Tuesday, March 5, 2013

Towards Intelligent Transportation Systems (ITS)

Day by day, the amount of vehicles in the roads is increasing. Proportionally to it, the amount of road side accidents and the traffic jams are increasing. Those traditional traffic controlling mechanisms, rules and regulations are unable to control this increasing issue anymore. This is where the need for intelligent transportation systems arise. We need smarter ways to coordinate vehicles on the road so that our transportation system becomes more efficient, safe and human friendly.

Vehicles mounted with sensors and wireless communication units are such a way towards implementing intelligent transportation systems. While moving on the road these vehicles can exchange valuable information to supplement safe and efficient driving. In addition to the vehicles, some base station units mounted in road sides can provide and gather information. These kinds of networks builds the new research field called Vehicular Ad-hoc Networks (VANET) which is a special case of the Mobile Ad-hoc Networks (MANET). VANETs differ from MANETs in various ways. One important aspect is the high mobility of nodes in vehicular networks since motor vehicles are moving so fast from each other on the road. VANETs differ from Wireless Sensor Networks (WSN) since VANET nodes virtually does not suffer from any resource constraint since power and hardware resources are easily available to nodes mounted in automobiles.

A key challenge faced by VANET researchers is how to provide communication links between vehicles as they are travelling very fast from each other on the road. As an example when two vehicles move to opposite directions passing each other at a high speed, the amount of time they are in each others wireless transmission range can be few seconds or less. Therefore if messages has to be passed from one to another, it should be done so quickly. But in traditional wireless networks, the connection establishment take some considerable time which is not acceptable in VANET scenarios. For example if the network uses IEEE 802.11 for communication, the two vehicles might not be able set up the connection before they go far away from the transmission ranges of each other.

On addressing these issues, researchers have made some improvements to the above standard which is considered as IEEE 802.11p and it is specifically designed to cope with high node mobility condition in VANETs. Another standard called IEEE 1609 is also have introduced which runs on top of IEEE 802.11p layer to provide further necessary functionality for IEEE 802.11p protocol. Altogether we call this WAVE (Wireless Access in Vehicular Environments) protocol. There are lot of active research going on in this area, so we can hope we will have VANET equipped automobiles in our roads in the near future.

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