Reducing Interferences in VANETs

By Admin on

Vehicular ad hoc networks (VANETs) are a class of wireless networks that is expected to have a key role in the intelligent transportation systems of the future. Already in recent years, the U.S. Federal Communications Commission and the European Telecommunications Standards Institute have allocated spectrum for such systems, and an IEEE communications standard for them is under development.

VANETs provide vehicle-to-vehicle and vehicle-to-roadside communication in order to support two main types of applications: safety applications such as road-hazard notification and sending emergency

messages from an accident site, and comfort applications such as advertisements, parking space availability, traffic estimation, and traffic-jam notifications. Despite being a subclass of mobile ad hoc networks (MANETs), VANETs have fundamentally different behaviour  in that their nodes are limited to move along roads, have no power constraints, have small network diameter, and may undergo rapid topology changes, for example when cars bypass each other in an intersection or when highways split before an interchange. VANETs also have different requirements for routing. While MANETs usually use topology-based table or source routing algorithms , these are not applicable for VANETs because of their highly dynamic nature.

Specific Characteristics of VANET 

High Dynamic Topology : VANET have very high dynamic topology .The communication links between node changes very rapidly. Communication between two nodes remains for very less time. For example if two vehicles moving away from each other with a speed of 25m/sec and if the transmission range is about 250m, then the link will only last for only 5 seconds ( 250m/ 50ms-1). So this how highly dynamic topology is present in VANET.

 Frequent disconnected Network : From the above characteristic we can see that connection between two or more vehicle remains for 5 second or so. To maintain the continuous connectivity vehicles needs another connection nearby immediately. But if failure occurs vehicles can connect with Road Side Unit (RSU). Frequent disconnected network mainly occurs where vehicle density is very low like rural area. 

Mobility Modelling and Prediction : The above two features for connectivity needs the knowledge of positions of vehicles and their movements but this is very difficult to predict since vehicle can move randomly and it does not have a pattern. So mobility models node prediction which based on the study of predefined road roadway model and vehicle speeds are use. 

Communication Environment : The mobility model highly varies in different environment form rural area to urban area, from highways to that of city environment. So mobility modelling and vehicle movement prediction and routing algorithm should adapt to these changes. For highways mobility models are very simple because vehicle movement is one dimensional. But in case of city environment lots of vehicle present different obstacle like building are present it makes communication application very complex in VANET..

 Hard Delay Constraints : Safety aspect like accident, sudden break and emergency call of VANET application depends upon the deliver time of data. It cannot compromise for data delay in this type of application. Therefore hard delay constrain is more important in VANET than high data rate. 

Interaction with on-board sensors : The on-bard sensor are present in the vehicle. These sensors are used to find vehicle location, vehicle speed and vehicle movement these informations are then used for effective communication between vehicle.

 Applications Of VANET 

The primary goals of VANETs are to improve safety on the road. To achieve this, the vehicles act as sensors and exchange messages to different vehicles this messages include information like speed of vehicle, condition of road, Traffic density. This enables the drivers and authorities to react early to any dangerous situations like accidents and traffic jams. But the recent research in the field of VANET have discovered many applications and technologies.

 Type-1:Application Assistance for Safe Navigation This applications manages different critical aspects of traffic safety. Several services can be offered, among them are the following:

 • Application for avoiding collision through distance calculation between two vehicle it can use sudden braking system. 

 • Application for detection of hazardous and dangerous driving conditions. This conditions can be damaged road, blocked road, if road is covered with snow or mud.

 • Application for emergency call services after an accident occurs here the vehicle can automatically call to authority if an accident occurs. 

• Applications for detecting rogue drivers which are disobeying traffic rules like crossing speed limit, talking in phone while driving, driving in the wrong side of the road. 

Type-2:Application for Traffic Regulation and Internet Connectivity The second types of applications are the following: • Application forAdvanced Navigation Assistance (ANA) such a car park formation, real time vehicle congestion information, expected weather condition for driving , etc., 

• Internet connection services can be provided to vehicle added for travel comfort and improved productivity. This be done by data transfer between vehicle and road side unit. Abbreviations 6

 • Chatting services between users of the same root, This can improve driving safety one driver can send immediate warning message to other driver, and 

• Application for advertisement of local/nearest service stations, nearest hotel, shops, mall.

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