Inter vehicular communication

Inter vehicular communication is a part of intelligent transport system.  Inter vehicular studies have been conducted since 1980’s and many useful inventions like PATH, chauffeur, CarTALK 2000 etc have rolled out of the labs.

Vehicular Networks (also known as VANETs) are a cornerstone of the envisioned Intelligent Transportation Systems (ITS).

Three main applications of Inter vehicular communication are

•        Information function – distribution of road information like incidents etc to the vehicles.
•        Longitudinal control – using IVC’s capabilities for improving the road capacity.
•        Assistance systems – Assisting vehicles at the critical points like blind turns etc.

Communication structure

Inter vehicular communication systems use two types frequencies for communication between the vehicles namely 

1. Infrared frequency.
2. Radio frequency.

 Radio frequencies include VHF, micro, and millimetre waves. It is worth to note that infrared, in spite of its various drawbacks, has been adopted by most projects. The communication with infrared and millimetre waves are within the range of LOS and usually directional, whereas those with VHF and microwaves are of broadcast type. 

3G technology – The technology which is used in cellular phone is proposed for the communication between vehicles but there are some problems which have to be solved before using the 3G technologies like

•          Time synchronization
•          Radio resource management
•          Lack of centralized structure.

Inter Vehicular communication uses two type of routing protocols 

1.          Unicast routing protocol
2.          Broadcast routing protocol

Unicast routing protocols are usually position based. For application like group communication the unicast protocols are not very effective as it uses packet forwarding for information transfer.  

Broadcast routing protocol uses the flooding method for sending the information on the network. The broadcast network can be optimized according to the needs of the application. 

Group communication has been a topic of discussion for many years. Both cooperative driving and platooning which are the main applications of Inter vehicular communication need group communication. The research done on the topic elaborate the following 

1. Group communication can be achieved through reducing the group membership service to local environment.
2. Another research suggests event based middleware for the group communication.
3. One more approach suggests building the system directly on MAC layer.
4. Tracking the membership in a more easy way rather than global tracking.

Security concerns

                The Security issues with respect to Inter vehicular communication are gaining more importance day by day. Security systems like “Driver Ad Hoc Networking Infrastructure” are some of the systems used by cars. It includes both processing and wireless communication facilities, allowing each car to constitute a local communication area around itself. In this way, each car can exchange vital signs with the neighboring vehicles.

                Wireless identification of vehicles is likely to rely more and more on electronic license plates. But there have been attacks against such schemes including those against privacy of the vehicle owners.

Conclusion

In many situations, especially those related to co-operative driving, local but distributed coordination functions sitting directly upon MAC would be more efficient solutions. In addition, since vehicles will get more “smart”, partially due to the installation of IVC systems, security and privacy are becoming new concerns that both academia and industry should pay attention to. Finally, mathematical models for road traffic are important tools in developing IVC systems, because simulations are still necessary in testing large scale communication systems.