Design And Implementation Of Wireless Relaying Technology For IoT Applications

With the broad market demand of the Internet of Things,the number of IoT devices has exploded.The demand for mass device connection has promoted the development of low power consumption and wide coverage wireless communication technology research.Among them,LoRa wireless communication technology has attracted extensive attention from researchers at home and abroad due to its low power consumption,wide coverage,unlicensed frequency band,low deployment cost and other characteristics.On the other hand,specific application scenarios such as extensive ranches,fields and basements have higher requirements for LoRa coverage.Wireless relaying technology can effectively expand the communication coverage and improve the capacity of edge users.Therefore,this thesis focuses on the design and implementation of wireless relay technology based on LoRa.The introduction of this thesis firstly introduces the research status of wireless relaying technology based on LoRa.In the second part,LoRa wireless communication technology is briefly summarized,and then the MAC layer protocol and communication protocol bet-ween LoRa gateway and server are introduced in detail.Then,the common network topology in wireless sensor networks,including planar network topology,chain topology and tree topology,are introduced in detail,and their advantages and disadvantages are analyzed.Then,routing discovery and manitance of common wireless routing protocols are analyzed and summarized.In the third part,this thesis studied the standard network architecture of LoRa WAN(LoRa Wide Area Network)and other wireless relay network architectures based on LoRa,then a wireless relay network architecture based on LoRa gateway is proposed.On this basis,the functional modules of LoRa wireless relaying gateway is analyzed,and the hardware of gateway is designed and implemented.Finally,the software platform is built and the communication performance is tested.The results verify the LoRa and wireless relay communication performance of the gateway.In the fourth part,two wireless relay strategies based on pass-through mode and Mesh networking mode are proposed.For applications in wide areas,this theis proposes a wireless relay strategy based on pass-through mode based on the characteristics of LoRa communication system and flood routing protocol.The feasibility of the strategy was verified through simulation and indoor test.The test results showed that the scheme could report terminal node data to the server through 2-hop relay,and the average transmission delay of upstream and downstream is maintained in tens of milliseconds,indicating that the relay strategy was effective.For the urban application scenario,this thesis proposes a wireless relay strategy for Mesh networking based on the research of HWMP(Hybrid Wireless Mesh Protocol)protocol.Through simulation and testing,it shows that the scheme can effectively improve the coverage and edge transmission rate.