The Research And Development Of Supporting Technologies Of Reliable And Real-time Communication In Industrial Wireless Sensor Networks

Industrial wireless technology, as instantiations of wireless sensor network technology in the industrial field application, is a newly emerging wireless communication technology for managing the short-range, low-rate information interactions among devices. It is the use of industrial wireless technology for industrial wireless sensor network, which aimed at realizing industrial on-site data collection and wireless transmission one-stop service. As the factors, such as full-space radiation means of wireless communication, the complexity of the industrial environment and so on, makes reliability and real-time of the network communication can not be guaranteed.The paper takes the problem of high-reliable and real-time communication in industrial wireless sensor network as research object, first develops hardware platform aimed at guaranteeing good communication performance, and then focuses on the technology of time synchronization and reliable routing which are the two critical supporting technologies ensuring reliability and real-time communication from software platform. And the final aim is to provide an excellent platform for high-reliable and real-time communication in network.The hardware platform is designed and implemented. And For improving the hardware communication performance without additional cost, the RF circuit directly determining the communication performance is carried out modeling and simulation using the ADS, and the impact of communication performance resulting from design parameters, such as thickness, substrate properties, and microstrip line and so on is analyzed. In the meanwhile, the test and feedback study of communication performance of manufactured nodes is carried out. The result shows that the performance of physical nodes is consistent with the simulation, and this can help avoiding blindness and enhancing the oriented-result in the design process of RF circuit.Relating to the key supporting technologies ensuring high-reliable and real-time communication in software platform, the algorithms adapting to industrial application of Pair-wise Broadcast Time Synchronization and Multi-path Routing based on Link Quality are designed and implemented according to the understanding of wireless networks in industrial application. PBTS combines pair-wise method with reference broadcast, making use of their respective advantages to achieve network-wide synchronization, and this can not only reduce dependence on specific hardware, but also reduce the synchronization overhead significantly. In the mean while, PBTS proposes message delay update circle factor which could configure algorithm according to actual synchronization requirement, which could increase the algorithm's flexibility and configurability. MPRLQ combines the steady-state link quality estimation with real-time link quality estimation based on EWMA (exponentially weighed moving average) estimator to provide reliable routing selection in face of the poor link quality in harsh industrial field, in the meanwhile, takes traffic load balancing and high real-time packet transmission requirements into account, which could improve routing reliability.Finally, all algorithms are implemented on the hardware platform. The result of the PBTS indicates that it can achieve a precision of about 20us over a signal hop and less than 50us over 6 hops, respectively, and the stability of clock error is also fine. And the result of MPRLQ reveals that it can be well adaptive to the vibration of the link quality, and well correspond with the selection strategy of the algorithm itself. All algorithms achieve the expected goal and can meet the needs of high-reliabile and real-time communication for wireless network in the field of industrial measurement and control.