Intelligent Transportation using VANET

-  Mainak Ghosh and Sumit Goswami 

Can vehicles be made intelligent enough to guide their drivers in situations

like traffic congestion and accidents? Providing intelligence to vehicles means

loading them with sensors which will be controlled by a telematics box inside

the car. The box in turn would communicate with the driver and will be its

guide. Vehicular Adhoc Network (VANET) is an important component of Intelligent

Transportation Systems, which has a future potential in terms of a rich set of

applications that it can provide to its customer.

VANET is a special class of Mobile Adhoc Networks (MANET), in which the nodes

are the vehicles which communicate with other vehicles or with the base station

which acts as a roadside infrastructure for using security and services

application. Though the nodes are mobile in VANETs as well as MANETs, the

mobility in VANET is constrained to the boundaries of the road unlike the nodes

in MANETs, where movement is more random in nature. Nodes in VANET are also

characterized by high node mobility and fast topology changes. Unlike MANET,

power is not of great concern in VANETs as the vehicle batteries have sufficient

and rechargeable power. The concept of network vehicle was first proposed by a

team of engineers from Delphi Delco Electronics Systems and IBM corporation in

the year 1998.

Applications of VANET

The three major classes of applications possible in VANET are safety oriented,

convenience oriented and commercial oriented. Safety applications will monitor

the surrounding road, approaching vehicles, surface of the road, road curves

etc. . They will exchange messages and co-operate to help other vehicles out

under such scenario. Though reliability and latency would be of major concern,

it may automate things like emergency braking to avoid potential accidents.

Convenience application will be mainly of traffic management type. Their goal

would be to enhance traffic efficiency by boosting the degree of convenience for

drivers. Commercial applications will provide the driver with the entertainment

and services as web access, streaming audio and video.

Safety Application: Safety applications would be Slow/Stop Vehicle

Advisor (SVA) in which a slow or stationary vehicle will broadcast warning

message to its neighbourhood. Another similar type of application is emergency

electronic brake-light (EEBL). In Post Crash Notification (PCN), a vehicle

involved in an accident would broadcast warning messages about its position to

trailing vehicles so that it can take decision with time in hand as well as to

the highway patrol for tow away support. Road Hazard Control Notification (RHCN)

deals with cars notifying other cars about road having landslide. Another

related application would be road feature notification which deals with

notification due to road curve, sudden downhill etc. Cooperative Collision

Warning (CCW) alerts two drivers potentially under crash route so that they can

mend their ways.

Convenience Application: Congested Road Notification (CRN) detects and

notifies about road congestions which can be used for route and trip planning.

TOLL is yet another application for vehicle toll collection at the toll booths

without stopping the vehicles. Parking Availability Notification (PAN) helps to

find the availability of slots in parking lots in a certain geographical area.

Commercial Application: Remote Vehicle Personalisation / Diagnostics (RVP/D)

helps in downloading of personalized vehicle settings or uploading of vehicle

diagnostics from/to infrastructure. Service Announcements (SA) would be of

particular interest to roadside business like petrol pumps, highways restaurants

to announce their services to the drivers within communication range. Content

Map Database Download (CMDD) acts as a portal for getting valuable information

from mobile hotspots or home stations. Using Real Time Video Relay (RTVR),

on-demand movie experience will not be confined to the constraints of the home

and the driver can ask for real time video relay of his favourite movies. More

details of the applications is available at www.geocities.com /telbatt/Bai_Aut

onet06.pdf.

Components of VANET enabled vehicle

The components of a VANET enabled Vehicle include computer controlled devices

and radio transceivers for message exchange. The protocol that has been

standardized for communication in VANET is DSRC, which has a communication range

of 300 mts to 1 km. The roadside base station provides information to the driver

throughout his journey so that he can find a best route to his destination. The

information is periodically exchanged.

Automotive Sensors for Position Verification: Sensors in VANETS can be

classified into two types: autonomous sensors and co-operative sensors.

Autonomous sensors include Acceptance Range Threshold (ART), which is based on

the observation that all radio networks have a maximum communication range,

Mobility Grade Threshold (MGT) which is based on the assumption that the nodes

can move only at a maximum speed, Maximum Density Threshold based on the

assumption that only a restricted number of entities can reside in a certain

physical area. These aim at preventing so called Sybil attack in which a node

can create multiple copies of itself. Some other sensor includes map based

verification overhearing etc. Cooperative sensors include techniques like

proactive exchange of neighbour table to check if the positions received

correspond to their own data and reactive position request where sensors

co-operate on demand for position verification.

Communication: The DSRC spectrum is divided into seven 10MHz wide

channel. Channel 178 is the control channel which is restricted to safety

communication. The extreme two channels on either side are reserved for accident

avoidance application and high power public safety communication usages. The

rest are used for both safety and non safety applications. The IEEE has proposed

the following standards for VANETs: IEEE P1609.1, P1609.2, P1609.3 and P1609.4.

IEEE P1609.1 is for Wireless Access for Vehicular Environments (WAVE) Resource

Manager. It defines services and interfaces as well as message formats. IEEE

P1609.2 is a standard for vehicular network security which includes message

formatting, processing and exchange. IEEE P1609.3 defines routing and transport

services and thus is an alternative to IPv6. IEEE P1609.4 provides

specifications of the multiple channels in the DSRC standard. The WAVE stack

uses a modified version of IEEE 802.11a known as IEEE 802.11p for its MAC layer

protocol. It uses CSMA/CA as the basic medium access scheme. By using the

orthogonal FDM system, it provides a communication range of 1 Km while taking

into account high absolute and relative velocities, fast multi-path fading and

different scenarios.

Threats : The prime concern that has plagued many VANET researchers is

the security of these networks. Take an example of two cars moving on a single

lane on a road. The car that is trailing behind can send a false message saying

that there is a chaos ahead due to a crashed car. The car in front on receiving

this message may believe this hoax to be true and take a detour leaving a

less-traffic road for the malicious driver behind. This is one possible misuse

of the several applications talked about here. Similar misuse can create havoc

in systems where safety is of primary concern. An obvious solutions that has

been looked into is asymmetric key based authentication. Few other possible

attacks that have been considered as a threat to these networks are bogus

information attack or disruption of network operation by jamming the wireless

channel which leads to denial of service (DoS). There can also be attacks like

cheating attack where identities, speed or position can be faked. Identity

disclosure attack can be performed by a global observer who has an access to all

the data gathered through these networks.

Security: The main challenge in providing security in VANET depends on

privacy, trust, cost and gradual deployment. Some existing security tools in

some countries include electronic licence plates (ELP), which are

cryptographically verifiable numbers equivalent to traditional license plates

and help in identifying stolen cars and also keeping track of vehicles crossing

country border, vehicular public key infrastructure (VPKI) in which a

certification authority manages security issues of the network like key

distribution, certificate revocation etc., event data recording by which

important parameter can be registered during abnormal situation like accidents

etc. Tamper proof hardware is essential for storing the cryptographic material

like ELP and VPKI keys for decreasing the possibility of information leakage. To

keep a tap on bogus information attack, data correlation techniques are used. To

identify false position information, secure positioning techniques like

verifiable multilateration is commonly used.

Conclusion

VANET is definitely something to lookout for in the future. A lot of theoretical

work has been put into realizing these networks and few experiments has been

performed to validate this theory as cost of setting up this architecture is

high, but more such efforts can be expected in near future. A successful

vehicular network will open up a plethora of services to a huge number of

audience which will turn out to be life saving as well as fun.