Research On Key Technologies Of Small-scale Networking Based On LoRa

The low-power wide area network is an important part of the application in the Internet of Things.It has the characteristics of wide coverage,low price,and low power consumption.It not only plays an important role in field monitoring,but also widely used in many aspects of smart cities,such as road lighting,smart electricity meters,smart water meters,smart parking,etc.As one of the most alternative technologies for low-power wide area network,Lo Ra uses license-free frequency bands and has strong anti-interference ability.It has obvious advantages and mature development in similar technologies.There are many business cases business cases in European and American.Facing the rapid growth of Io T devices,how to efficiently handle the LoRaWAN network load in a small area and improve network performance has important significance.This article focuses on the LoRaWAN urban channel environment,discusses the influence of parameters on network performance,partial orthogonality property of different spreading factors,and the MAC layer protocol.The main research contents of the article are as follows:1)Based on the NS3 simulation tool,the LoRaWAN network is modeled and simulated.Taking uplink transmission as an example,the main functions of the application layer,MAC layer,physical layer,and channel in the process of transmitting data packets and some key algorithms are given.Finally,the transmission loss model and building penetration loss model in urban scenes are introduced in detail.2)Aiming at the pseudo-orthogonality of spreading factors,an interference threshold judgment algorithm based on interference matrix is proposed.According to the total collision time of the transmitted data packet and other simultaneously transmitted data packets,the total power of the transmitted data packet subjected to interference is calculated,and the total power of the transmitted data packet is calculated,then compared with the interference matrix to determine whether the data transmission is successful.And on the basis of this algorithm,the influence of spreading factor,transmission period,duty cycle and other parameters on the performance of LoRaWAN network are discussed through NS3 simulation.3)Aiming at the problem that LoRaWAN performs media access control based on the prototype of Aloha protocol,there is a greater probability of collision during transmission.Therefore,a Lo Ra-based MAC protocol is proposed based on the CSMA protocol with RTS/CTS.The contention window of the binary exponential backoff algorithm in the CSMA protocol is improved.By slowing down the variation of the contention window,the channel access unfair problem caused by the backoff algorithm when the net is overload is solved.The simulation results show that compared with the LoRaWAN protocol,this protocol improves Lo Ra's network capacity and success rate of data packet transmission.