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In the industrial automation, Industrial Wireless Sensor Networks (IWSNs) have been increasingly applied due to a great number of benefits such as convenient installation, flexible deployment and cost efficiency. Compared with conventional wireless systems, IWSNs have more stringent requirements communication reliability and real time performance. However, IWSNs are frequently deployed in a hash industrial environment with electromagnetic disturbances, moving objects and non-line-of-sight (NLOS) communication. Because of the vulnerability of wireless signal, IWSNs are under high risk oftransmission failures, which may result in missing or delaying of process orcontrol data. For industrial automation, missing the process or control deadlineis intolerable, which may terminate industrial application and finally result in economic loss and safety problems. From hierarchy point of view, the high communication reliability and low communication latency can be achieved from different network layers. OnMAC layer, existing protocols in IWSNs only provide automatic repeat request (ARQ) to improve reliability at the cost of real time performance. Analternative method is to apply Forward Error Correction (FEC) mechanism on MAC layer to provide more reliable transmissions and reduce acknowledgement messages by recovering error data. On network layer, routing protocolplays an important role in both communication reliability and latency. Traditionalrouting protocols in IWSNs are either hardly able to fulfill both of these requirements or overcomplicated.In this thesis, we initially explore the possibilities of introducing FEC intoIWSN under the requirements of the existing standard on MAC layer. Then we propose compatible and flexible FEC schemes on MAC layer for IWSNs without violating the standard format. Routing protocols based on flooding are proved to increase the Packet Delivery Ratio (PDR) by transmission diversity.We propose reliable and robust routing protocols with respect to high reliability and real time performance for IWSNs.

Along with the quick development of wireless communication technologies, industrial automation networks are also in unceasing evolution. Industrial wireless sensor and actuator networks (IWSAN) have been increasingly adopted in industrial automation systems. Although there are a number of advantages of replacing cables with wireless links, such as cost reduction, enhanced scalability and flexibility, the stringent requirements on communication reliability and meeting firm deadlines from industrial mission-critical applications must still be fulfilled. Also, transmissions over wireless channels in industrial environments are prone to noise and interferences, resulting in frequent erroneous packet deliveries. Although industrial automation systems are usually designed to be tolerant of certain communication errors, successive transmission failures may still cause downtime of industrial applications, which might lead to significant economic losses or even serious accidents. This thesis addresses the problems mentioned above and aims to provide reliable and deadline-constrained communication via IWSANs for industrial automation systems. On the MAC layer, existing IWSAN standards utilize automatic repeat request (ARQ) to improve reliability at the cost of additional transmission latency. An alternative method is to use Forward Error Correction (FEC) schemes to provide reliable communication by recovering erroneous data and avoiding unnecessary retransmissions. On the MAC layer, Time Division Multiple Access (TDMA) is usually applied in current IWSAN standards for collision-free and deterministic communication. An inappropriate scheduling scheme may introduce high transmission jitter and degrade the quality of control. On the network layer, routing protocols play an important role in both communication reliability and latency. Existing solutions are either hardly able to fulfill all stringent requirements from the mission-critical industrial applications, too complicated to be realized, or lack verification in reality. The contributions of this thesis consist of (i) the possibilities of using FEC schemes in IWSANs is explored under the requirements of existing standards on the MAC layer. A compatible and flexible FEC scheme on the MAC layer for IWSANs that does not violate the standard is proposed and evaluated by simulations. (ii) To guarantee an acceptable control quality, a TDMA scheduling scheme is presented aiming for low communication jitter, and it is compared to classic scheduling schemes. (iii) The advantages of exploiting flooding in IWSANs is discussed; a reliable controlled flooding-based routing protocol is proposed and compared to both traditional routing protocols and other flooding-based protocols. (iv) A complete IWSAN platform is built and the whole protocol stack is implemented. Measurements were conducted in a real industrial environment to verify the correctness of the proposed solution.