the dispersion effects in the (highly) reflective environments are critically damageful for the link. The limitation of the other devices operating in the same frequency band in a close area is due to the fact that Zigbee has no frequency diversity. Last but not least, the limitations to LoS and not too long maximum range (approximately 50 meters) are related since the range would be (much) lower than 50 meters if the communication was in NLoS disposition of devices. The noise in this environment is also studied and modeled. The results show that as the impulsive index (which is ameasure of the number of impulses that reach the receiver in a certain unit of time) takes larger values, the distribution approximates that of a Gaussian and as A takes lower values the reults show an impulsive characteristic. The Probability of error is computed for values of A less than 1, where the impulsive characterstic is shown, and as A takes larger values the error is greater.

La sécurité des systèmes de contrôle industriel est une préoccupation majeure. En effet, ces systèmes gèrent des installations qui jouent un rôle économique important. En outre, attaquer ces systèmes peut non seulement entraîner des pertes économiques, mais aussi menacer des vies humaines. Par conséquent, et comme ces systèmes dépendent des données collectées, il devient évident qu’en plus des exigences de temps réel, il est important de sécuriser les canaux de communication entre ces capteurs et les contrôleurs principaux. Ces problèmes sont plus difficiles à résoudre dans les réseaux de capteurs sans fil (WSN). Cette thèse a pour but d’aborder les questions de sécurité des WSN. Tout d’abord, nous effectuons une étude de sécurité approfondie du protocole WirelessHART. Ce dernier est le protocole leader pour les réseaux de capteurs sans fil industriels (WISN). Nous évaluons ses forces et soulignons ses faiblesses et ses limites. En particulier, nous décrivons deux vulnérabilités de sécurité dangereuses dans son schéma de communication et proposons des améliorations afin d’y remédier. Ensuite, nous présentons wIDS, un système de détection d’intrusion (IDS) multicouches qui se base sur les spécifications, spécialement développé pour les réseaux de capteurs sans fil industriels. L’IDS proposé vérifie la conformité de chaque action effectuée par un noeud sans fil sur la base d’un modèle formel du comportement normal attendu
The security in Industrial Control Systems is a major concern. Indeed, these systems manage installations that play an important economical role. Furthermore, targeting these systems can lead not only to economical losses but can also threaten human lives. Therefore, and as these systems depend on sensing data, it becomes obvious that additionally to real-time requirement, it is important to secure communication channels between these sensors and the main controllers. These issues are more challenging inWireless Sensor Networks (WSN) as the use of wireless communications brings its own security weaknesses. This thesis aims to address WSN-based security issues. Firstly, we conduct an in-deep security study of the WirelessHART protocol. This latter is the leading protocol for Wireless Industrial Sensor Networks (WISN) and is the first international approved standard. We assess its strengths and emphasize its weaknesses and limitations. In particular, we describe two harmful security vulnerabilities in the communication scheme of WirelessHART and propose improvement in order to mitigate them. Secondly, we present wIDS, a multilayer specification based Intrusion Detection System (IDS) specially tailored for Wireless Industrial Sensor Networks. The proposed IDS checks the compliance of each action performed by a wireless node based on a formal model of the expected normal behavior

Low-power and resource-constrained wireless technology has been regarded as an emerging technology that introduces a paradigm shift in a wide range of applications such as industrial automation, smart grid, home automation and so on. The automation industry has significant contributions to economic revenues, job opportunities and world-class research. The low-power and resource-constrained wireless technology has brought new opportunity and challenges for industrial automation. The solutions of such wireless technology offer benefits in relation to lower cost and more flexible deployments/maintenances than the wired solutions, and new applications that are not possible with wired communication. However, these wireless solutions have been introducing new challenges. Wireless links are inherently unreliable, especially in industrial harsh environment, and wireless interference makes the problem even worse. Low-power consumption is required and real-time communication is generally crucial in industrial automation applications. This research work addresses that industrial wireless sensor and actuator network (IWSAN) should even be designed to provide service differentiation for wireless medium access and adapt to link dynamics for scheduling algorithms on top of real-time services. Specifically, exceeding the required delay bound for unpredictable and emergency traffic in industrial automation applications could lead to system instability, economic and material losses, system failure and, ultimately, a threat to human safety. Therefore, guaranteeing the timely delivery of the IWSAN critical traffic and its prioritization over regular traffic (e.g. non-critical monitoring traffic) is a significant topic. In addition, the state-of-the-art researches address a multitude of objectives for scheduling algorithms in IWSAN. However, the adaptation to the dynamics of a realistic wireless sensor network has not been investigated in a satisfactory manner. This is a key issue considering the challenges within industrial applications, given the time-constraints and harsh environments. In response to those challenges, a protocol framework for adaptive real-time communication in IWSAN is proposed. It mainly consists of a priority-based medium access protocol (MAC) and its extension for routing critical traffic, a hybrid scheme for acyclic traffic, and adaptive scheduling algorithms. To the best of our knowledge, the priority-based MAC solution is the first priority-enhanced MAC protocol compatible with industrial standards for IWSAN. The proposed solutions have been implemented in TinyOS and evaluated on a test-bed of Telosb motes and the TOSSIM network simulator. The experimental results indicate that the proposed priority-based solutions are able to efficiently handle different traffic categories and achieve a significant improvement in the delivery latency. The hybrid scheme for acyclic traffic increases the throughput and reduces the delay compared to the current industrial standards. Numerical results show that the adaptive scheduling algorithms improve the quality of service for the entire network. They achieve significant improvements for realistic dynamic wireless sensor networks when compared to existing scheduling algorithms with the aim to minimize latency for real-time communication.

This thesis proposes a new medium access control protocol which lies on top of LoRa at 2,4 GHz. Its name is LoRaIN and, in fact, it is intended for a monitoring Industrial Internet of Things application. First, this document provides a general description of the network architecture and relative functionalities. In particular, the centralized nature of the protocol is described in detail, being a discriminating factor with the others IIoT layer 2 protocols. A fundamental feature of LoRaIN is that the devices are not battery driven and, conversely, they are charged via Wireless Power Transfer technology. In fact, an important emphasis is given to the time division between nodes charges and LoRa communications. Finally, some numerical computations have been performed to show the network performance; the latter have been taken as reference for the hands-on work.

This thesis was carried out in the context of a project developed by the university of Bologna upon commission of GD SpA, aimed at providing a new proprietary solution for a Industrial Internet of Things monitoring application. The focus is on the definition and implementation of a wireless communication protocol, which has been called LoRaIN, based on LoRa technology at 2,4 GHz and suitable for Industry 4.0 applications. LoraIN proposes a centralized approach to Network management, with a single entity keeping synchronization among devices and scheduling all the transmissions according to separated time slots, in order to avoid collisions. Distinctive features of the protocol are also its multi-hopping functionality and the possibility to deploy batteryless devices, charged via Wireless Power Transfer technology. Numerical results reported in the thesis demonstrate how LoRaIN protocol meets the application requirements.

Le but de cette thèse concerne de minimiser le temps d’échange entre les objets mobile dans un environnement industriel. Dans la première partie une étude bibliographique concernant les problèmes d’échange entre les mobiles sera présentée. Dans la suite nous avons comparé par simulation sous NS2 (Network Simulator 2) plusieurs modèles de propagation afin de sélectionner le modèle le plus adapté à notre milieu industriel. Les résultats des simulations ont montré que le modèle pr1238 est le modèle le plus performant. Ce modèle de propagation sera utilisé ensuite pour optimiser l’algorithme d’accès « back-off ». L’algorithme d’accès « back-off » utilisé dans les réseaux 802. 11 souffre de plusieurs problèmes : collision entre les données, retard de transmission des données échangées, qui est très contraignant dans les applications de temps réel. Pour surmonter ces problèmes, nous avons proposé une nouvelle méthode. Cette nouvelle méthode repose en premier lieu sur la modification des paramètres de l’algorithme de « back-off » en cas de succès et de collision afin de réduire le temps d’accès. En deuxième lieu, elle utilise un réseau de neurones pour augmenter la précision sur les paramètres du modèle
The purpose of this study is to discuss the exchanges between mobiles moving in an industrial environment. To reach this study, a simulation approach has been chosen in order reach this study. This novel method aimed to minimize the exchange time between mobiles within an 802. 11 cell. The first step of our study represents the main points arising from this choice. Initially, we described the main existing models of spread and constraints of radio propagation. The selection of relevant model propagation for the selected industrial site is based on several measurements in domain indoor. The implementation of the ITU Pr1238 model was performed by adjusting the parameters of the various models; we decided to select the model recommended by the ITU under reference Pr1238 as our model that is used for the industrial by the NS2 Simulator. The second step was to come up with a modified method of the DCF in order to minimize the necessary time so that all mobiles within the same cell of an 802. 11b network can exchange the shared information during their co-operation. The optimization of the exchanges time between mobiles was carried out by modifying the binary exponential aspect of the Back-off algorithm as a first phase to reduce the access time to the radio medium. Whereas in the second phase this modified and enhanced BEB method was supported by a Neural Network Function to give us precise output parameters. Those outputs will be learned by the Neural Network Function and will be used in the NS2 simulation to get the new results of the time delay to compare them with the standard BEB method results

Industrie-4.0 bringt eine wachsende Nachfrage an Netzwerkprotokollen mit sich, die es erlauben, Informationen vom Produktionsprozess einzelner Maschinen zu erfassen und verfügbar zu machen. Drahtlose Übertragung erfüllt hierbei die für industrielle Anwendungen benötigte Flexibilität, kann in herausfordernden Industrieumgebungen aber nicht immer zeitnahe und zuverlässige Übertragung gewährleisten. Die Beiträge dieser Arbeit behandeln schwerpunktmäßig Protokollentwurf und Protokollevaluation für industrielle Anwendungsfälle. Zunächst identifizieren wir Anforderungen für den industriellen Anwendungsfall und leiten daraus konkrete Entwufskriterien ab, die Protokolle erfüllen sollten. Anschließend schlagen wir Protokollmechanismen vor, die jene Entwurfskriterien für unterschiedliche Arten von Protokollen umsetzen, und die in verschiedenem Maße kompatibel zu existierenden Netzwerken und existierender Hardware sind: Wir zeigen, wie anwendungsfallspezifische Priorisierung von Netzwerkdaten dabei hilft, zuverlässige Übertragung auch unter starken Störeinflüssen zu gewährleisten, indem zunächst eine akkurate Vorschau von Prozessinformationen übertragen wird. Für deren Fehler leiten wir präziser Schranken her. Ferner zeigen wir, dass die Fairness zwischen einzelnen Maschinen durch Veränderung von Warteschlangen verbessert werden kann, wobei hier ein Teil der Algorithmen von Knoten innerhalb des Netzwerks durchgeführt wird. Ferner zeigen wir, wie Network-Coding zu unserem Anwendungsfall beitragen kann, indem wir spezialisierte Kodierungs- und Dekodierungsverfahren einführen. Zuletzt stellen wir eine neuartige Softwarearchitektur und Evaluationstechnik vor, die es erlaubt, potentiell proprietäre Protokollimplementierungen innerhalb moderner diskreter Ereignissimulatoren zu verwenden. Wir zeigen, dass unser vorgeschlagener Ansatz ausreichend performant für praktische Anwendungen ist und, darüber hinaus, die Validität von Evaluationsergebnissen gegenüber existierenden Ansätzen verbessert.
As smart factory trends gain momentum, there is a growing need for robust information transmission protocols that make available sensor information gathered by individual machines. Wireless transmission provides the required flexibility for industry adoption but poses challenges for timely and reliable information delivery in challenging industrial environments. This work focuses on to protocol design and evaluation aspects for industrial applications. We first introduce the industrial use case, identify requirements and derive concrete design principles that protocols should implement. We then propose mechanisms that implement these principles for different types of protocols, which retain compatibility with existing networks and hardware to varying degrees: we show that use-case tailored prioritization at the source is a powerful tool to implement robustness against challenged connectivity by conveying an accurate preview of information from the production process. We also derive precise bounds for the quality of that preview. Moving parts of the computational work into the network, we show that reordering queues in accordance with our prioritization scheme improves fairness among machines. We also demonstrate that network coding can benefit our use case by introducing specialized encoding and decoding mechanisms. Last, we propose a novel architecture and evaluation techniques that allows incorporating possibly proprietary networking protocol implementations with modern discrete event network simulators, rendering, among others, the adaption of protocols to specific industrial use cases more cost efficient. We demonstrate that our approach provides sufficient performance and improves the validity of evaluation results over the state of the art.

O uso de equipamentos sem fio em sistemas de monitoramento e controle de processos industriais vem aumentando gradativamente. Os elevados custos de cabeamento incentivam os gerentes de fábricas para que considerem o uso de sistemas industriais sem fio, uma vez que estes promovem grandes reduções nos custos de instalação finais. Entretanto, a robustez do enlace de rádio frequência e os requerimentos de comunicação em tempo real são frequentemente citados como obstáculos reais para o uso de tecnologias sem fio na indústria. À frente das demais organizações, a HART Foundation lançou em 2007 o WirelessHART, sendo este o primeiro padrão aberto de comunicação sem fio especificamente desenvolvido para ambientes industriais. Apesar de ser um protocolo seguro e de propiciar comunicação em tempo real, o estudo aprofundado do WirelessHART revela diversas possibilidades de melhorias. Nesse protocolo, o gerenciamento da rede é feito de forma centralizada, o que garante maior simplicidade e controle sobre o escalonamento, roteamento e a segurança das mensagens. Por outro lado, grandes latências, especialmente nos processos de conexão e desconexão de nós, impossibilitam o uso de dispositivos móveis ou intermitentes. A concentração do gerenciamento em um só elemento também leva à fragilidade do sistema: na falha do gerenciador central, toda rede fica inoperante. Neste trabalho, é apresentada uma arquitetura de rede WirelessHART inovadora, que utiliza coprocessadores gerenciadores distribuídos para possibilitar a descentralização do gerenciamento e consequentemente as suas vantagens. O sistema desenvolvido permite diferentes configurações descentralizadas, parciais ou totais, e com mínimas modificações no protocolo original. A arquitetura de rede proposta mantém os dispositivos de campo com suas características originais, de baixo custo e consumo, além de permitir a coexistência com equipamentos certificados. A metodologia para a descentralização é apresentada e o estudo de caso realizado permite a avaliação da proposta. A originalidade deste trabalho é verificada através do estudo do estado da arte. Os resultados obtidos de um estudo de caso demonstram o grande potencial da proposta, com reduções significativas nos tempos de agregação e manutenção da rede. A proposta de descentralização possibilita configurações e modos operacionais antes impossíveis no WirelessHART, tais como o uso de dispositivos móveis ou intermitentes e o emprego de técnicas de handover.
The use of wireless devices in industrial systems for process monitoring and control has been gradually increasing. The high costs of cabling encourage plant managers to consider the use of such industrial wireless systems, since they promote large reductions in final costs. However, the link robustness and the real-time communication requirements are frequently cited as real obstacles to the use of wireless technologies in the industry. Ahead of other organizations, the HART Foundation launched the in 2007WirelessHART, which is the first open standard for wireless communications developed specifically for industrial environments. WirelessHART is a reliable and secure protocol and provide real-time communications but the thorough study of this protocol reveals several possibile improvements. In this protocol, network management is done centrally, ensuring simplicity and control over the scheduling, routing and messaging security. Moreover, large latency, especially in the connection and disconnection processes of field devices, preclude the use of mobile or intermittent devices. The concentration of one element in management also leads to the system fragility: if the central manager fails the entire network fail. In this work, a innovative WirelessHART network achitecture is presented and implemented by means of hardware-based distributed network manager coprocessors to enable decentralization and its blessings. The developed system allows different decentralized, partial or total architectures with minimal changes to the original protocol. A hardware-based solution maintains field devices with its low cost and consumption features and allow coexistence with certified equipment. The decentralization methodology along with its originality is presented and case study allows the evaluation of the proposal. The results demonstrate the architecture has great potential with significant reductions in join and maintenance times. The proposed decentralization enables configurations and operating modes previously impossible in WirelessHART such as the use of mobile or intermittent devices and handover techniques.

A aplicação de redes sem fio vem crescendo consideravelmente nos últimos anos. Protocolos baseados nesta tecnologia estão sendo desenvolvidos para uma grande variedade de aplicações. A confiabilidade é um dos principais requisitos dos protocolos de comunicação nos ambientes industriais. Interferências, ambiente ruidoso e o grande risco das aplicações industriais que são monitoradas são fatores que elevam os níveis de exigência no que se refere à confiabilidade, redundância e segurança do protocolo. O protocolo WirelessHART é um padrão de comunicação sem fio desenvolvido especificamente para monitoramento e controle de processos com os requisitos necessários para ser utilizado em ambientes industriais. A norma do WirelessHART define diversos aspectos técnicos a serem utilizados no desenvolvimento de algoritmos. Os algoritmos de roteamento e escalonamento de mensagens são de grande relevância para o cumprimento dos requisitos temporais, de confiabilidade e segurança. Requisitos de roteamento e escalonamento são especificados, porém, os algoritmos a serem utilizados não são definidos. O objetivo nessa dissertação é analisar alguns dos principais algoritmos que tem sido propostos especificamente para o protocolo WirelessHART e apresentar um conjunto capaz de ser aplicado nesse protocolo. Análises e comparações entre os algoritmos são realizadas proporcionando um estudo aprofundado sobre seus impactos no desempenho do protocolo.
The application of wireless networks has grown considerably in recent years. Protocols based on this technology are being developed for a great variety of applications. Reliability is one of the main requirements for communication protocols in industrial environments. Interferences, noisy environment and high risk processes that are monitored are factors that increase the levels of requirements in terms of reliability, redundancy and security of the protocol. The WirelessHART protocol is a wireless communication standard specifically designed for process monitoring and control applications with the necessary requirements for to be used in industrial environments. The WirelessHART standard defines several technical aspects to be used in the development of the algorithms. The algorithms of routing and scheduling messages are highly relevant to meeting the timing requirements of reliability and safety. Routing and scheduling strategies are specified, however, the routing and scheduling algorithms are not defined for use. The goal of this dissertation is to analyze some of the main algorithms that have been proposed specifically for the WirelessHART protocol and to present a set able to be applied in this protocol. Analyzes and comparisons between algorithms are realized by providing a detailed study of their impacts on the protocol performance.

A decade ago, wireless technology was unimaginable in its application in industrial automation as wireless had poor reliability and security in the form of time delays and frame losses. Also, lack of interoperability and standards has been a barrier for wireless applications in control system. But with recent advancements in wireless technology, and with the underlying advantages of wireless like low infrastructural costs, scalability, mobility, and ability to operate in extreme and remote environments, many are seriously considering wireless for industrial automation solutions. For wireless implementation in industries, it is important to understand its characteristics - security, update rates, data types, protocols, and latency time. Protocol being an important characteristic of any communication, is to be chosen intelligently for maximum efficiency. Because of the complexity of creating a communication protocol, existing information technology (IT) protocols such as Wi-Fi, Bluetooth, and ZigBee were used in industries. But as applications widened, and interoperability became an important factor to be considered, it was required to standardize the protocols used. ISA SP100 and WirelessHART are results of this standardizing process. For the last few years, there has been a huge discussion on which of these protocols are robust and work better, and none has emerged as clear winners. The aim of this thesis is to explore the capabilities and limitations of each of these protocols for various industrial applications. This thesis considers all these protocols and helps choose the best fit for industrial applications and includes study of security, reliability, and efficiency of these protocols.
text

碩士
國立中正大學
通訊工程研究所
100
Wireless Sensor Network (WSN) has gained much attention in recent years. After being deployed in the target region, sensor nodes sense information in the region and transmit it to the base station by wireless communication and network routing technology. Due to the small size of the sensor node, the hardware resources are limited; and further, it affects the capability of computing, storage space and power supply of nodes. However, the use of WSN in industrial automation is different from that in traditional WSN. WSN in industrial automation has low tolerance on end-to-end delay. Therefore, the design of data transmission needs to provide real-time QoS. In a real-time application, the predictable bounded delay is expected. In this thesis, we propose a chain-based transmission scheduling protocol. Through the setup of multiple chains, the order of node to send data packets follows the sequential positional order of the node in the chain and furthermore these chains can provide predictable bounded delay because the number of nodes in each chain is fixed. To improve the throughput, we let each chain operate in parallel. The simulations show that the bounded delays for each node are not the same due to the dependency on their position in the sink tree and the node number of the sub-chain. The bounded delay will increase as the node degree increases.

Future wireless networks will have to handle varying combinations of multimedia traffic that present the network with numerous quality of service (QoS) requirements. The continuously growing demand for mobile phones has resulted in radio spectrum becoming a precious resource that cannot be wasted. The current second-generation mobile networks are designed for voice communication and, even with the enhancements being implemented to accommodate data, they cannot efficiently handle the multimedia traffic demands that will be introduced in the near future. This thesis begins with a survey of existing wireless ATM (WATM) protocols, followed by an examination of some medium access control (MAC) protocols, supporting multimedia traffic, and based on code division multiple access (CDMA) physical layers. A WATM link layer protocol based on a CDMA physical layer, and incorporating techniques from some of the surveyed protocols, is then proposed. The MAC protocol supports a wide range of service requirements by utilising a flexible scheduling algorithm that takes advantage of the graceful degradation of CDMA with increasing user interference to schedule cells for transmission according to their maximum bit error rate (BER) requirements. The data link control (DLC) accommodates the various traffic types by allowing virtual channels (VCs) to make use of forward error correction (FEc) or retransmission techniques. The proposed link layer protocol has been implemented on a Blue Wave Systems DSP board that forms part of Alcatel Altech Telecoms' software radio platform. The details and practicality of the implementation are presented. A simulation model for the protocol has been developed using MIL3 's Opnet Modeler. Hence, both simulated and measured performance results are presented before the thesis concludes with suggestions for improvements and future work.
Thesis (M.Sc.)-University of Natal, Durban, 2000.