Study On Low Power Consumption And Reliability Of Wireless Communication Network In Smart Parking System

While people enjoy the convenience of vehicles,they also face the problem of parking in city.It can be predicted that in the near future,the demand for intelligent parking systems will grow rapidly in city.For easy installation and later maintenance,a intelligent parking system based on Wireless Sensor Networks is a good choice.Wireless Sensor Network has the advantages of rapid deployment and cooperative sensing.However,sensor nodes are generally powered by batteries.The energy is very limited and the application environment is harsh.Therefore,how to ensure the reliability of the wireless communication network and minimize the power consumption is a key issue in intelligent parking system.Two kinds of intelligent parking system based on Wireless Sensor Network using different network topology are designed and deployed in the underground parking lot in this thesis.One uses a star network topology,and the other uses a self-organizing clustering network topology.The sensor nodes have two working modes.The sensor nodes enter test mode first and then enter actual operating mode.This thesis debugs the vehicle detection algorithm in test mode.In test mode,the system uses a many-to-one network topology.In many-to-one network,large amounts of data may cause network congestion.To solve this problem,this thesis adopts a congestion detection method based on queue length and a congestion elimination mechanism based on sample rate and packet adjustment.In actual operating mode,a low-power data transmission strategy is designed to maximize the life of the node.The strategy mainly has three measures to reduce power consumption: periodic wake-up,low-power idle waiting,and event-driven data transmission strategy.In addition,a random backoff data retransmission strategy is designed for packet recovery.The strategy takes the effect of hidden node into account.In the experimental part,this thesis first validates the effectiveness of the low-power data transmission strategy and random backoff data retransmission strategy.The low-power performance comparison results show that the lifetime of a sensor node in self-organizing clustering network can reach 6.5 years While a sensor node in star network can reach 2.3 years by using a 2200 mAh battery with the low-power data transmission strategy.The network performance comparison result verifies that the random backoff data retransmission strategy designed in this thesiscan effectively improve the network reliability.In addition,the system is tested in actual applications.The test results show that the average accuracy rate of the detection algorithm used in this thesis is 98.5%,the average packet loss rate of the star network is 1.73%,and the average packet loss rate of the self-organizing clustering network is 2.06%.