Research On The Techniques In Industrial Wireless Mesh Networks

Due to the rapid development and integration of micro electronic technique, embedded computing technology and wireless communication technology, wireless sensor networks (WSN) is a novel information about acquiring and processing technology. WSN is composed of a large number of sensor nodes which are distributed randomly in monitoring regions, responsible for sensing, collecting, processing and transferring information of monitored objects for users. The rapid development of WSN technology provides the feasibility of implementation in industrial application. However, it is challenged by the harsh environment in industry field. Therefore, the related protocols and standards for industrial application are developed in recent years.This dissertation focuses on wireless protocol for industrial application. As starting with the frame introduction of industrial wireless mesh protocol according to application requirements, the architectures of two types of nodes are proposed. A hybrid routing algorithm is researched to build real-time and deterministic data transfer path. Simultaneously, the TDMA scheduling algorithm based on intelligence optimization techniques is studied for resource optimization. Furthermore, the industrial wireless mesh protocol is applied in industrial control systems based on theory research. The concrete contents of this dissertation are given in details as follows:1. Meriting the mechanism of TSMP and ISA100.11a, the framework of industrial wireless mesh protocol is proposed according to application demands. The underlying standard takes OSI7layer model for the foundation and adopts IEEE802.15.4-2006standard. The MAC layer realizes TDMA scheduling, time synchronization and communication resource allocation. The network layer takes charge of the management of communication between nodes, routing algorithm, data transmission and encryption. The application layer is composed of large amount of commands which are set by actual requirements. Finally, the simulation results demonstrate that this framework can meet the demand of time deterministic, energy-efficient and reliable transmission for industry application.2. To alleviate the bad consequences caused by the transmission uncertainty, the routing construction algorithm and fault path maintenance strategy are presented. The hybrid routing algorithm is based on shortest route setup and route pheromone diffusion. The proposed algorithm adopts the enhanced Dijkstra’s algorithm to search for the shortest route from the gateway to each end node for first route setup. And the multipath searching task is achieved by pheromone diffusion that is drew inspiration from AODV and ant colony optimization (ACO) algorithms. The proposed routing algorithm takes the path length and the number of links shared by two paths as the evaluation criteria, and introduces the minimum surplus energy node restrictions, making the data transmission scattered over many good paths by certain probability. Aimed at different path faults, the hybrid algorithm provides the corresponding measures. Finally, the simulation results demonstrate that the proposed algorithm outperforms traditional algorithms in terms of end-to-end delay, packet loss ratio and overhead in number of packets.3.In order to solve the TDMA scheduling problem in industrial wireless mesh networks, a mono-objective optimization algorithm and a multi-objective optimization algorithm are proposed for different demands, respectively. Simultaneously, state switching restriction, sleep mode operation and some other critical techniques are also embedded into this algorithm. To minimize the number of time slots, to reduce energy consumption of the network, and to shorten end-to-end delay of the packets respectively, a hybrid algorithm which combines genetic algorithm (GA) and simulated annealing (SA) is proposed. The simulation results with different kinds of networks demonstrate that the proposed algorithm has good performance. To achieve a balance between energy consumption and end-to-end delay, the TDMA scheduling problem can be formulated as a multi-objective optimization problem. To solve the above problem, an improved algorithm based on NSGA-II algorithm is proposed. The simulation results with different kinds of networks demonstrate that the proposed algorithm outperforms traditional algorithms, being able to satisfy the demands of industrial wireless mesh networks.4. According to theoretical research, a feasible architecture of industrial wireless mesh network in industrial control systems is proposed through the development of wireless gateway, terminal data acquisition node, wireless adapter and upper computer software. The upper computer software, gateway and terminal data acquisition nodes have been developed. And these developed products constitute an experimental platform. Based on this platform, some parts of the routing algorithm and TDMA scheduling algorithm have been verified in this thesis finally.