1. INTRODUCTION

1.1 Introduction

The vehicle-to-vehicle (V2V) communication platform is currently a popular research

topic, with several different approaches. Many approaches exist, each with a slightly different

focus. Traffic safety enhancement is the driving factor in many approaches, typically leading to a

solution where sensor data from vehicles and roadside units is used for providing accident and/or

weather warnings to roadside units and vehicles. Similarly, observations of and information on

traffic are used to increase efficiency of road network usage.

Also, the capability for continuous communication is an important goal. However,

bringing together the competing goals of instant data delivery required by safety applications and

bidirectional data access with relatively high capacity has not gained much attention.

In the Car link project the aim was to build more comprehensive solution for vehicle-to

infrastructure (V2I) and V2V communication purposes. The main challenges in our approach

were to tackle the communication environment between fast and independently moving vehicles,

efficient and fast delivery of critical data regardless of the location or presence of other vehicles,

and generation of services that not only enhance traffic safety and efficiency, but also thoroughly

exploit our platform capabilities. We have also considered the special cases of commercial

platform deployment phase and operation in rural areas where there is no high density base

station network in use, but we should still be able to provide an (almost) equal level of services.

The ultimate goal of this concept is to allow V2I and V2V communication. By aiming at

architecture for a commercial platform, we cannot expect any company to deploy a high-density

network throughout the operating area instantly, but instead need to provide a solution that can

provide a decent level of operability with minor installations (coarse base station network) and

expand it based on commercial success.

For this purpose we have employed hybrid communication of General Packet Radio

Service (GPRS) and wireless networking. Wireless networking stands for the ultimate

communication platform, while GPRS’s primary purpose is to provide an alternate

communication solution for cases of system failures or out-of-range locations.

Especially in the platform deployment phase and rural areas, GPRS plays an important

role. In this article the concept of the Car link platform is presented. The simulations, pilot

testing, and analysis evaluate the basic communication efficiency of the platform.

The main motivation for vehicular communication systems is safety and eliminating the

excessive cost of traffic collisions. According to World Health Organizations (WHO), road

accidents annually cause approximately 1.2 million deaths worldwide; one fourth of all deaths

caused by injury. Also about 50 million persons are injured in traffic accidents. If preventive

measures are not taken road death is likely to become the third-leading cause of death in 2020

from ninth place in 1990

However the deaths caused by car crashes are in principle avoidable. US Department of

Transport states that 21,000 of the annual 43,000 road accident deaths in the US are caused by

roadway departures and intersection-related incidents. This number can be significantly lowered

by deploying local warning systems through vehicular communications. Departing vehicles can

inform other vehicles that they intend to depart the highway and arriving cars at intersections can

send warning messages to other cars traversing that intersection. Studies show that in Western

Europe a mere 5 km/hr decrease in average vehicle speeds could result in 25% decrease in

deaths. Policing speed limits will be notably easier and more efficient using communication

technologies.

Although the main advantage of vehicular networks is safety improvements, there are

several other benefits. Vehicular networks can help in avoiding congestion and finding better

routes by processing real time data. This in return saves both time and fuel and has significant

economic advantages.

1.2 Literature Review

Linkages between new transport technologies and analysis methods grow more strongly

all the time. The development of a communications network on the roadway infrastructure and in

the vehicles has the potential to improve transportation and quality of life in ways not imagined a

generation ago. In the near future, vehicles will communicate with one another in a cooperative

way in order to control speeds, obtain traffic information and to improve safety (eSafety).

It is predicted that the urban infrastructure will have sensors that can communicate and

interact with the vehicles, using traffic signals, traffic cameras, ramp meters, bus priority

systems, etc. V2V (vehicle-to-vehicle) is a technology designed to allow vehicles to serve as data

sensors and anonymously transmit traffic and road condition information from every major road

within the transportation network. V2I (vehicle-to-infrastructure) is the direct wireless exchange

of information between vehicles and the fixed infrastructure.

From the literature review, it appears that V2V and V2I communication systems research

has mostly focused on crash prevention, safety and traffic control. V2V is currently in active

development by General Motors, which demonstrated the system in 2006. Other automakers

working on V2V include BMW, Daimler, Honda, Mercedes and Volvo. In another development,

the Portuguese Government intends to launch an identification chip in vehicles with information

related to insurance and vehicle inspection status. It could be also used to pay tolls (green lane or

virtual tolling). Portugal is the first country to create and test such an electronic identification

system for vehicles.

Nevertheless, there is no apparent application of the proposed technology in terms of

communicating with other vehicles or receiving signals from the infrastructure or, moreover,

give real-time information to the user about the vehicle performance / fuel use / emissions. More

specifically, Santa et al. state that V2V communications are the main object of research

nowadays, because V2I approximations are already being developed as commercial solutions. In

the reliability of inter-vehicle communication in traffic stream was discussed and the information

propagation in a traffic stream via inter-vehicle communication was analyzed. According to V2V

is assumed to have a beneficial impact on traffic efficiency and road safety. Kang et al. reported

on the direction of a ubiquitous transportation system (u- Transportation, based on the concept of

ubiquitous computing technologies which is the latest emerging technology which enables

human-computer interaction in everyday objects and activities) and were more focused on the

description of traffic operation and management under u-Transportation.

More recently, Rouphail and Hu have assessed the impact and benefits of u-

Transportation network using mesoscopic modeling, and plan to evaluate both operational and

safety benefits of such a system for many types of road facilities, where the additional

information could improve the human-based traffic performance.

The closest contribution was the work of Ericsson et al. but that is not specifically

focused on V2X technologies. The assessment of the impacts of short range communication

technologies requires a micro or mesoscale approach; the macroscale approach may be too crude

for this purpose. In particular, Vehicle Specific Power (VSP) is a methodology based in on-board

emission measurements and is a function of vehicle speed, road grade, and acceleration, all of

which can be determined from simulated vehicle trajectories in a microscopic simulation model.

1.3 Objectives

The fundamental goal of this research is to assess the value of new intelligent

transportation system technologies in terms of their transportation impacts (such as traffic

congestion and emissions) in order to test the hypothesis that the appropriate use of V2V and V2I

communication technologies can positively influence the quality of urban travel, the quantity of

fuel use and emissions from mobile sources.

Changes in personal travel may change the total quantity of emissions, as well as their

spatial and temporal patterns. This research will help identify the contribution of these new

technologies as fundamental determinants of travel behavior, vehicle activity and on-road

emissions. Traffic modeling will be developed, in order to characterize the effect of V2V and

V2I information on driving pattern and route change. The modeling system will forecast energy

and emissions under each scenario and quantify the uncertainty in the emissions estimates. The

last step will be to compare scenarios and determine the statistical significance of the different

levels of emissions.

One of the major activities in the area of V2V communication is the Car-to-Car

Communication Consortium (C2C-CC) driven by major car manufacturers, aiming to generate

decentralized floating car data (FCD) communication capabilities between cars .The objective in

C2C-CC is to provide mainly broadcast services, such as broadcasting accident warnings from

car to car and roadside information from the traffic infrastructure to cars. In the field of

telecommunications the aim is to support the standardization activities driven by IEEE (WAVE

— IEEE 802.11p, IEEE 802.11 a/b/g, IEEE 1609). In the Car link project compatibility between

WAVE standards and C2C-CC work has always been an essential issue.

Figure 1.1 V2V Communication Applications Courtesy: Daimler 2009

In the United States the department of transportation is coordinating the Vehicle

Infrastructure Integration (VII) program, closely related to C2C-CC except that it is government

supported and coordinated. VII supports V2I and V2V communications in the federally allocated

5.9 GHz bandwidth, also allocated by the European Union. The communication between

vehicles and infrastructure is operated via dedicated short-range communication (DSRC) as

defined in IEEE 1609. Primary applications and targets are advisory (usually safety-related)

messaging from infrastructure to vehicles, probing anonymous data from vehicles to

infrastructure and other vehicles in a secure manner

In the Car link project the VII has been seen as a parallel and mainly mutually

compatible approach with C2C-CC work; therefore, compatibility with VII is maintained as high

as possible. The European CVIS project generates an open standards-based communication,

positioning, and networking platform for both V2V and V2I communication. Services provided

are mainly related to traffic safety and control. The communication architecture is based on the

CALM standard, bringing together different communication methods (IEEE 802.11p

networking, second/ third generation [2G/3G] Global System for Mobile Communications

[GSM]-based communication, and infrared [IR] communication) into a single architecture. The

ultimate goal of parallel solutions is to provide an “always connected” system . In Japan a similar

kind of traffic service communication platform is called VICS. VICS is a slightly older system,

the main architecture concentrating only on communication between vehicles and infrastructure.

However, the deployment rate of the solution is much higher than solutions in the United

States and Europe The European COOPERS project is also developing a communication system

for traffic environments, mainly to generate services relying on V2I communication (although

V2V communication is also supported). The goal is to provide continuous wireless

communication via DSRC technology, for services like accident and weather warnings and

traffic management. The COOPERS solution uses multiple wireless technologies like CALM-

based IR Wi-Fi communications and GSM/GPRS.

While the CVIS and COOPERS projects are mainly focused on increasing the efficiency

of the road network in Europe, the e-Safety initiative of the European Union and the EU’s

COMeSafety project are tightly focused on road safety enhancement.

While COMeSafety is acting merely as a coordinating forum for related research, the

SAFESPOT project represents a technical approach. SAFESPOT combines the sensor

information gathered from both vehicles and roadside units into traffic incident and accident

warnings

A comparison of CVIS, SAFESPOT, and COOPERS is presented in .CVIS is seen as the

core cooperative technology (with concept proof of the CALM standard), SAFESPOT as

cooperative systems to process highly critical (vehicular) tasks, and COOPERS as a road

operator interface to cooperative vehicular networking. The Car link project combines these

elements in its own approach. A similar approach of cars distributing accident warning data

V2V and even forwarding warnings car by car is presented in The LIWAS traffic warning

system is designed to provide early warnings to vehicles about adverse road conditions like

slippery road surfaces. Other approaches also exist, the most important ones being Prevent

(aiming to control vehicles directly for, e.g., braking without driver command to avoid an

accident), GST, NOW, and Sevecom. Most of the European activities in this area are more or

less related to the C2C-CC work.

Compared to the related work, the Car link approach has many similarities and even

common elements with all of the related approaches. The main advantages of Car link are the

open platform solution, the flexibility and scalability of the platform into different types of

services and capacity/ communication requirements, and operation reliability based on dual radio

communications.

2. PLATFORM & SERVICES

2.1 Design Issues

The Car link platform is designed to provide an infrastructure to a wide community of

commercial and governmental traffic and safety services. The platform itself is the key element,

but the services created for the platform also have crucial roles. On one hand, they generate

different ways to use and exploit the platform, proving its efficiency. But on the other hand, the

services are the platform’s showcase toward consumers; in order to interest consumers in

purchasing the platform (and furthermore the vehicle industry in integrating platform equipment

in vehicles), we had to have some key services interesting enough for consumers. We did not

build up an extensive package of services, but just a couple of key services to prove the

applicability, usefulness, and necessity of the platform. The (hybrid) platform, even with a low

deployment rate is in our vision a so-called killer application, raising public interest and

therefore commercial success, leading to large-scale deployment and generation of a wide

spectrum of independent services.

Figure 2.1 Operational model of local RWS and incident warning service.

The Wireless Traffic Service Platform is divided into three parts: the traffic service

central unit (TSCU), the base station network with traffic service base stations (TSBSs), and

mobile end users (MEUs) with ad hoc connectivity and (non-continuous) backbone network

connectivity. Networking procedure can be bypassed with the parallel GPRS-based

communication between the TSCU and the MEU. This channel has limited capacity but, due to

its practically complete coverage (especially in rural areas), critical emergency data is delivered

with low delay

The local RWS is derived from the Finnish Meteorological Institute’s (FMI’s) road weather

model presented in Fig. 2.2.

Figure 2.2 Schematic of the road weather model.

The effects of

Atmosphere, traffic, turbulence, ground heat

Transfer and surface heat transfer are considered,

and presented in the figure. It is a one-dimensional

Energy balance model that

Calculates vertical heat transfer in the ground

And at the ground-atmosphere interface, taking

Into account the special conditions prevailing on

the road surface and inside the ground below.

The model also accounts for the effect of traffic

Volume on the road. Output from a numerical

Weather prediction (NWP) model is typically

Used as a forcing at the upper boundary. The

Basic horizontal resolution of FMI’s present

Road weather model was 10 km, which means

-that, in principle, the model cannot resolve

Meteorological features beyond this spatial scale.

2.2Technical Specifications

Two categories of draft standards provide outlines for vehicular networks. These

standards constitute a category of IEEE standards for a special mode of operation of IEEE

802.11 for vehicular networks called Wireless Access in Vehicular Environments (WAVE).

802.11p is an extension to 802.11 Wireless LAN medium access layer (MAC) and physical layer

(PHY) specification. As of November 2006 Draft 1.3 of this standard is approved . 802.11p aims

to provide specifications needed for MAC and PHY layers for specific needs of vehicular

networks. 1609 is a family of standards which deals with issues such as management and

security of the network:

1609.1 -Resource Manager: This standard provides a resource manager for

WAVE, allowing communication between remote applications and vehicles.

1609.2 -Security Services for Applications and Management Messages

1609.3 -Networking Services: This standard addresses network layer issues in

WAVE.

1609.4 -Multi-channel Operation: This standard deals with communications

through multiple channels.

The current state of these standards is trial-use. A vehicular communication networks

which complies with the above standards supports both vehicular on-board units (OBU) and

roadside units (RSU). RSU acts similar to a wireless LAN access point and can provide

communications with infrastructure. Also, if required, RSU must be able to allocate channels to

OBUs. There is a third type of communicating nodes called Public Safety OBU (PSOBU) which

is a vehicle with capabilities of providing services normally offered by RSU. These units are

mainly utilized in police cars, fire trucks, and ambulances in emergency situations.

As mentioned before DSRC provides several channels (seven 10 MHz channels in North

America) for communications. Standards divide the channels into two categories: a control

channel and service channels. Control channel is reserved for broadcasting and coordinating

communications which generally takes place in other channels. Although DSRC devices are

allowed to switch to a service channel, they must continuously monitor the control channel.

There is no scanning and association as there is in normal 802.11. All such operations are

done via a beacon sent by RSUs in the control channel. While OBUs and RSUs are allowed to

broadcast messages in the control channels, only RSUs can send beacon messages.

In North America DSRC devices operate over seven 10 MHz channels. Two of the

channels are used solely for public safety applications which mean that they can only be used for

communications of message with a certain priority or higher.Although 802.11p and 1609 drafts

specify baselines for developing vehicular networks, many issues are not addressed yet and more

research is required.

The most popular wireless high-speed communication approaches nowadays are wireless

local area networks (WLANs), also known as Wi-Fi, 802.11 standard families. The most

common versions nowadays are the 802.11b and 802.11g

Standards operating in the 2.4 GHz bandwidth and capable of up to 54 Mb/s (.11g) or 11

Mb/s

(.11b) data speeds, respectively. The IEEE 802.16 family of standards specifies.

The air interface of both the fixed and mobile broadband wireless access (BWA) systems

for

Supporting multimedia services.

The WiMAX

System is based on these technologies. IEEE

802.16-2004 for fixed and IEEE 802.16e for

Mobile accesses are the IEEE standards that define

the current structures of the WiMAX system.

WiMAX has licensed worldwide spectrum allocations

in the 2.3 GHz, 2.5 GHz, 3.3 GHz, and

3.5 GHz frequency bands and is capable of up to

31.68 Mb/s data rates with a single antenna system

and up to 63.36 Mb/s with a multiple-antenna

system. The WiMAX is capable of supporting

fast moving users in a mesh network structure.

Systems with users moving at speeds up to 60

Km/h has been reported.

The IEEE standardization activity for the

V2V communication environment is named WAVE (IEEE 802.11p).The underlying

Technology in this standardization work is DSRC,

Presented in IEEE 1609, which is essentially

IEEE 802.11a adjusted for low-overhead operations.

The primary purpose of DSRC is to

Enhance public safety applications in order to save lives and improve traffic flow by V2V

and

Infrastructure-to-Vehicle communications. In the

United States the 75 MHz channel is allocated

for DSRC in the 5.9 GHz spectrum .

2.3 Service Specifications

The wide range of services provided by this V2V/ V2I interface is listed below:

Table 2.1 Car link services

3. ARCHITECTURE & SYSTEM REVIEW

3.1 System Description

The Car link platform structure is illustrated in Fig. 2.

1. The TSCU is on the top with connections to the

Underlying service cores, local traffic weather service,

and incident/emergency warning service. The

TSCU takes care of user management. As a central unit of the system, the TSCU

maintains the

Interdependencies of all platform elements. It also Stores all data gathered from the

platform and forwards

the appropriate data to services.

The incident/emergency warning service

Parameters are an airbag blast, a push of the emergency button in the car, car throwing,

and

the car stopping suddenly, all of them including the GPS location of the observed issue.

The RWS

Core includes a weather forecast model generating

local road weather outlook based on FMI’s operational

Measurements. This model is supplemented

with car measurements (temperature and GPS

location of observations) to complement the

weather information. The resulting local road

weather information is delivered to the TSCU,

responsible for forwarding this data to the vehicles

through the platform. Similarly, the incident/

emergency warning service collects vehicle

data to build up warnings for exact locations,

returned to the TSCU. Depending on the significance

of the warning, the TSCU selects the appropriate

path for the warning data distribution..

Figure 3.1 Operational model of local RWS and incident warning service.

The

most critical warnings (e.g., accident location) are

delivered through the GPRS connection as rapidly

as possible, while more informative warnings

can be distributed through the BSs

The network of TSBSs below the TSCU (Fig.2.

1) mainly act as data transmitters from the

TSCU to the MEUs and vice versa. The TSBS

also collects weather data itself and delivers it to the TSCU.

The MEUs in vehicles are the users of the

Car link platform, gathering data along the roads

they are driving, delivering it up to the TSCU

and the underlying services, and, finally, consuming

Weather and warning information derived

from the vehicle-based data. The parameters

gathered from the vehicle are the temperatures,

car throwing indicator, car sudden braking indicator,

airbag blast notification, push of emergency

Button notification and the GPS location for

each data source. The WLAN/WiMAX and

GPRS interfaces are used for communication

With the TSBSs and TSCU.

3.2 Technical Requirements

The communication between the TSCU and

TSBS occurs straightforwardly in the fixed network,

posing no challenges. In the wireless communication

between the TSBS and the MEUs,

We do not require handoff of the connection, but

the traffic speed (up to 100 km/h in our scenario)

generates an extremely challenging element to

our platform.

However, ad hoc networking with

handoff and seamless continuation of communication

are important issues required in the final

operative system. The most popular solution for

Wireless communication is the Wi-Fi system,

which is based on the IEEE 802.11 standard family.

The latest version of the standard is IEEE

802.11g, capable of 54 Mb/s data speed and with

a coverage up to at least 100 m (maximum range

allowing only 1 Mb/s data speed). The use of this

system at traffic speeds is a challenging task. The

time a vehicle stays in the area of the base station

is rather short for initiating the connection

and carrying out data exchange. Also, IEEE

802.11g with carrier sense multiple access with

collision avoidance (CSMA/CA) is not especially

tailored for the quick connection creation of

high-speed nodes.

The 802.11 standardization

forum has noted that existing 802.11 standards

(a,b,g) are not optimal for fast nodes and is tackling

the issue of vehicular communication, especially

in the 802.11p standardization work, based

on the IEEE 1609 standard family. However,

during our project pilot definition components

were not yet available. In our research Wi-Fi

based on IEEE 802.11g stands for an existing

communication product, while IEEE 802.11p

represents the ultimate future solution, to be

adapted as soon as available.

In this we have analyzed 802.11g in the

simulations developed in the NS-2 tool, in parallel

with field measurements of Wi-Fi communication

and pilot system analysis.

One step further is wireless ad hoc communication

between vehicles. The technical challenges

here are basically the same as in BS-oriented Wi-

Fi communication except that the encounter

speed is doubled (and the communication time

halved) because in the extreme situation both

counterparts are moving in opposite directions.

Hence, it is hard to enable full-scale ad hoc networking.

In order to ensure platform operability

we require at this point that the MEUs are only

able to exchange their packed up-to-date data in

an encounter, instead of true ad hoc networking.

This way we extend the TSBS range by implementing

one hop in the ad hoc network, from the

vehicle receiving the TSBS transmission to a

vehicle out of TSBS range.

Finally, we need to ensure that the most crucial

data will also be exchanged in the platform

without any delay when there are no TSBSs

nearby. For this purpose we use a standard

GPRS data service. This solution guarantees the

reliability required in this particular scenario,

even if the capacity may be too low for all platform

Services.

4. PERFORMANCE ANALYSIS

4.1 Performance

The platform’s operability has been analyzed in

simulations with the NS-2 tool and parallel field

measurements. The focus has been on rural

areas with low BS density, since that is the challenging

area in the deployment phase. The maximum

throughput is defined to 54 Mb/s, based on

IEEE 802.11g. Omnidirectional antennas with

500 m range are used throughout the simulations,

and all vehicles and BSs have similar (single)

transceiver units.

We have defined two main simulation scenarios

in the road containing four BSs with 1 km

distance between each other. In one one-way

traffic scenario, four or eight vehicles are traveling

at 100 km/h speed through the road in one

direction, while in the bidirectional traffic scenario

there are two sets of either four or eight

vehicles. The distances between consecutive vehicles were fixed to 100 m. The

simulation system is a combination of V2I and V2V; we have the data source in the fixed

network, delivering

the data to the vehicles through BSs (V2I), and vehicles forward the data V2V to the

destination

node.

The main results of the simulations are

gathered in Table 4.1. It can be seen that the connection

availability percentage during the simulation

is slightly improved when the amount of nodes is increased, due to additional vehicles’

capability to forward data from vehicle to vehicle.

The price of improved connectivity is

decreased throughput as the packet forwarding

also uses the precious data capacity.

Opposite to

the former analysis, in the case of (bidirectional)

8 + 8 vehicles, the average connection availability

decreases compared to the case of eight one way

vehicles. The throughput saturates as 54

Mb/s data channel capacity is not sufficient to

support large amounts of simultaneous connections

with high data volumes. Therefore, even if

connection availability is increased due to forwarding

nodes, at a certain point the capacity

limitations will ultimately also have a negative

effect on connectivity. The supporting field measurements

tested the data throughput limits of

IEEE 802.11g when a vehicle is passing by either

the BS (V2I) or another vehicle moving at the

same speed (V2V).

The field test goal was to

prove the simulated conditions for a simple case,

while simulations themselves emulate the scenario

with more vehicles, BSs, and traffic in general.

The measurements showed capacities up to

4.98 Mb/s in V2I communications and 3.59 Mb/s

in V2V after the connection was established.

Table 4.1 Main results of the simulations.

Therefore, the performance decrease due to fastmoving vehicles is not very dramatic, and

underlying assumptions built into the ns-2 simulation

environment (operation with low-mobility nodes)

remain valid. The connection establishment time

increased and connection uptime decreased

when the vehicle speed was increased. The

appropriate performance was achieved with all

speeds used, varying between 60 km/h and 104

km/h, respectively. We defined the appropriate

performance in our case as reached when the set

of pilot/developed services can be provided in

such a way that a system user receives data fast

enough to exploit the safety benefits.

The ultimate test of the platform was conducted in the pilot platform, consisting of

two

vehicles, two TSBSs, and a TSCU, using IEEE

802.11g Wi-Fi and GPRS communications to

provide the pilot system services listed in Table 4.

1. The main data channel was Wi-Fi, but due to

extremely low density of BSs, we relied on GPRS

data communication most of the time. For communication

between vehicles we used GPRS

communication only, as we were concentrating on showing pilot services operability in

general.

The specific pilot services were tested one by one, and were found to operate adequately.

We

defined service operation as adequate when:

The service response to “impulse” (e.g., vehicle

throwing is noted when a driver turns the

wheel roughly) is reliable (at least 90 percent

success rate expected).Service data (incident/accident warning, weather data) is delivered

to all vehicles/devices in

the network within 5 s.

Table 4.2 Estimated effect of Carlink pilot system to the number of fatal accidents based on

accident statistics in Finland

Wi-Fi communication clearly sped up data delivery

to “nearly instant” response. With GPRS, it

took several seconds from initiating a warning

condition to see the warning on the screen; and

for the example of danger in a chain accident of

vehicles, the delay is too long. In the operational

system on a crowded highway, the delay must be

limited to“less than a second in order to avoid

(the main part of) chain accidents. With our

pilot relying on GPRS most of the time this is

not possible, but in the expected final system

relying on a dense BS network and Wi-Fi-based

ad hoc networking between vehicles, this is the

ultimate objective.

As a final statement, the pilot system provided

satisfactory performance (based on our adequate

service operation definition above) in its

limited scale. Based on the pilot system operability,

and assuming a dense network of TSBSs in

use, we estimated the effect of our pilot system

on traffic fatalities. We used the statistics of

fatalities in Finland for 2007, and estimated the

effect of our services on each type of traffic

fatality.

As a result, based on the estimation

shown in Table 4.2, we have estimated a 10–30

percent decrease of lives lost in traffic, which at

its best would have been almost 100 persons in

Finland for 2007. We find this result truly meaningful

in the area of improving traffic safety.Obviously, only the operative final system will

eventually prove the quality of the estimations.

Figure 4.1 simulation results for various no. of nodes

5. APPLICATIONS

5.1 Applications

Vehicular communication networks will provide a wide range of applications with

different characteristics. As these networks have not yet been implemented, a list of such

applications is speculative and apt to change in the future (However safety, which is the main

purpose of these networks, will most probably remain the most important applications).

Furthermore some of these applications require technologies that are not available now.

Ultimately we would like to delegate the full handling control of our cars to the vehicles

themselves; somewhat similar to autopilot. The classifications of applications is not unique and

many institutions involved in intelligent transportation systems propose their own set of

applications and classifications. We classify the possible applications in the following categories:

Safety

Providing safety is the primary objective of vehicular communication networks. Vehicles

who discover an imminent danger such as an obstacle inform others. Electronic sensors in each

car can detect abrupt changes in path or speed and send an appropriate message to neighbors.

Vehicles can notify close vehicles of the direction they are taking so the drivers can make better

decisions; a more advanced version of turn signals. In more advanced systems, at intersections

the system can decide which vehicle has the right to pass first and alert all the drivers. Some of

the immediate applications are:

Warnings on entering intersections.

Warnings on departing the highways

Obstacle discovery

Sudden halts warnings

Reporting accidents

Lane change warnings

Traffic management

Traffic management is utilized by authorities to ease traffic flow and provide a real time

response to congestions. Authorities may change traffic rules according to a specific situation

such as hot pursuits and bad weather. Applications include:

Variable speed limits

Adaptable traffic lights

Accommodating ambulances, fire trucks, and police cars

Driver assistance systems

Roadside units can provide drivers with information which help them in controlling the

vehicle. Even in the absence of RSUs, small transmitters may be able to issue warnings such as

bridge or tunnel height or gate width:

Parking a vehicle

Cruise control

Lane keeping assistance

Road sign recognition

Policing and enforcement

Police can use vehicular communications in several ways:

Surveillance

Speed limit warnings

Restricted entries

Pull-over commands

Pricing and payments

Electronic payment results in convenient payments and avoiding congestions caused by

toll collection and makes pricing more manageable. For instance tolls can be variable for

weekdays and weekends and during rush hours:

Toll collecting

Parking payments

Direction and route optimization

For reaching a destination there are usually many different routes. By collecting relevant

information system can find the best paths in terms of travel time, expenses (such as toll and

fuel), …

Travel-related information

In an unfamiliar town drivers may be assisted to find relevant information about available

services:

Maps

Business locations

Car services

Gas stations

General information services

As with many other communication networks, vehicular networks can be used to obtain

various content and services (not directly related to traveling). In this respect there are numerous

applications. In the case that wireless vehicular networks are integrated to the Internet, which is

very likely, virtually every application that is currently used in the Internet will find its way to

vehicular networks as well. However applications with lower bandwidth requirements are likely

to become widespread sooner.

Some applications can be:

Web surfing

File downloads

Email

Gaming

Automated highways

Automated highway is not yet realizable but nevertheless is an important application. In

these highways the vehicles are able to cruise without help of their drivers. This is done by

cooperation between vehicles. For example each vehicle knows the speed and direction of travel

of its neighboring vehicles through communication with them. The status is updated frequently;

therefore each vehicle can predict the future up to some necessary time and is able to make

appropriate decisions in appropriate time. Because automated highways are not limited by

human response time, much higher speeds will be possible. This application is virtually

impossible without utilizing vehicular networks.

6. FUTURE SCOPE & CHALLENGES

This project can be extended further to make accident free roads and automated

teller vehicles. By extending this project the traffic diversion will be feasible task which ensures

less inconvenience for the public. The remote location of the vehicles becomes easier. The voice

calling protocols from the vehicles can be replaced with Voice over IP (VoIP) protocol which is

fast efficient and the most reliable.

However this project has many challenges. The vehicles can be very easily tracked

so the target becomes simple for anti social elements. The spectrum of data communications will

also be challenging in still developing countries like India. The bandwidth and signal strengths of

the spectrum in rural areas are still poor.

7. CONCLUSION

The Car link concept of a

Hybrid wireless traffic service platform between

cars. The ultimate goal was to create an intelligent

Communication platform for vehicles where

they can deliver their own observations of traffic

and weather conditions to the platform core.

This information is delivered back to the vehicles

as analyzed (and forecast) information about

road weather conditions and immediate incident

Warnings. Compared to competitive solutions presented in related work, the Car link

solution

Showcases a true bidirectional communication entity for a variety of traffic and safety

services.

It has been shown that Car link presents a substantial

Candidate solution for a comprehensive

Vehicular communication entity, with clear potential

to decrease accidents and lives lost in traffic.

8. REFERENCES

1. T. Sukuvaara et al., “Wireless Traffic Service Communication Platform for Cars,”

2nd IEEE Wksp. Automotive Networking and Applications, Washington, DC., Nov.30,

2007

2. T. Sukuvaara et al., “Advanced Wireless Vehicle Networking Platform for Real-Time

Incident and Weather Information,” 15TH World Congress on ITS, New York, Nov.

16–20, 2008.

3. IEEE 802.11p, “Wireless Access for Vehicular Environments,” draft standard.

4. IEEE P1609.1, “IEEE Trial-Use Standard for Wireless Access in Vehicular

Environments (WAVE) {Resource Manager},; IEEE P1609.3, “IEEE Trial-Use

Standard for Wireless Access in Vehicular Environments (WAVE) {Networking

Services}.”

Web References

www.wikipedia.org

www.google.co.in

www.ieeexplore.org