International Journal of Engineering Trends and Technology (IJETT) – Volume 15 Number 6 – Sep 2014
Geo Based Vehicular Adhoc Network Protocol and
Dynamic Slot Allocation
Sekhar Dunna1 Tatapudi Prabhakara Rao2
1
Final Year M.Tech Student, Dept. of CSE, Aditya Institute of Technology and Management(AITAM), Tekkali, Srikakulam,
Andhra Pradesh
2
Sr.Asst.Professor, Dept. of CSE, Aditya Institute of Technology and Management(AITAM), Tekkali, Srikakulam, Andhra
Pradesh
Abstract:- An Medium access control (MAC) implementation in
Vehicular adhoc network is still an important research issue
because it is a vehicle traffic optimization approach. Even though
various available with traditional approaches they are not optimal
because of vulnerabilities during the broadcasting, we need an
efficient and a novel broadcasting mechanism for vehicular
adhoc networks, road side units which periodically broadcasts the
signals either wired or wireless. We are optimizing each vehicle
decides whether or not it is allowed to access the channel based
on its location on the road in efficient manner. Our experimental
results shows broadcasting of packets based on the Service
request, broadcast range and priority and efficiently handles
during the collision of the nodes when they are within range and
same transmission range of packets and time.
Index terms: On Board Unit, Road Side Unit, Broadcasting,
Vehicular adhoc network.
I.INTRODUCTION
There is a rapid increase of vehicle along with
millions of population and increase of death cases every
year even though various traffic rules are set for safety of
people. Vehicular Adhoc Networks (VANET) should upon
implementation collect and distribute safety information to
massively reduce the number of accidents by warning
drivers about the danger before they actually face it. Such
networks comprise of sensors and On Board Units
(OBU)installed in the car as well as Road Side Units(RSU)
and the data collected from the sensors on the vehicles can
be displayed to the driver broadcasted to other vehicles
depending on its nature and importance and the RSU
distributes this data along with data from road sensors
weather forecasting centers, other traffic control centers
and other to the vehicles and also provides commercial
services such as parking space booking along with Internet
access and gas payment and the network makes extensive
use of wireless communications to achieve its goals but
although wireless communications reached a level of
maturity and a lot more is required to implement such a
complex system. Most available wireless systems rely on a
base station for synchronization and other services however
using this approach means covering all roads with such
infrastructure which is impractically too expensive.
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Adhoc networks have been studied for some time
but VANET will form the biggest adhoc network ever
implemented, therefore issues of stability, scalability and
reliability are main concern VANET therefore is not an
architectural network and not an adhoc network but a
combination of both of this unique characteristic combined
with high speed nodes complicates the design of the
network [1][4][5].
Most VANET applications consider the availability
ofreal-time updated position information. They differ,
however, on the localization accuracy required in order to
beable to function properly. For instance, some
applications can work with inaccurate localization
information in which computed positions can have errors
from 10 to 20 or 30 m, while other applications, especially
critical safety applications, require more accurate and
reliable localization systems with sub-meter precision. In
this section, we divide VANET applications into three
main groups according totheir localization requirements
and show how position information is used by these
protocols and algorithms [2][7].
Dedicated Short Range Communication (DSRC)
refers to the use of vehicle-to-vehicle and vehicle-toinfrastructure communications to improve road safety and
increase transportation efficiency. Among the many
candidate applications, cooperative collision avoidance
(CCA) has attracted considerable interest in the research
community as it can significantly improve road safety. In
CCA, moving cars form a network to wirelessly
communicate and warn each other of changing conditions
or dangers ahead on the road to avoid accidents.This
application requires timely communication of safety
messages between vehicles with high reliability, and the
medium access control (MAC) protocol has a vital role to
play. VariousMAC protocols have been proposed for
vehicle-to-vehicle communications in the research
literature [3][8].
II. RELATED WORK
The VANET under consideration consists of a set
of RSUsand a set of vehicles moving in opposite directions
on two way vehicle traffic roads [6]. A vehicle is said to be
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International Journal of Engineering Trends and Technology (IJETT) – Volume 15 Number 6 – Sep 2014
moving in aleft (right) direction if it is currently heading to
anydirection from north/south to west/east Based on this
definition, if two vehicles are moving inopposite directions
on a two-way road, it is guaranteed that one vehicle is
moving in a left direction while the othervehicle is moving
in a right one.The VANET has one control channel,
denoted by c0, and M service channels, denoted by c1,c2, . .
. ,cM. Channel c0 isused for transmission of two kinds of
information: high priority short applications (such as
periodic or event driven safety messages) and control
information required for the nodes to determine which time
slots they should access on channel ci, i= 0,. . .,M. The M
service channels are used for transmission of safety or non
safety related application messages [7][9].
z
w
x
y
x
Collision
Fig1 : Merging Collision caused by Node mobility
A provider is a node which announces on channel
c0 for a service offered on a specific service channel, while
a user is a node which receives the announcement for a
service and decides to make use of this service. Each node
has two transceivers: Transceiver 1 is always tuned to
channel c0, while transceiver 2 can be tuned to any service
channel ci; i = 1, . . .,M. It is assumed that the transmission
power levels on all channels are fixed and known to all
nodes. All channels are symmetric, in the sense that node
xis in the communication range of node y if and only if
node y is in the communication range of node x. Each node
is identified by a MAC address as well as a short identifier
(ID). The ID is chosen by each node at random, included in
the header of each packet transmitted on channel c0, and
changed if the node detects that its ID is already in use by
another node [4].
Time is partitioned to frames consisting of a
constant number of fixed duration time slots. The number
of time slots per frame on channel cm is denoted by sm,m =
0, . . .,M, and a time slot on channel cm is identifiedby the
index of this time slot within a frame on channel cm.On
channel c0, each frame is partitioned into three sets oftime
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slots: L, R, and F. The F set isassociated with RSUs, while
the L and R sets are associated with vehicles moving in left
and right directions, respectively.Every node (i.e., vehicle
or RSU) is equipped with a global positioning system
(GPS) receiver and can accurately determine its position
and moving direction using GPS. The current position of
each node is included in the header of each packet
transmitted on channel c0, and synchronization among
nodes is performed using the 1PPS signal provided by any
GPS receiver [10]. The rising edge of this 1PPS is aligned
with the start of every GPS second with accuracy
within100 ns even for inexpensive GPS receivers.
Consequently, this accurate 1PPS signal can be used as a
common time reference among all the nodes. All the
channels are slot synchronized and, on each channel, each
second containsan integer number of frames as shown in
Fig. 2 for channelc0. Hence, at any instant, each node can
determine the index of the current slot within a frame on
any channel cm, m =0, . . .,M, and whether it belongs to the
L, R, or F set on channel c0. In case of a temporary loss of
GPS signal, the synchronization among different nodes can
still be maintained within a certain accuracy for a time
duration, which depends on the stability of the GPS
receiver’s local oscillator at each node If the GPS signal is
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International Journal of Engineering Trends and Technology (IJETT) – Volume 15 Number 6 – Sep 2014
lost in a certain area for a long duration (longer than a
specified threshold), a distributed synchronization scheme,
such as the one presented in ,should be employed until the
GPS signal is recovered[11][12].
II. PROPOSED WORK
In this paper we are proposing an efficient collision free
broadcasting approach with dynamic slot allocation table
and geo codings based mechanism for computing the
OBU
distance between the on board units and if distance exceeds
the minimum distance, here every onboard unit can be
identified by geo parameters (latitude and longitude),
messages can be broadcasted to other On board units and
road side unit broadcasts the packets whenever a new data
packets available at its end.When any OBU receives data
packet request initially it checks slot allocation table, if
allocation table is free ,it updates allocation table with
onboard unit id and data packets else it increases the
allocation table size dynamically whenever required
RSU
Broadcast
Position by latitude
and longitude
Fig 2 : Architecture
Every On Board Unit in the vehicle can be
identified by the geo-codings (Latitude and longitudes) of
the vehicle positions and it measures the distance between
the OBU to OBU and OBU of the Vehicle receives the data
packets which are broadcasted by the Road side unit. On
Board Unit is the communication device in the vehicle,
communicates with other on board units and Road side
units. Receives and send data packets from the OBU and it
receive data packets from RSU.
Our protocol supports OBU data packet
transmission, based on transmission range to everyone on
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board unit communicates efficiently without any collision
with their channels. When a node or vehicle x tries to
communicate with other node y with in transmission range,
Node x allocate the free slot for node y to make it collision
free and communicate based on the channel allocation table
maintained at the node. For allocation of nodes computes
the distance between the nodes with their geo-codings,
based on the distance allocate the slot for the node. In the
above algorithm Set N represents set of nodes or vehicles
which has on-board units; OBUs can transmit and the
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International Journal of Engineering Trends and Technology (IJETT) – Volume 15 Number 6 – Sep 2014
following algorithm shows efficient broadcasting and
dynamic slot allocation as follows.
Geo Based Broadcasting and Collision Handling
Step3: prioritize the nodes based on single hop &multi-hop
Input: N(N1,N2,…..Nn)
Step4: transmit msg to OBU and update allocation table
G(g1(x1,y1),g2(x2,y2)……gn(xn,yn))
OBU(OBU1,OBU2,…….OBUn)
RSU(RSU1,RSU2………..,RSUn)
Output: Collision free & optimal communication between
OBUs & RSUs
Step1: initiate nodes N, on board unit(OBU) and road side
unit(RSU)
Update slot table
receives the data packets from other on board units and
road side units. G indicates set of geo parameters or
location parameters of the vehicles, RSUs are the road side
Every OBU always be in listening mode whenever a
message received at allocation table, updates slot allocation
table dynamically and computes Euclidean distance if
exceeds minimum threshold broadcast message to
respective OBUs , whenever message received by receiver
OBU, it can be removed instantly from allocation table.
EXPERIMENTAL ANALYSIS
Step2: while(free)
Receive msg:=msg(OBUi)
Step3: get geocode(g1,g2,g3…..gn) from active nodes
Step4: Compute Euclidian distance between two nodes
For experimental implementation we had used Network
or socket programming in C#.net .Consider an example of
five on board units OBUs {OBU1, OBU2, OBU3 ,OBU4,
OBU5} and two Road side units RSUs {RSU1,RSU2}.
Send msg to OBU
Individual on board units consists of allocation table
which contains Source node, message and time stamp.
Allocation table is dynamic and it can increase allocation
table size automatically whenever it reaches its maximum
size to make collision free communication and
continuously forwards messages to view panel with time
stamp and releases from allocation table immediately.
Allocation tables shows as follows
Else
Priority Node
Message
Time Stamp
Ignore msg
3
OBU2
Min Dist Reached 09 :
09:14 6:50 pm
1
OBU3
Min Dist Reached
09 : 09:14 7:00
2
OBU4
Min Dist Reached
09 : 09:14 7:00
E= (x2-x1)2+(y2-y1)2
Step5: get Min distance
Step6: if(mindis< threshold value)
Collision Handling
Step1: Initiate the allocation of nodes
Step2: Check slot availability of input node
If(slot available)
units to broadcast data packets to nearest OBUs whenever
update available.
Message can be received by any node whenever
Euclidean distance between two nodes is minimum or other
on board unit meets minimum threshold value set in on
board unit which is calculated with geo-codings of OBU1
and OBU2 like (0.325623, 0.435453) and (325621,
0.435450).
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E.D=Math.Sqrt((x2-x1)2+(y2-y1)2) If Euclidean distance
not satisfies with minimum distance message can be fired
to respective nodes and checks allocation table, if it reaches
maximum size increases allocation table size dynamically
and updates message and then transmits to view panel to
the end user.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 15 Number 6 – Sep 2014
Our experimental results shows efficient results than the
traditional approach as follows
Throughput (packet/Slot)
12
10
8
6
Traditional
4
Proposed
2
0
Low Med High Very
high
The above graph shows traffic level in x axis
with different density levels like low, medium, high and
very high and in y axis percentage of traffic collision, the
following status or report of graph generated when a node
or on board unit transmits messages to allocation table for
its slot, if it is busy expand the allocation table
dynamically, so at any level it maintains consistency.
The
experimental
results
shows
more
performance over traditional approaches when the density
of the land is either low, medium or high because our
approach work towards collision free with dynamic
allocation and increases the performance by forwarding
the data packets to on board unit which has minimum
Euclidean distance.
[3] Performance Analysis of the IEEE 802.11 MAC Protocol for DSRC
with and without Retransmissions Md. Imrul Hassan∗, Hai L. Vu∗and
Taka Sakurai†.
[4] VeMAC: A TDMA-Based MAC Protocol for Reliable Broadcast in
VANETs Hassan Aboubakr Omar, WeihuaZhuang and Li Li.
[5] R. Mangharam, R. Rajkumar, M. Hamilton, P. Mudalige, and F. Bai,
“Bounded-Latency Alerts in Vehicular Networks,” Proc. Mobile
Networking for Vehicular Environments, pp. 55-60, May 2007.
[6] F. Watanabe, M. Fujii, M. Itami, and K. Itoh, “An Analysis of Incident
Information Transmission Performance Using MCS/ CDMA Scheme,”
Proc. IEEE Intelligent Vehicles Symp. (IV ’05), pp. 249-254, June 2005.
[7] H. Nakata, T. Inoue, M. Itami, and K. Itoh, “A Study of Inter Vehicle
Communication Scheme Allocating PN Codes to the Location on the
Road,” Proc. IEEE Intelligent Transportation Systems Conf. (ITSC ’03),
vol. 2, pp. 1527-1532, Oct. 2003.
[8] IEEE Std 802.11p-2010, Standard for Information TechnologyTelecommunications and Information Exchange between Systems-Local
and Metropolitan Area Networks-Specific Requirements Part 11: Wireless
LAN Medium Access Control (MAC) and Physical Layer (PHY)
Specifications Amendment 6: Wireless Access in Vehicular
Environments, IEEE, pp. 1-51, July 2010.
[9] IEEE Std 802.11-2007 (Revision of IEEE Std. 802.11-1999), Standard
for Information Technology Telecommunications and Information
Exchange between Systems-Local and Metropolitan Area NetworksSpecific Requirements - Part 11: Wireless LAN Medium Access Control
(MAC) and Physical Layer (PHY) Specifications, IEEE, pp. 1-1184, June
2007.
[10] M. Hassan, H. Vu, and T. Sakurai, “Performance Analysis of the
IEEE 802.11 MAC Protocol for DSRC Safety Applications,” IEEE Trans.
Vehicular Technology, vol. 60, no. 8, pp. 3882-3896, Oct. 2011.
[11] S. Eichler, “Performance Evaluation of the IEEE 802.11p WAVE
Communication Standard,” Proc. IEEE 66th Vehicular Technology Conf.
(VTC ’07-Fall), pp. 2199-2203, Oct. 2007.
[12] F. Borgonovo, A. Capone, M. Cesana, and L. Fratta, “ADHOC
MAC: New MAC Architecture for Ad Hoc Networks Providing Efficient
and Reliable Point-to-Point and Broadcast Services,” Wireless Networks,
vol. 10, pp.
BIOGRAPHIES
Sekhar Dunna completed M.Sc.,
degree in Computer Science from
Annamalai University and He is
pursuing M.Tech degree in the
Department of Computer Science and
Engineering, from Aditya Institute of
Technology And Management.
IV. CONCLUSION AND FUTURE WORK
We are concluding our research work with efficient
broadcasting protocol and dynamic allocation table
updating whenever allocation table exceeds its maximum
size and dynamically computes distance between on board
units and forwards data packets to Other OBUs but priority
based on Euclidean distance.
We can enhance our concluded work by enhancing or
identifying packet error rate and acknowledgement from
the receiver node whenever a successful transmission or
failure happened while transmission of data packet.
REFERENCES
Tatapudi Prabhakhara Rao completed
his B.Tech Computer Science &
Engineering from jntu Hyderabad. He
completed M.Tech Computer Science
& Engineering from Jntu Kakinada.
Area Of Interstest: Image Processing,
Wireless Sensor Networks, Mobile
Computing, Network Security. He Is member Of CSI,
ISTE & IE.
[1] Current Trends in Vehicular Ad Hoc Networks Ghassan M. T.
Abdalla*, Mosa Ali Abu Rgheff*and Sidi Mohammed Senouci**
[2] Vehicular Ad Hoc Networks: A New Challenge for LocalizationBased Systems q Azzedine Boukerche a,*, Horacio A.B.F. Oliveira a,b,c,
Eduardo F. Nakamura b,d, Antonio A.F. Loureiro.
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