Journal of Transportation Technologies, 2011, 1, 132-137
doi:10.4236/jtts.2011.14017 Published Online October 2011 (http://www.SciRP.org/journal/jtts)
Intelligent Transportation Systems Using Short
Range W ir eless Technologies
Razi Iqbal, Kenichi Yukimatsu
Department of C omput er Science & Enginee ri ng,Graduate School of
Engineering and Resource Science, Akita University, Akita, Japan
Received July 2, 2011; revised August 10, 2011; accepted August 30, 2011
Abstract
In this paper, we propose using ZigBee for Intelligent Transportation System (ITS). Most of the accidents
these days are caused because of drivers not knowing the upcoming traffic hurdles like curves, traffic signals,
railway lines and etc. If drivers come to know about the upcoming signals, curves, and railways lines etc the
accidents can be avoided. The aim is to provide drivers with intelligent roads so that they can receive the in-
formation about the curves and the traffic signals ahead. After receiving the information about the signals
ahead, drivers will be careful; this will help avoid the road accidents. Many researches are taking place in the
world in the field of ITS and many useful systems are also built but no system is built using this remarkable
ZigBee technology. ZigBee is low cost as compared to other short range wireless technologies which will
help reduce the total cost of the system, enabling this system to be deployed in developing countries as well.
Keywords: ITS, Short Range Wireless Technologies, Wi-Fi, GPS
1. Introduction
Most of the accidents on the roads occur today because
drivers are not aware of upcoming traffic hurdles like
traffic signals, curves and railway lines etc. Similarly in
mountainous areas where there is lots of rain and snow
throughout the year, driving is a tough job. In order to
make driving on roads easy, an efficient system is re-
quired which informs drivers about upcoming traffic
hurdle before a safe distance so that drivers can be care-
ful. There are many researches going on in the field of
ITS and already many systems are available but these
systems are very expensive which make these systems
very difficult to install in developing countries [1,2].
Furthermore these systems require high Power to operate
which make these systems difficult to install in areas
where there is no power available [2].
This resear ch bring s an id ea of u sing shor t r ange w ir eless
technology “ZigBee” in Intelligent Transportation Systems.
ZigBee is inexpensive which reduces the total cost of the
system [3]. Similarly its low power consumption makes it
useable in areas where there is no power available.
2. Objective
The main objective of the research is to provide drivers
with intelligent traffic system which will help by provid-
ing important info rmation about the traffic while th ey are
on the road. In the snowy areas drivers are unable to see
the traffic signals when it’s snowing and get an idea
about the curves and traffic signals when they are at it
which results in road accidents [4]. So in order to over-
come this difficulty the idea is to provide the in formation
about the upcoming traffic signal before a safer distance
so that drivers are careful.
The core of the research is to provide ITS solution us-
ing ZigBee [3]. So most of the experiments are con-
ducted with the ZigBee apparatus and using the RSSI
(Received Signal Strength Indicator) value received from
Host to Sensor. The purpose of using ZigBee for ITS is
that at mountains there can be problem of electricity and
at those places installing ITS can be really expensive. In
order to provide ITS at those places we need some tech-
nology that saves power and price. ZigBee is best for this
purpose and fulfils these needs efficiently.
3. System Description
Figure 1 illustrates the concept of this research. Because
of the weather conditions most of the times, traffic hur-
dles become very dangerous and cause road accidents e.g.

133 R. IQBAL ET AL.
slippery at curve or invisibility of traffic signals due to
fog or heavy snow. In such conditions drivers get aware
of these traffic hurdles when they are at it and won’t be
able to stop the car which results in accidents. This re-
search will emphasize on warning (informing) drivers of
upcoming traffic hurdles before actually reach- ing them
[5].
The above diagram shows a traffic system which in-
forms drivers about the traffic hurdles. On each traffic
hurdle a ZigBee Sensor is installed and each car is
equipped with a ZigBee Host. Whenever car reaches the
range of the ZigBee Sensor (for this research we consid-
ered this range to be 100 m), the communication between
the ZigBee Sensor and Host starts, the ZigBee Sensor
sends the signal (in the form of bits) to the ZigBee Host
informing about the type of hurdle ahead along with the
distance to the hurdle. The ZigBee host after receiving
this information will display this in formation on a screen
to driver. Driver then can take appropriate action after
getting informed [3].
Below are the traffic hurdles we are considering in this
research;
1) Road stops.
2) Railway tracks (Railways lines).
3) No Entry roads.
4) Traffic signals.
5) Curves.
6) Brake indicators
No. 6 in above listing is a sp ecial case. For this case to
work the cars have to communicate with each other so
that they get notified about the brakes applied by the car
in front. This case is more of a future plan which we are
planning to research and not covered in this research
paper.
4. Flow of Information
In this system a ZigBee sensor is installed at each traffic
hurdle that contains all the information about that hurdle
e.g. Hurdle ID, Distance from ZigBee Host etc. Each car
in this system is equipp ed with ZigBee Host. As soon as
car enters the communication range of the traffic hurdle,
ZigBee Host in the car starts communicating with Zig-
Bee Sensor at the traffic hurdle [5,6].
Figure 2 shows the information flow between the car
and the traffic hurdle, in this case the Traffic Signal. The
numbers 1~5 are described be l ow;
1).Car (ZigBee Host in the Car) sends its ID to the
Sensor at Traffic Signal.
2).Sensor acknowledges the ID.
3).Car asks for the information about the upcoming
traffic hurdle.
4).Sensor sends the information about the traffic hurdle.
Figure 1. ITS using ZigBee as a communication Medium.
Figure 2. Flow of information between Car and Traffic
Signal.
Figure 3. Flow chart depiction of Figure 2.
5).Acknowledges the information received from traffic
hurdle.
Figure 3 is an easy to understand flow chart depiction
of Figure 2.
5. Why ZigBee?
ZigBee is a short range wireless technology from IEEE
802.15.4 family. ZigBee is low power and low cost as

R. IQBAL ET AL.
134
compared to other short range wireless technologies of
its class. Below is ZigBee comparison with other short
range wireless technologies [3].
As shown in Table 1 ZigBee is low power and very
inexpensive as compared to other short range wireless
technologies. ZigBee devices can work for years without
worrying about replacing batteries, which makes it an
excellent choice to be used in mountainous areas where
power is a major concern.
Below are the major reasons why ZigBee is consid-
ered for such system;
1).ZigBee is Low cost
2).ZigBee is inexpensive
3).Data rate is enough to transfer information between
Car and the Hurdle.
4).ZigBee is not much affected by the signals of other
short range wireless technologies.
6. Conducted Experiments
Different experiments were performed to check whether
ZigBee is suited for such systems or not. There are dif-
ferent researches going on in which ZigBee is used as
In-Vehicle communication medium but using ZigBee as
Vehicle-to-Vehicle or Vehicle-to-Infrastructure is a to-
tally new concept. Below are the conditions in which
experiments were performed;
1).Maximum distance between ZigBee Host and Sen-
sor is 100m.
2).A suitable height of 2 m is used for ZigBee Host
and Sensor.
3).Experiments are conducted against different Speeds
of Vehicle (10~60km/h).
4).Two set of experiments were conducting to check
ZigBee suitability in Intelligent Transportation Systems
[6,7].
 Experiments to check RSSI (Received Signal
Strength Indicator) value from ZigBee Host to Zig-
Bee Sensor.
 Experiments to check Data Transfer between ZigBee
Host and ZigBee Sensor.
Below are the details of experiments along with col-
lected data.
6.1. Experiments for RSSI
Two different experiments were conducted to check
RSSI value between ZigBee Host and ZigBee Sensor.
The value of RSSI is calculated in dBm. The communi-
cation between Host and Sensor is ideal if RSSI value is
0, but that is not possible because of different factors
affecting the value, like noise, air elements and weather
etc.
1).ZigBee communication on straight road with clear
line of sight (LoS).
Table 2 shows the data collected for Experiment 1, for
checking RSSI value between Host and Sensor on
straight roads with clear LoS [8]. For each speed of car,
RSSI value is checked twice and then average RSSI is
calculated. Data in Table 2 shows that speed of vehicle
has almost no effect on RSSI value between the Host and
the Sensor.
Figure 4. ZigBee Communication on straight road with LoS.
Table 1. Wireless Technologies Comparison.
Wireless Technologies Comparison
Proerty
Wi-Fi Bluetooth ZigBee
Data Rate 11Mbps 1Mbps 250kbps
Nodes 20 - 250 7 65536
Range 100m 10m 30~100m
Power High power Medium Power Low Power
Cost Very high $10 ~ 15 As low as $3
Table 2. RSSI on Straight Road with LoS.
RSSI on Straight Road with clear LoS
Car SpeedRSSI (1)
dBm RSSI(2) dBm RSSI (Avg) dBm
10 km/h –58 –57 –57.5
20 km/h –58 –58 –58
30 km/h –58 –57 –57.5
40 km/h –63 –62 –62.5
50 km/h –58 –58 –58
60 km/h –57 –58 –57.5

135 R. IQBAL ET AL.
2).ZigBee communication on curve with clear line of
sight.
Table 3 shows the data collected for Experiment 2, for
checking RSSI value between Host and Sensor on curves
with clear LoS. For each speed of car, RSSI value is
checked twice and then average RSSI is calculated. On
curves mostly the cars are driven slowly so experiments
are conducted against the speed of car up to 30 km/h.
The data in Table 3 shows that even in the case of
curve, the speed of the vehicle has no significant effect
on RSSI value between the Host and the Senor.
6.2. Experiments for Data Transfer
Three types of experiments were conducted to check the
eligibility of ZigBee for ITS. Experiments are conducted
using Data Transfer sequence shown in Figure 2. The
arrangement of the experiments for Data Transfer is
similar to that of experiments for RSSI. ZigBee Host is
installed inside the car and ZigBee Sensor is installed at
the traffic hurdle, but this time Data Transfer rate be-
tween Host and Sensor are examined [9].
1).Data Transfer on straight road with cl ear line of sight.
Table 4 shows the data collected for Data Transfer
experiments. The distance is the distance between the
Host and the Sensor. The data (max. of 7 bytes) is sent
from Host and received at Sensor vice versa. If all the
data sent from Host is received at Sensor and vice versa,
the error percentage is 0.00% as shown in above table
[4,9].
2).Data Transfer on curves with trees as hurdles (No
line of sight).
Table 5 shows the data which is still quite encourag-
ing although there are a few errors, but the average
shows that every 6 times data is sent 4.67 times it is re-
ceived. If the data is received even only once the com-
munication between the Host and the Sensor can be done
easily and the information about the upcoming traffic
hurdle can be easily transferred to the car [4].
1).Data Transfer on curves with Buildings as hurdles
(No line of sight).
Figure 5. ZigBee Communication on curve with LoS.
Figure 6. Data Transfer on straight road with clear LoS.
Figure7. Data Transfer with no LoS (Trees as Hurdle).
Figure 8. Data Transfer with no LoS (Building as hurdle).
Table 3. RSSI on curves with LoS.
RSSI on curves with clear LoS
Car
Speed RSSI (1) dBm RSSI (2) dBm RSSI (Avg) dBm
10 km/h –54 –56 –55
20 km/h –55 –55 –55
30 km/h –58 –57 –57.5
Table 4. Data transfer on straight road with LoS.
Data Transfer on straight Road with clear LoS
Distance
No. of times sent No. of times
received Error (%)
100 m 6 6 0.00%
100 m 6 6 0.00%
100 m 6 6 0.00%

R. IQBAL ET AL.
136
Table 6 shows the Data Transfer between the Host
and the Sensor with building as a hurdle between them.
In this case two types of experiments were conducted.
Experiments with 100 m range showed higher error per-
centage and experiments with 50 m range showed lesser
error percentage.
The data in Table 6 shows although the data transfer
is done in case of buildings as hurdle but there is high
percentage of error.
If we consider the distance of 50 m, then error rate is
less but that will also reduce the “Safe distance” before
which driver gets to know about the upcoming traffic
hurdle, in this case 50 m [2].
Table 5. Data Transfer on curves with trees as hu rdle.
Data Transfer on curve with no LoS
Distance
No. of times sent No. of times
received Error (%)
100 m 6 6 0.00%
100 m 6 5 16.67%
100 m 6 5 16.67%
100 m 6 3 50.00%
100 m 6 5 16.67%
100 m 6 4 33.33%
Average 6 4.67 22.22%
Table 6. Data Transfer on curves with b uilding as hu rdle.
Data Transfer on curve with no LoS
Distance
No. of times sent No. of times
received Error (%)
100 m 6 3 50.00%
100 m 6 2 66.67%
100 6 1 83.33%
Average 6 2 66.67%
50 m 6 5 16.67%
50 m 6 4 33.33%
50 m 6 6 00.00%
Average 6 5 16.67%
7. Experiment Outcome
7.1. Outcome for RSSI Experiments
Below are the conclusions from the experiments done to
check the RSSI value for Host and the Sensor;
1).Larger the distance between the Host the Sensor,
the smaller the value of RSSI and difficult it is to com-
municate.
2).Vehicle speed has no significant effect on RSSI value.
3).Weather has no significant effect on RS SI value.
4).With clear line of sight it is easy for Host and Sen-
sor to communicate with each other.
5).Distance is not the only factor to affect the RSSI
value, noise, air pollution and other factors in the air can
also affect RSSI value.
7.2. Outcome for Data Transfer Experiments
Below are the conclusions from the experiments done to
check the Data Transfer between the Host and the Sen-
sor;
1).Larger the distance between the Host and the Sen-
sor, difficult it is to send/receive the data.
2).The bigger and denser the hurdles between the Host
and the Sensor, the more the error rate.
3).The straighter the road, the better it is to
send/receive data between the Host and the Sensor.
4).Speed of case has no significant effect on data
transfer r a t e .
5).Weather has no significant effect on data transfer
rate.
8. Proposed Solutions to the Problems
Experimental data shows there is problem in communi-
cation between ZigBee Host and Sensor if there are hur-
dles like trees or buildings. To overcome this problem
ZigBee relays can be used which can increase the range
of communication. The arrangement can be to put a
ZigBee relay between ZigBee Host and the ZigBee sen-
sor which will help transfer data from Host to Sensor and
vice versa.
Different experiments using ZigBee relays are still
under way and are not c o vered in this pa per [2,3].
9. Summary
Intelligent Transportation Systems using short range
wireless technologies as a communication medium is an
effort to make driving easy. This research is based on a
concept that drivers get to know about the upcoming
traffic hurdles like traffic signals, curves, railway lines

R. IQBAL ET AL.
137
etc before actually reaching at them. This will avoid ac-
cidents on road which are caused by sudden confronta-
tion with traffi c hurdles. Similarly th is system can be very
helpful in mountainous areas where there is snow and fog
and drivers are actually unaware of upcoming traffic hur-
dles. ZigBee is a short range wireless technology used in
this research because it’s very inexpensive and consumes
very low power as compared to its other peer short ranger
wireless technologies like Bluetooth and Wi-Fi. Since this
system is more important for mountainous areas where
there is no power in some cases, ZigBee will help with its
low power consuming attribute. Although ZigBee is a
short range wireless technology but it provides enough
range to transfer data from car to traffic hurdles and vice
versa. Because of its low cost, this system can be used in
developing coun- trie s as well.
Conducted experiments show some encouraging re-
sults, which show that ZigBee with its low power, low
cost and enough data transfer rate is a good choice for
Intelligent Transportation Systems of this class.
10. Acknowledgements
This work is supported by the Strategic Information and
Communication R&D Promot io n Pr ogr amme 1 023020 05
from the Japanese Ministry of Internal Affairs and Com-
munications.
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