Research On The Application Of ZigBee Technology In Cooperative Vehicle Infrastructure System

With the sharply increase in the number of vehicles each year,the relationship between vehicles and roads is getting worse in China transportation system.As the key technology in developing Intelligent Transportation System(ITS),Cooperative Vehicle Infrastructure System(CVIS)can not only improve traffic efficiency,but also play a dominated role in ensuring the safety of pedestrians and vehicles in transportation system.To complete cooperation between vehicles and roads,CVIS applies advanced wireless communications to transmit Vehicle to Vehicle's and Vehicle to Infrastructure's cooperative information.Therefore,the application of wireless communication technology is the key to achieve cooperation between vehicles and roads.As emerging short-range communication technology,ZigBee technology is currently the most potential development in the field of wireless short-range communication.By compared with the other short-range communication technologies,ZigBee technology has some advantages,such as large capacity,its potential in dynamic networking,good performance in extension ability,low cost and power so on.As these advantages are carried into consideration,ZigBee technology should be capable to transmit the information needed in CVIS.Firstly,the present situation of CVIS and its development and trend in the world are introduced in this paper.Based on these,the research purpose of this paper are put forward by summarizing the research gaps between our country and other countries.Then,this paper briefly presents ZigBee technology and it's characteristics.By comparing with other mainstream short-range wireless communication technologies,ZigBee technology is selected to build the information communication architecture of CVIS.Next,a CVIS framework based on ZigBee technology is purposed and specific scenarios applied in CVIS are analyzed.According to CVIS functions which need to be implemented and feasible hardware,a hardware architecture is given based on Window CE.Finally,each part of the hardware architecture such as On-Board Unit and Road-Side Unit is proposed in detail.By using the platform Visual Studio,the software of the CIVS is coded.The software system are mainly composed of five parts,such as GPS module,ZigBee module,map module,display and processing module,the human-computer interaction module.GPS module is responsible for receiving position information by GPS device,decoding it and sending useful message to Embedded host.ZigBee module receives and transmits vehicle dynamic information between V2 V and V2 I.Map module is designed to read and draw electronic map by using a map file with Shapefile format.At the same time,map matching is fulfilled by it.Display module is to display vehicle or road-side' dynamic data with a touch panel.HCI module is responsible for receiving user's command.In order to verify the functions of the purposed CVIS software,field experiments are designed in transportation system.Two typical cased are proposed.Firstly,an experiment is used for safe distance warning between vehicles based on V2 V communications.The next one is the traffic light information and vehicle dynamic information exchange between V2 I which is realized by V2 V and V2 I communications.In addition,some functions such as the dynamic networking and communication capabilities of ZigBee,vehicle positioning which is based on map matching,safe distance warning between vehicles and traffic lights information transmitting are validated by field experiments.By these experiments results,the following conclusions can be drawn:(1)the purposed CVIS architecture can be fulfilled by the application of ZigBee technology.It is evidence that ZigBee technology can be promoted to the follow-up study of CVIS.(2)ZigBee technology has a good performance on communication required by CVIS and it is capable to dynamic networking and transmitting information in a range over 400 meters.(3)vehicle positioning by map matching and the exchange of safety distance warning and traffic light information is very useful in driving and vehicle active safety can be take a step to realization by the application of CVIS.