Wireless Sensor Network System For Subway Environment Perception

Along with the urban traffic is becoming more and more serious, the subway as a fastand convenient public transport has been rapid development. And the subway securityproblems are becoming another problem that the city managers must face. ZigBee is arapidly developing wireless communication technology. It can be used to rapidly set upwireless sensor network with low-power and low-cost. According to the perceptionapplication demand of current subway security environment, this paper researches anddevelops a wireless sensor network system, in order to ensure the security of the subwayoperation and provide effective environment perception implementation.Hardware system design part carried the hardware modular design according to thenetwork node hardware structure. The whole hardware system is consisted by the mastercontrol module, sensor modules and serial interface communication module. Main controlmodule has common interface compatibility on supporting the development of each sensormodule and serial port module. Different modules can be installed on the main controlmodule to be different nodes and ultimately. Then they will form a complete environmentalperception of wireless sensor network system. The software part that according to actualapplication requirements writes the upper layer communication protocol in Z-Stack, itmainly uses three methods to reduce the power consumption: through automatic adjustingof transmission power of the sensor nodes, the sensor nodes timely sleep, and the Z-Stackenergy management, and uses AES-128advanced encryption technology to improve thesecurity of data information. This paper puts forward two kinds of power adjustingmethods that can decrease the power consumption, one is based on the relay characteristicsand the other is based on the fuzzy control. Through making contrastive analysis, they allcan achieve expected effects, as in, under the premise of normal communication, thetransmission power of the sensor nodes is always made to the minimum, and its upper router receives the RSSI value that closed to-88dB. And transmission power adjustmentmethod based on fuzzy control is especially suitable for signal intensity changes relativelysevere working condition.The experiments have proved that the wireless sensor network system, which is builtin this paper, can perform the functions of collecting and transmitting the environmentalinformation, with low-power, low-cost and high security, while achieving the prospectiveresults and maintaining certain stability and feasibility.