VANET

These days I am going to chose a topic for my graduation paper. Right now one of my options is “Message Passing Protocol for VANET using geographical data”. I’ve read about this topic a lot tonight and I found it quite interesting and with immediate practical application. So I’ve put together a short presentation about VANETs.

VANET (Vehicular ad-hoc newtork)

Definition

VANETs are a form of mobile ad-hoc networks destinated to ensure communication between passengers inside a vehicle, between vehicles or between vehicles and fixed equipment, known as roadside equipment. To ensure connectivity, nowdays a small electronic device is places inside the vehicle. It’s purpose is to ensure connectivity for the pessengers without a server or any complicated configuration settings. Using this device, the vehicle becomes a node in an ad-hoc network. Besides the regular Internet connectivity, VANETs can assure some additional services, such as traffic information.

Due to the fact that the vehicles are continously moving, VANETs have the same problems like MANs, but in VANETs the vehicles must follow a given road, some some adjustments can be made in order to improve the communication in VANETs.

An advanced form of VANETs are Intelligent VANET (InVANET), that uses a great range of modern solution in order to offer the best performance for VANETs: implementations for 802.11b/g, WiMax 802.16, Bluetoth or ZigBee.

Solutions

Due to the fact that vehicles follow a path, devices such as GPS can be used to improve VANET traffic and message passing decisions.Together with VANET, they form an intelligente transportation system.

For communication VANETs are using position-based routing and Mobile Ipv6, to ensure continuity and reachability. Because current implementations for Mobile IPv6 and mobile ad-hoc networks exist, in order to get better performance for VANETs, there can be used solutions for optimizing communication mode (direct in-vehicle, vehicle-to-vehicle, and vehicle-to-roadside communication) and provides dynamic switching between vehicle-to-vehicle and vehicle-to-roadside communication mode during a communication session in case that more than one communication mode is simultaneously available.

Standards

802.11p is a standardisation draft, extending 802.11 in order to optimize it for creating ITS. The standard offer solution for improving communication performance between vehicles and vehicles and roadside equipment. 802.11p uses the licensed ITS band of 5.9 GHz (5.85-5.925 GHz)

Organizations

From 2004 till 2007, ACM hold each year a workshop on VANETs.

Communication protocol design

VANET protocols use two types of channels: PublicSafety Channel and Critical Safety Channel.

The following document from UCLA provides some recommandation about VANET implementation and communication primitives: http://www.cse.sc.edu/research/isl/docs/genericVanetAppProtocol.pdf. There is no standard VANET protocol, VANET uses communication primitives recommanded for DSRC (dedicated short range communication). Each message has a priority and a duration. There are different types of messages:

• basic safety messages – it is send through broadcast to all surounding vehicles.
• common safety messages – a vehicle may request information about another vehicle by sending a common safety message and the reply will be a basic safety message
• probe – contains state information broadcasted to all vehicles.
• emergency vehicle alert – this message is broadcasted by an emergency vehicle to vehicles surounding it

I consider the following paper to be considerably enterresting and I recommend it: Protocol Arhitecture for VANET.

Conclusion

I consider VANETs to be a good research subject. Considerring that everyone wants to be online 24/7 and that we are always moving, VANETs are a good way to improve oour online experience while getting from one place to another. Traffic jam, accidents, all these can be avoided by building VANET bases ITS.

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