Protocol Design and Implementation of Vehicular Ad-hoc Networks

transmit an E frame in ch1 where is will be
received and forwarded by nearby vehicles. It will
also transmit an E frame in ch2 intended for the
responding unit of the station. After transmitting,
the VM will start a timer for 25ms and wait for an
ACK from the RU. If it is not received within this
time, it will continue to transmit the E frame until
it receives an ack.
VI. EXPERIMENTAL VERIFICATION
The architectural and hardware design we
have proposed in this paper was implemented
using three vehicles and two roadside stations.
The vehicular modules were strapped onto
remote-controlled cars and the roadside stations
simply placed on the ground. One major difficulty
was the initial configuration of the RFM12
module because of much of the available data
being incorrect and the official programming
guide [8] containing many errors. However, this
was resolved after extensive troubleshooting. We
first strove to establish wireless contact between
the modules and this was done by generating and
transmitting a random number sequence using any
one module, and receiving and displaying the
numbers at the other module. With this working
as desired, we were satisfied that the FM module
was configured correctly, meaning we could now
proceed with testing the protocol.
The following tests determine the working of
the protocol: (a) A vehicle comes into range of an
RM. VM-disp1 on the vehicle will immediately
show the sID of the station and VM-disp2 will
show the vehicle count (indicating the amount of
congestion). This is the normal state of the
displays of a vehicle. (b) A vehicle goes out of
range of an RM. An RM detects the leaving of a
vehicle within 5 seconds of it leaving, and this is
shown by the change in RM-disp2, which displays
the vehicle count. (c) A vehicle has an accident.
VM-disp2 of the affected vehicle will display the
letter ‘E’. RM-disp1 will display the vID of the
vehicle. VM-disp1 and VM-disp2 of nearby
vehicles will show ‘E’ and the vID of the affected
vehicle respectively for 5 seconds before reverting
back to the normal state, described above. This
effect spreads onto vehicles farther away as the E
frame propagates.
There was no need for an error checking
scheme as the data is refreshed regularly. Our
prototype system makes an effective platform for
723
further enhancements in future, for example, by
expanding the frame size and increasing data
volume to support more features. The security
aspect was also neglected in this preliminary
model, making the system vulnerable to attacks
by malicious vehicles, possibly jamming the
roadside station. However, further developments
can make the system impervious to such attacks.
VII. REFERENCES
[1] A. Shastri, R. Dadhich, Ramesh C. Poonia.
“Performance Analysis of On-Demand
Routing Protocols for Vehicular Ad-hoc
Networks,” International Journal of Wireless
& Mobile Networks (IJWMN) Vol. 3, No. 4,
pages 103-111, August 2011.
[2] Yue Liu, Jun Bi and Ju Yang. "Research on
Vehicular Ad Hoc Networks," Control and
Decision Conference. CCDC '09. Chinese,
pp.4430-4435, June 2009.
[3] Ghassan M. T. Abdalla, Mosa Ali Abu-
Rgheff and Sidi Mohammed Senousi.
“Current Trends in Vehicular Ad Hoc
Networks,” Ubiquitous Computing and
Communication Journal, 1-9 (2007).
[4] Bilal Munir Mughal, Asif Ali Wagan and
Halabi Hasbullah. “Efficient congestion
control in VANET for safety messaging," In:
4th International Symposium on Information
Technology (ITSim'10), pages 654-659, June
2010.
[5] Lochert, C.; Hartenstein, H.; Tian, J.; Fussler,
H.; Hermann, D.; Mauve, M.; , "A routing
strategy for vehicular ad hoc networks in city
environments," Intelligent Vehicles
Symposium. Proceedings. IEEE, pp.156- 161,
June 2003.
[6] C2C-CC: CAR 2 CAR Communication
Consortium. http://www.car-to-car.org/
[7] Sumaya Iqbal, Shihabur Rahman Chowdhury,
Chowdhury Syeed Hyder, Athanasios V.
Vasilakos and Cheng-Xiang Wang.
“Vehicular Communication: Protocol Design,
Testbed Implementation and Performance
Analysis,” In IWCMC '09 Proceedings of the
2009 International Conference on Wireless
Communications and Mobile Computing:
Connecting the World Wirelessly, pages 410-
415. 2009.
[8] Hope Microelectronics CO.,LTD. RF12
Programming guide, 2006.