Research On Adaptive Transmission Scheduling Mechanismial Of Industrial Wireless Network Traffic Based On TSCH

Communication networks in the industrial field generally need to have the characteristics of high reliability,low delay and high bandwidth.Therefore,the time-slot channel hopping(TSCH)protocol based on IEEE 802.15.4 has become a promising research direction in low power wireless network protocols.TSCH is a wireless network protocol based on slot coordination.It uses clock synchronization and slot allocation mechanism to realize efficient communication.Specifically,TSCH divides time into small time slots and then distributes them among different devices in the network to ensure the reliability and stability of the communication process.The TSCH protocol is mainly used in low-power wide area networks,the Internet of Things and industrial automation.However,TSCH scheduling algorithm has some problems in industrial production application,such as insufficient flexibility.It cannot flexibly allocate time slots according to different traffic and routing topology changes.To solve this problem,this paper first analyzes the characteristics and requirements of industrial wireless sensor networks,and through the analysis of relevant research literature and practical cases,summarizes the advantages of TSCH based industrial wireless network scheduling.Then,by analyzing the advantages and disadvantages of different mainstream Traffic aware Adaptive Scheduling algorithms,Enhanced traffic-aware Adaptive Scheduling Algorithm(ETASA)model design based on TSCH is proposed:(1)Traffic sensing design:The current mainstream traffic sensing algorithm uses periodic sampling algorithm,but for periodic sampling,the sampling interval is fixed,which makes the network state highly predictable and easy to produce synchronous state,thus affecting the measurement and evaluation of network performance.And in the traffic sensing technology,the selection of period sampling value is too long,can not reflect the real network traffic state.In order to better obtain real-time network traffic,ETASA uses self-similarity traffic sampling method.The core idea of self-similar sampling is to compare the change degree of network traffic in two adjacent periods of time and change the sampling interval of the next period of network traffic accordingly.Based on this idea,ETASA is designed to evaluate the increase rate of network traffic within each sampling period,so as to set the sampling interval of the next period,so as to realize high-frequency sampling when the traffic is heavy and low-frequency sampling when the traffic is small,which ensures the more accurate acquisition of network traffic status while reducing energy consumption.(2)Traffic adaptive design:Currently,mainstream traffic adaptive algorithms are mainly divided into two categories:slot frame design based on changing slot period and slot frame design based on link load distribution.ETASA uses a timeslot frame design based on link load allocation,designed to estimate the traffic of each neighbor by utilizing the incoming traffic load.First,ETASA performs an aggregate calculation based on the link traffic value N_iof each neighbor device i,and creates a common slot frame.Then,sub-slot frames of corresponding length are allocated to the neighbor link according to each traffic value N_i.The length of sub-slot frames is determined by the incoming traffic N_iof the neighbor.The handle of sub-slot frames is the cumulative value of the length of the first several sub-slot frames.Finally,ACK frame information is loaded into the transmission schedule table and sent to the sender to facilitate the next hop transmission schedule.Based on the above scheduling model design,the corresponding scheme was realized on Contiki small operating system in this paper:the code was successfully run on z1 platform by using MSP430 compiler,and the running data was collected and analyzed by using Cooja graphic simulation tool,in which the two network performance of delivery rate and duty cycle were mainly analyzed.Compared with OST,ETASA algorithm provides higher delivery rate and lower energy consumption.To sum up,this paper conducts in-depth research on the scheduling problem of the TSCH mode for industrial Internet of Things application,and proposes a traffic sensing adaptive scheduling algorithm based on TSCH.Simulation tests and experimental analysis show that the algorithm can sense changes in traffic conditions and correspondingly change its own scheduling strategy to maximize the utilization of network resources.Greatly improved flexibility and network reliability.