The Research And Improvement Of MAC Protocol For Wireless Sensor Network Of Monitoring System Of Urban Pathway

In recent years,with the continuous development of urban rail transit system,in the process of urban rail train go line,how to train key equipment status parameters in real-time and reliable monitoring,in order to reduce accidents,ensure the safety of train operation has become the key problems of urban rail train safety monitoring system.Wireless sensor network(WSN)with its deployment of convenient,low power consumption,low cost,etc will play a significant role in the urban rail monitoring system,and the traditional MAC protocol can not meet the requirement of the monitoring system of urban rail,therefore,to better ensure the safe and stable operation of urban rail train,the monitoring system of urban rail MAC protocol research,has very important practical significance.Firstly,this dissertation introduces the basic concepts of' wireless sensor networks,the structure,the basic characteristics,the key technologies,research status and applications.Secondly,it discusses the monitoring system of urban rail transit system,focus on the content and methods of orbit monitoring system,on this basis,a track real-time monitoring of wireless sensor network is proposed,sensor nodes in the network periodically collect data,and then transfer the data to the gateway by multi-hop,the gateway sends the real-time data to a PC by GPRS and other ways.The network improves the shortcomings of low real-time in the traditional monitoring system.Then,the article researches wireless sensor network MAC protocol,and finishes improvement of S-MAC protocol.LCO-MAC only replies the ACK frame to the interested data frame.As a result,the protocol reduces the overhead control,nodes have more time to sleep,achieving the purpose of saving energy,reducing communication delays.At last,the system selects the C8051F996 microprocessor as the node data processing unit,the nRF905 rf chip,C8051F020 as nodes of wireless transceiver unit fully integrated mixed-signal system level MCU chip as the main control circuit,DS18B20 digital temperature sensor network node as the node sensor unit and EVE brand BF702338 can square lithium battery as the node power supply unit directly,based on the built a includes three wireless sensor nodes and a gateway node of wireless temperature measuring platform,and the distance from the communication on the platform,the transmission reliability and energy saving features three aspects to verify the LCO-the performance of the MAC protocol,the result of the experiment shows that the agreement on the premise of guarantce the communication distance,reliable transmission,save the sensor.