Research And Implementation Of Io T Communication Protocol Based On LoRa

The rapid development of the Internet of Things has led to the rise of the Low Power Wide Area Network(LPWAN).Lo Ra,as a long-distance communication technology of LPWAN,solves the problem that the traditional wireless sensor network can not have both the transmission distance and the low power consumption.The currently used protocol for Lo Ra communication is the Lo Ra WAN low-power wide area network specification proposed by the Lo Ra Alliance,which defines the Lo Ra communication specification and the structure of the network when using Lo Ra as the physical layer of the long-distance communication link.However,the existing Lo Ra WAN protocol has certain drawbacks in terms of collision rate of uplink transmission and delay of downlink communication.These defects make Lo Ra WAN unable to meet the needs of some application scenarios.The purpose of this thesis is to design and implement a Lo Ra-based Io T communication protocol that can solve the Lo Ra WAN protocol's uplink transmission conflict caused by the ALOHA mechanism and achieve lower downlink delay than the Lo Ra WAN protocol.For this reason,this thesis mainly did the following research:(1)Research on Lo Ra communication technology,in which the characteristics of Lo Ra air transmission time and wake-up mode have a guiding role in the development of Lo Ra communication protocol.The Lo Ra WAN protocol is researched and analyzed.It points out that there are many defects in Lo Ra WAN.At the same time,some mechanisms of Lo Ra WAN are worthy of reference when developing Lo Ra communication protocol.(2)Design a Lo Ra Internet of Things MAC layer protocol L-MAC based on TDMA.The L-MAC protocol divides different Lo Ra terminal nodes into different time slices based on a certain strategy to avoid uplink communication conflicts.In addition,the L-MAC protocol divides the contention time slots so that the Lo Ra terminal nodes can quickly respond to Lo Ra gateways independently of the time slot.Downlink paging,achieving low-latency downlink communications.According to the characteristics of Lo Ra communication technology design periodic listening and dormancy mechanism,so that the terminal node in the competitive time slice to achieve detection of paging signals at low power consumption.For the application scenario where L-MAC may be applied,three communication flows,namely,network access,active reporting,and paging,are designed in detail,and a frame format for each step in the communication flow is defined.(3)The contiki operating system was ported on the Lo Ra hardware platform,and the related functions and communication tests of the L-MAC protocol were implemented in the contiki operating system,and the test results were analyzed to verify that the L-MAC protocol can implement the Lo Ra network.The collision-free polling uplink communication and low-latency downlink communication.