Research And Implementation Of Underground Wireless Sensor Network Optimization Based On 6LOWPAN Protocol

With the rise of smart mine construction,the mine Internet of Things is gradually changing the communication mode of underground coal mining.With the formation of the core position of the TCP/IP standard in the underground backbone network,how to establish a communication protocol suitable for underground data collection has been widely studied and discussed by industry scholars.The IPv6-based low-speed wireless personal area network standard(6LOWPAN)was proposed in 2012,which makes it possible to use the same standard protocol for downhole multi-sensor acquisition.In this paper,the mobile node neighbor discovery protocol of 6LOWPAN is studied.This study is mainly divided into three parts.Firstly,the basic downhole 6LOWPAN network model is constructed for the specific requirements of the smart mine,and the IPv6 address structure for communication in the model is designed.In order to complete the construction of the downhole network topology model,a grid-like network including 6LOWPAN boundary routing and alternate active-sleep node fixed nodes is designed.The system initializes the fixed node and 6LOWPAN boundary route with reference to RFC6775 standard.After the initialization,the underground backbone All initial nodes in the network are not moving.Subsequently,this paper proposes a mobile node address registration method using the modified address registration option,which is implemented by means of around inquiry NS and NA datagram.Secondly,the neighbor discovery of the node is studied in two aspects: the initialization of the downhole backbone network and the movement of the node after initialization.This paper designs and completes the mobile node neighbor discovery process,that is,the mobile node’s mobility switch during the mobile process.Combined with the network topology proposed in this paper,the mobile node discovers the neighbor association node mechanism during the mobile process.This mechanism is designed for the case that nodes move in the 6LOWPAN domain and move between domains.The datagram data format of IEEE802.15.4 beacon datagram is designed in the mobile process.In addition,using the NS2 simulation tool,taking the moving speed and node communication radius as variables,this paper simulates the three aspects of switching delay,packet loss rate,and transmission loss during moving.Comparing the experimental results with the existing mobile solutions,it can be seen that the proposed scheme has lower switching delay,packet loss rate and transmission loss when the simulation parameters are the same.Finally,relying on the hardware equipment,the communication between the node and the Internet node during the mobile process was designed and implemented,and the experimental prototype conforming to the "Coal Mine Safety Standard" was produced,and the reliable data communication was completed.This paper uses the hardware node equipped with the Contiki system to realize the communication between the proposed mobile node and any node downhole.In the communication process,Wireshark,network debugging assistant and serial port assistant is used to capture and analyze the datagrams in the process of network communication,and the result that the nodes can still communicate normally when moving is obtained.