Design And Implementation Of Transmission Strategy For LoRa System

In recent years,with the continuous development of the Internet of Things technology,the Low-Power Wide-Area Network(LPWAN)for massive device access has been widely concerned.LoRa(Long Range)technology is a typical LPWAN technology suitable for multi-device and low power consumption.However,with the increase of the number of access nodes and the frequent transmission of data,LoRa network will have problems such as downlink data collision,data arrival timeout and channel contention,which will lead to the deterioration of network performance.In order to solve the above problems and improve the network performance,this thesis designs and implements an improved downlink data transmission strategy for multi-node LoRa network.Specific research contents include:Firstly,this thesis makes a deep research on the existing network design and protocol of LoRa technology,focusing on the conflict problem of the downlink multi-node data transmission in Class B mode in LoRa WAN protocol.It points out the imperfections of the protocol design in the transmission process and proposes the improvement direction.Secondly,in order to solve the problems of data loss or delay in delivery caused by multi-node conflicts,this thesis designs a set of downlink transmission strategy for multi-node applications.The strategy designs and implements the downlink transmission process,which is divided into data generation and caching,downlink queue construction and data delivery in sequence.On this basis,this thesis further designs an improved strategy based on the minimum total delay to meet the data priority and node fairness,and it improves the downlink transmission process.Then,in order to verify the above transmission flow and improved strategy,this thesis designs and implements each module of LoRa network based on NS3 network simulation software and constructs the corresponding network simulation platform.Through simulation,the communication performance of LoRa network is tested such as data transmission success rate and transmission delay under different transmission rates and node numbers,thus verifying the performance advantages of the improved strategy proposed in this thesis.Finally,the improved transmission strategy is developed in LoRa system,and the actual performance is tested.On the hardware,the LoRa node development board is designed to realize and test the corresponding functions.In the aspect of software,the downlink transmission process and improved transmission strategy are realized.In this thesis,a test environment is built to test the actual function and performance of the improved transmission strategy in LoRa system.The experimental results show that the improved strategy realizes the schedulable two-way communication.While meeting the success rate of data transmission,it effectively reduces the total delay of downlink transmission during multi-node access.