| NB-IoT is a cellular connection technology that supports the low-power wide-area IoT in the core standards of the 3GPP organization in 2016.At present,China has completed the basic network,and its application research is becoming one of the hotspots of Internet of Things research.The traditional on-site manual update method cannot meet the needs of a large number of widely distributed and unattended terminal softwares to be regularly updated and maintained.The remote software update of terminal software has become an important topic in the application field of NB-IoT.NB-IoT terminal software remote update involves embedded software and hardware design,NB-IoT network communication,system architecture and many other technologies,and the system complexity is high.Based on the in-depth study of terminal software update and NB-IoT communication characteristics,this paper studies and applies the remote automatic update system of NB-IoT terminal software.The main contents are as follows.(?)Focusing on the complete ecosystem of NB-IoT application development,following the basic principles of software development,this paper proposes a remote update common architecture for NB-IoT terminal software,which can be abstracted as Ultimate-Equipment,Mssage Post Office and Human-computer interaction.The Ultimate-Equipment can be divided into two parts,BIOS and User,which are responsible for updating the local boot of the code data;the Mssage Post Office acts as a communication "bridge" before the Ultimate-Equipment and the Human-computer interaction;the Human-computer interaction is responsible for updating the cloud distribution of the code data.(?)Based on the analysis of NB-IoT communication characteristics,the NB-IoT terminal software update common mechanism is proposed for the problem of limited data transmission and low transmission rate of NB-IoT single-connection communication.The mechanism has response and breakpoint transmission.And the characteristics of frame loss retransmission ensure the integrity and security of the update operation.This paper also proposes an incremental update mechanism to reduce the network overhead required for remote updates and improve update efficiency.(?)Based on the common mechanism of NB-IoT terminal software update,this paper proposes the hardware and software design and programming architecture of remote update system.The remote automatic update function of the NB-IoT terminal software is implemented on the hardware platforms of S32K144 and ME3616,and carried out adaptive research on multiple hardware platforms.The remote update system given in this paper has been tested repeatedly in the design and development of NB-IoT intelligent water meter.The results show that the remote update system is stable,reliable and practical,and has achieved the expected goals of the research. |
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