Design And Realization Of The Vehicle-Mounted Wireless Warning System

Most of researches on WAVE technology at home and abroad just focus on theoretical research and simulation analysis currently and few of them involve to practical system development.This thesis studies and implements a vehicle-mounted wireless warning system based on WAVE protocol,which is helpful to the research and development of car networking technology.In the traffic scene of special vehicles(fire engines,police cars,ambulances,etc.)warning,emergency braking warning and construction warning,the vehicle can send early warning information to the surrounding vehicles through the system and the system will warm the driver to make the right response in time to achieve the sharing of information between vehicles when the vehicle receives the warning information from the other vehicles,which can help to reduce the occurrence of traffic accidents.Furthermore,this method is more efficient compared with the traditional traffic warning mode(brake tail light,whistle,etc.).The vehicle-mounted wireless warning system designed in this thesis works in the 5.9GHz band and it supports communication with WAVE protocol.To meet the high delay requirement of the IOV communications,the QNX microkernel real-time operating system is chosen as the software platform and the wireless communication module connects the main board of terminal through SDIO interface.The design of the software structure for the whole system will be completed on the basis of the requirements analysis for the application scenarios and functions.The task of this thesis will focus on the developments of the wireless network driver and middle-tier application programs.(1)In the development process of wireless network driver,the design idea that the top half and the bottom half are separated is used,which reduces the complexity of the achievement of wireless network driver effectively,improves the stability of the wireless network driver and shortens the development cycle.It adopts a non-blocking message delivery mechanism to design the command channel of driver and middle-tier application,which can avoid system disorders effectively.The wireless network driver realizes the transmission of WSMP(WAVE Short Message Protocol)and IPv6 data.It is necessary to note that WSMP(WAVE Short Message Protocol)and IPv6 are included in the WAVE protocol standard.(2)The development of middle-tier application uses multi-thread idea.In the process of development,various synchronization and mutual exclusion mechanisms is employed to control the dispatching and block of the process,which prevents the deadlocks that arise easily in multithreaded programs appearing.The function of middle-tier applications including generating the warning information according to the data from the vehicle sensor and the command sent by the handheld device,assembling the warning information into a CAM(Cooperative Awareness Message)packet,broadcasting the CAM packet to the surrounding vehicle through the wireless network drivers,analyzing the CAM packet received from the other vehicles,confirming warning information on the basis of the analytical results and the predesigned strategy and sending the warning information to the driver through the handheld device to the driver early warning.The test environment will be constructed in this part to finish the test for communication function,GPS function,warning function and the stability of the whole system of the vehicle-mounted wireless warning system.Then,the attention will be turned to analysis and conclusion of the test results.It turns that the vehicle-mounted wireless warning system designed in this thesis can meet the expectation requirements and realizes the communication among vehicles under the environment on board and the basic early warning function.Furthermore,it is stable and reliable.