Research Of Real-time Scheduling Method In Industrial Wireless Networks

Wireless networks have been widely used in the industrial field due to the advantages of low cost, fast deployment and easy maintenance etc. Industrial wireless networks (IWNs) have a higher requirement for network performance than ordinary wireless networks do, such as transmission latency, real-time and reliability etc. Transmission scheduling, as an important approach to improve network performance, is of great significance.The thesis studies on the scheduling methods from the perspectives of network topology and network traffic, aiming for improving the real-time and reducing the transmission latency in IWNs. The main tasks of this thesis are as follow:(1)The characteristics of IWNs are analyzed, and the model of network traffic is studied.(2)A dynamic scheduling method for Time Slot Allocation based on Network Topology(TSANT) is proposed. First, the network transmission plan is constructed according to the shortest path, established by using shortest path routing algorithm. Second, the transmission plan instance is generated and executed dynamically according to network traffic. Then transmission and reception slots are allocated. Through the implementation of network transmission plan, the maximum transmission latency is determined. The method ensures the real-time of network.(3)A scheduling method for Time Slot Allocation based on Delay Tolerance(TSADT) is proposed according to the time constraint of network traffic. The shortest path is also established by using shortest path routing algorithm. According to the deadline of network traffic and the transmission path of data, the method assigns priority to data transmission. Combined with the technology of data aggregation and compression, time slots are allocated to transmission links through the decomposition of transmission path.(4)The performance of scheduling methods is analyzed, and the simulation is carried out using NS-3. Results show that the methods can dramatically decrease the average transmission latency and improve data fidelity of the network.