Research On Active Safety Model And Middleware In Vehicular Ad-hoc Networks

With the development of economic and increasing of Car Parc, traffic safety hasincreasingly become the focus of all social sectors concern. Traditional passive safetytechnology, such as belts, airbags and bumpers, are designed to reduce the harm of car crashto the people inside the vehicle, but they do not reduce the incidence of the traffic accident.And some active safety systems can make warnings for the possible risks to a certain extentwhich are based on radar technology and image recognition technology, so that the trafficaccidents will be avoided, the accident will occur early warning, in order to avoid accidents,but because of the high cost, environmental impact, small effective scope and other reasons,they can not meet the safety needs of modern traffic.In recent years, the rapid development of wireless communication technology and theautomotive industry makes it come true to solve the problem of traffic safety by sharing theinformation among the vehicles. Thus, a new active safety technology based on VehicularAd-hoc Networks is proposed. Vehicular Ad-hoc Networks called VANETs is a new mobilead hoc networks which is used on the road, it aims to realize high-speed data transmissionbetween vehicle and vehicle or vehicle and infrastructure by the roadside. By VANETs thevehicle can share a variety of information provided by the sensors(such as the location anddirection information provided by GPS devices, speed information measured by thespeedometer, the road information provided by the temperature, humidity and light sensor,etc.) to the neighbor vehicles. With these information, the active safety applications based onVANETs (VANETs Safety Applications for short) can help the driver to predict the potentialdanger and avoid accidents, thus, provide more effective security than traditional securitytechnologies.This paper selects the highway chain collision accident as an example to make a model.The model truly restores the whole scene that the car damaged in accident reminds vehicles tothe rear of it by VANETs on the highway, and depicts the relationship between the probabilityof occurrence of chain collision and the distance between the vehicle sending packet and thevehicle receiving packet, vehicle speed, road information, wireless transmission power,periodic signal transmission frequency and other parameters in VANETs. Throughexperiments and analysis, the results show that both the distance between vehicles and thevelocity exhibit a critical phenomenon to the happening probability of collisions, so it isdetermined that how to maintain a reasonable distance, velocity, transmission frequency ofaccident signals, and other parameters when VANETs is used to avoid the highway chain collision accident. It is a theoretical significance for the rationally designing VANETsSecurity Applications.In addition, compared with the traditional self-organizing network VANETs have manydifferent characteristics, such as unstable radio channel, rapidly changing topology, thus, thedevelopment of VANETs Safety Applications is still faced with many challenges. So thispaper designed and implemented a middleware framework for VANETs environment basedon traditional component-oriented middleware. This middleware can provide the support forVANETs security applications on the following three aspects:First, the complexity of the environment of VANETs Safety Applications is screened.The middleware screened the diversity of hardware platforms, operating systems andcommunication protocol standards for VANETs Safety Applications, Eliminated thedifferences between the various hardware and software, used component-based development,improved the reusability and maintenance of the system, and reduced the development costsof VANETs Safety Applications.Second, the context-aware mechanism supporting information publish/subscribe isimplemented. The collection of the context information is the basis of VANETs SafetyApplications to send out status and warning information and predict the potential danger. Thismechanism ensures that the middleware can accept the subscription from the upperapplications for a variety of context information, such as network status, device status, useroptions, and environmental information, and thereby provides data support for VANETsSafety Applications.Third, the adaptive mechanism based on multi-component-chain is implemented. TheVANETs is a self-organized network with changing rapidly topology and unstable Statusbecause of high-speed mobility of the vehicles. It requires VANETs Safety Applicationsshould be adaptive. Therefore, this paper implemented a rapidly adaptive mechanism on thebasis of the traditional adaptive middleware which used multi-component-chain structure andan application layer communication protocol based on multi-component-chain identity. It cantake the initiative to change their structure or behavior to adapt to the change of the externalenvironment, enhanced the flexibility and stability of the VANETs Safety Applications.