Research On Network Transmission Mechanism Of Coding Reconfiguration Based On LoRaWAN Protocol

The network of LoRa has the advantages of simple architecture,flexible scale of network construction,low operation cost,data security and control.With the gradual maturity of LoRa technology and the gradual standardization of the upper layer protocol,LoRaWAN procotol,the LoRa protocol becomes prevalent for modern Io T applications,and the problems of LoRaWAN protocol are gradually exposed.In this thesis,for the problem that the terminal access process of LoRaWAN protocol is vulnerable to security threat and the collision is easy to occur in the process of multi-node competition intervention channel,an mechanism of access and transmission based on coding reconstruction is proposed to improve the security in the process of access and reduce the delay caused by collision in the process of data transmission.In the terminal network access and activation phase,this thesis specifically proposes a two-way authentication mechanism based on frame reconstruction.This mechanism improves the encryption level of the terminal connection request frame and completes the negotiation of reconstruction rules through the encoding and reconstruction of the data frame.On this basis,by judging whether the reconstructed data frame conforms to the reconstruction rules agreed by both parties,the two-way identity authentication of the network access authentication process between the terminal and the server is realized,and the security of the system network access process is improved.Perform modeling and simulation on the OPNET simulation platform to realize the two-way authentication process between the terminal and the server in the network access process.Tracking and comparing various parameters proves that the improved two-way authentication network access mechanism can significantly improve the security of the system,and as the reconfiguration rule update cycle is shortened,the two-way authentication mechanism is activated more frequently,and the security is improved more obviously.The energy consumption generated by this mechanism is calculated,and the result shows that compared with the standard LoRaWAN protocol terminal network access process,the energy consumption generated by a two-way authentication process increases significantly.However,after the introduction of the reconfiguration rule update mechanism,the increase in energy consumption generated by the system as a whole is within a controllable range.In the terminal data transmission phase,the terminal channel access in the LoRaWAN standard protocol uses the ALOHA algorithm.This thesis improves on the data collision and transmission delay caused by ALOHA algorithm,and proposes a channel access algorithm that judges the identity of the node according to the code sequence carried by the node,and performs priority transmission according to the identity of the node.The algorithm stipulates that important nodes will reserve and occupy the time slot in the current time frame before data transmission to ensure priority transmission of important node data,reduce data transmission collision rate,and reduce transmission delay.The node channel access process is analyzed,and the system recognition rate and data transmission delay in the data transmission stage are simulated and verified.The results show that the improved channel access method can effectively reduce the probability of data collision.By counting the number of reserved nodes,The algorithm realizes the on-demand allocation of time slots,greatly reducing the waste of idle time slots,increasing the system recognition rate by more than 40%,and reducing the data transmission delay.