Research On Wireless Acquisition Technology Of High Frequency And Low Delay Dynamic Data

Data is the means of production in the digital economy era and the key factor driving the development of enterprises.Real-time acquisition of dynamic data such as equipment operation and environment change is a practical problem for enterprises in the process of digital transfonnation.Wireless transmission technology is wi'dely favored for its simplicity and flexibility in application.However,existing wireless technologies such as NB-IoT and LoRaWAN,which focus on low-trequency applications,cannot meet the requirements of high-frequency and low-delay acquisition of dynamic data in some industrial sites.This paper studies the narrow-band wireless transmission technology with high frequency and low delay,which is suitable for industrial Internet,and applies this technology to the wireless data summary system of bearing SPC measuring instrument.According to the industrial field devices and dynamic data acquisition of high frequency,low latency of the actual demand,using LoRa spread spectrum modulation technology and a star topology,reconstructed from the data link layer,network layer,transport layer to application layer of the wireless transport protocol,the design including channel detection and retransmission,access authentication failure,cross-layer collaborative transmission,a variety of network communication mechanism,to ensure the real-time performance of the network.Compared with LoRaWAN protocol which also adopts LoRa modulation technology,the time delay is only one tenth of LoRaWAN protocol.At the same time,the multi-channel method is used to guarantee the network's high-frequency data transmission ability,and the parallel data transmission of at least 50 devices in the application scenario can be realized.In order to reduce the communication delay of LoRa wireless network,the network delay performance was analyzed based on markov chain,all possible states in the data transmission process were determined,the transition probability between states was derived,and the influence of link quality,node number and competitive window size on transmission delay was determined.In view of the fact that there may be 10-20 nodes on a single channel in the application scenario of this paper,it is determined that the value of the competition window is 40ms,so that more than 80%nodes can complete data transmission within 100ms.At the same time,through the analysis of the characteristics of dynamic data,it is found that it has a periodic rule,so the periodic combined reporting mechanism is adopted,compared with the mode of single data submission,the average delay is reduced by 70%.Considering the numerous SPC devices,frequent data communication,slow LoRa transmission rate and obvious perfonmance bottleneck of single-channel network in the application scenario,it is difficult to meet the application requirements.In this paper,a multi-channel network scheme is proposed,and a constraint fomiula for the number of channels to complete the transmission of specific data volume within a specified time is given,which can improve the network throughput and make the load of each channel more balanced at the same time.In view of the situation that 50 SPC devices in the application background of this paper generate 100 bytes of data per second for each device,the corresponding design is carried out.One downlink channel and five uplink channels are determined to ensure that any device can complete data transmission within 1s,so as to meet the requirements of the application scenario.Compared with single-channel network,net.work throughput is improved by 6 times.At the same time,the entire LoRa wireless network was tested,including distance test,communication delay test and load test.All the test results show that the whole wireless network has achieved the design goal and can meet the needs of the actual project.