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Mainly two types of communication modes are
used in VANETs, Vehicle-to-Vehicle (V2V) and
Veh i c l e - t o - I n f r a s t r u c t u r e (V2I), both h a v i n g
connectivity issues as their prime problem. In V2V,
variation in speed and high densities of traffic often
results in low data transfer rates and limits the
communication. In V2I mode, data communication rate
is slower on highways due to the limited availability of
Roa d Si d e Un i t s ( R S U s ) [i i i , i v ] . T h e ma i n
considerations in design of VANETs solutions are to
minimize delay and packet loss during communication.
Delay sensitive Intelligent Transportation System
(ITS) applications (e.g., safety-related solutions) and
value-added applications (such as entertainment and
mobi le commer ce) req uire conti nuous I nternet
connectivity with minimum delay and packet loss [v].
Most of the VANETs applications require seamless
mobility, with accessibility and service continuity,
regardless of location and technology used. Many
delay sensitive applications require fast handover. Fast
handover is a crucial requirement to fulfil specially in
small coverage networks like Wi-Fi etc. because
vehicles spend only a short period of time at each
access point due to their high speeds.
In this paper, we propose a novel approach that not
only considers RSS parameters but also considers GPS
location information along with maps for handoff
decision. RSS alone, in fact is not considered much
reliable for handoff decision as its accuracy may
fluctuate significantly, especially in VANETs scenarios
which can cause unnecessary handovers leading to
delay and packet loss [vi].
We propose that every vehicle has a GPS enabled
scanning module which scan and query the nearby
vehicles to get their directions and speeds through on-
board GPS enabled scanning module. The scanning
module in each vehicle makes a queue of all available
vehicles for connection. The vehicles with maximum
availability (connectivity duration) are put on top of the
queue and given priority. This will minimize the time to
find the next best available vehicles for connectivity.
When the connection from the previously connected
105
Abstract-Vehi cular ad-hoc n etwork faces many
challenges, in particular frequent handoffs due to high
mobility of vehicles is a serious performance limitation
factor and is probably the most critical process in terms
of packet loss and delay. In this paper an efficient
mechanism of Vehicular Ad-hoc Networks (VANETs)
is proposed for making handoff decision that considers
both Received Signal Strength (RSS) and Global
Positioning System (GPS) information along with
maps. Furthermore; the proposed mechanism focuses
on nodes moving at high speeds while receiving and
saving the relevant information in buffers. This
particular approach not only minimizes delay and
packet loss but is also used to retransmit the lost packets
locally. The addition of this capability in the proposed
mechanism contributes in improving the packet loss in
les s cr o w d e d ar e a s ha v i n g l i m i t e d av a i l a b l e
connectivity.
Ke y w ords- A d -Hoc Ne t works, M obile Ad- H oc
networks, Vehicular Ad-Hoc Networks, Intelligent
Transport System, Short Range Communication
I. INTRODUCTION
Over the past few years, a lot of research has been
done in the area of mobile ad-hoc networks (MANETs).
In M A N E Ts m o b ile n o d es c a n conne c t an d
communicate with each other via one-hop or multi-hop
commu nicatio n links wit hout t he need for an
infrastructure [i].
A VANETs is a special type of MANET having
fewer limitations as compared to MANETs. In
VANETs the movement of vehicles is predictable as
they always move on predefined roads and the
infrastructure only caters for movements along the
road. Secondly, VANETs face no limitations of
resources such as power or processing capabilities as
almost all the devices have adequate power provided by
their host vehicles. Thirdly, in VANETs all the
messages are delivered by using broadcast instead of
unicast [ii].
A Location Based Delay and Packet Loss
Optimized Communication Mechanism
involving Handoffs in Vehicular Ad Hoc
Network
1 2 3
M. N. Majeed , M. Zafrullah , M. A. Azam
1,2,3University of Engineering and Technology Taxila, Pakistan
1nadeem.majeed@uettaxila.edu.pk
Technical Journal, University of Engineering and Technology (UET) Taxila, Pakistan Vol. 22 No. II-2017
106
architecture of VANETs can be executed on top of any
of the available routing protocols. The basic gateway
selection have provided the finest performance with Ad
hoc On-Demand Distance Vector (AODV) on top as
compared to Destination-Sequenced Distance-Vector
(DSDV).
Ankita and others [x] have introduced a cluster
based method in their paper for implementation of
VANETs. As VANET is an enhanced version of
MANET, therefore several handoffs related problems
that could not be removed earlier in MANETS have
easily been removed using this proposed cluster based
ap p roach in VAN ETs. For imp l e mentin g t h is
infrastructure in VANETs, cluster oriented routing has
been employed, by using AODV and AODV+ as the
two routing protocols.
In VANETs, the fast moving vehicles and the
limited coverage areas of 802.11 devices have made the
Mobility Management as one of the challenging tasks
to accomplish. This fast movement of vehicles leads to
frequent occurrence of handoffs. The handover results
in reducing the throughput of the network and causes
sudden interruptions in previously build connections.
The movement of vehicles in VANETs is assisted by the
Mobile IPv6. Some of the most apparent issues of
MIPv6 are the enhanced latency, packet loss and
triangular routing. Therefore, a handoff structure based
on FMIPv6 and HMIPv6 has been proposed [xi] that
will eventually results in the lessening 802.11 based
handoff latency by eradicating the DAD procedure and
also by addressing other associated issues that rises
when the structure is applied to the vehicular network.
Many wireless communication mechanisms have
been anticipated for VANETs, such as IEEE802.11p is
recommended for supporting the small to medium
range transmissions in order to cope with the features of
vehicular network environments [xii]. The vehicles in
these environments are characterized by higher range
of mobility which results in frequent disruption of
already existing connections. Still, the task of mobility
management is quite an attractive and challenging task
particularly for VANETs and IEEE802.11p. Zagrouba
and others [xiii] have proposed a new method of the
handoff for the standard IEEE802.11p in perspective of
the vehicular transmissions. The proposed handoff
algorithm has been based on vehicle to infrastructure
communications and helps in tackling the issues that
have been caused either by listening the announcement
of the frame service by the vehicle residing on the CCH
based channel or by anticipating the full handover
period before it begins. The results of simulation and
evaluation of performance have shown that the
proposed arrangement can reduce the handoff delay
and the packet loss quite efficiently.
Hybrid Wireless Vehicular Network originates by
integrating several types of networks to exploit their
payba c k s and o p t i mize t h e o v e r a ll n e t work
performance. The task of achieving ubiquity is quite
vehicle is about to end then the next best available
vehicle will be maintained on top of the queue by the
scanner module. This will minimize the delay time in
transmission during routing and switching between
vehicles.
The proposed system focuses on nodes moving
and receiving information as well as saving the relevant
information in buffer. This particular approach not only
minimizes the packet loss but also helps to retransmit
the lost packets later on. The addition of this capability
in the proposed system contributes in improving the
packet loss in less crowded areas having limited
available connectivity. Packets are stored in the buffer
before handoff takes place and the RSS level is about to
reach it s thres hold le vel, the data packets for
transmission are buffered and during handoff process
the dropped packets are retransferred.
Rest of the paper is as follows: section II discusses
the literature review, section III contains system
mechanism, results and discussion is in section IV and
conclusion is in section V.
II. LITERATURE REVIEW
As in today's world VANETs seems to be among
one of the most emerging techniques, therefore one of
the challenging research questions relating to VANETs
is the Mobility management that helps in supporting a
wide range of intelligent communication system based
applications. The importance of VANETs for executing
seam les s inter-vehicle communica tio n is quite
appreciable because they offers infrastructure-less,
economic and easily configurable communications.
However, the integ ration of Interne requires a
corresponding mobility assistance of the underlying
vehicular ad-hoc network. Ravi and Neeraj [vii] have
studied the network mobility method in detail in the
context of vehicular ad-hoc network and proposed the
model that has described the shifting of vehicles within
several networks while they are moving. Their
proposed handoff method was efficient at reducing the
handoff latency and the overhead occurring due to
packet loss.
The problem of finding the dead and blind spots
and identifying out of coverage areas are severe
problems occurring in the rural and some parts of the
urban areas as the network infrastructure has not been
deployed in those areas [viii]. For handling these issues
a novel approach i.e. the hop to hop relay approach for
vehicular transmissions has been proposed in order to
extend the range of coverage and reducing the
frequently generating handoffs. The proposed scheme
[ix] allows for continuous connection of vehicles to the
roadside infrastructure network which is the Universal
Mobile Telecommunication Service (UMTS) for this
particular research based project. The discovery of
Relay vehicles and selection of the gateways have been
discussed and investigated in detail. The proposed
Technical Journal, University of Engineering and Technology (UET) Taxila, Pakistan Vol. 22 No. II-2017
107
strength greater than the current one. The source
vehicle sets the minimum value of its RSS in the current
connectivity as a threshold value 'Y'. In case of reduced
signal strength from the current cell boundary, the
source vehicle firstly checks the RSS for the base
station it is currently connected to, if the RSS still
exceeds the threshold value than there is no need of
handoff and the vehicle remains attached to the current
base station.
The second case arises when the RSS from the
currently connected base station lags behind the fixed
threshold value. In such scenario, the source vehicle
then searches for neighbouring cells except the current
one having signal strength greater than the threshold
value 'Y'.
A. Checking the Desired Signal Strength
The algorithm works in a flow where a source
vehicle originates the communication process with one
of the neighbouring vehicles as shown in algorithm 1.
To achieve the desired connectivity, the source vehicle
checks the RSS of the neighbouring vehicles. When the
source vehicle finds a neighbouring vehicle with signal
strength greater than the currently connected vehicle,
the source vehicle tries to connect with the new vehicle.
Each vehicle sets a threshold value 'Y' of received
signal strength; which is the lower bound of threshold
value.
For the purpose of initiating the handoff process
the vehicle starts adjusting its packet's window size.
When the vehicle sense lower RSS, it immediately
starts increasing the packets window size. This will
eventually lower the rate of sending and receiving
packets, which ultimately results in low packet loss and
reduced delay that mostly occurs due to handoff
initiation process.
difficult in the presence of several different network
types. The aim of the proposed architecture [xiv] is to
achieve pervasiveness in Hybrid Wireless Ad-Hoc
Networks, which is done by decreasing the handoff
delays originating during the handoff mechanism and
the existence of moving vehicular network nodes helps
in removing the power constraint imposed on the
moving nodes. The idea of choosing Ideal Access
terminal has been presented in order to attain fast and
quick han doff by means of the Early Han doff
procedure.
In most of the previous work no one has used the
pre scanner to make the queue to make the handoff fast.
Our proactive technique find the next node for handoff
well before the handoff process. This leads to minimize
the time required for handoff.
III. SYSTEM MECHANISM
The pr o p o s e d me c h a nism o f VANETs i s
implemented in a highway scenario where vehicles on
the road are moving in two directions. The two way
roads are further divided into four lanes. The base
stations are deployed at both sides of the roads but at
alternate positions. There is only one road side unit
(RSU) providing transmission facilities to both sides of
the roads up to 500 meter. This range depicts the region
of connectivity for the current base station. A network
may be comprised of several base stations. The vehicles
moving in connectivity zone of a base station can
smoothly switch between various base stations by
initiating the handoff process. The devised algorithm
works for handover optimization on the basis of RSS.
The idea is to implement handoff before the link failure
occurs. This complete scenario is shown in Fig. 1
Fig. 1. System Structure
Vehicles communicate directly with the base
stations or through other vehicles directly in range of
base station. Whenever a moving vehicle i.e. a source
vehicle senses the low received signal strength in its
current connectivity range, it goes for a handoff process
by checking the neighbouring cells having signal
Technical Journal, University of Engineering and Technology (UET) Taxila, Pakistan Vol. 22 No. II-2017
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108
D. Scenario of Handoff Generation with Multiple
Intermediate Nodes Involved
While scanning process is in progress, it may be
possible that the source vehicle does not find any base
station in its direct range of communication. The
vehicle must have been moving on the other side of the
road where base station is not deployed for that specific
communication zone. The source vehicle then sends
the message for gathering RSS of the base station by
involving the intermediate vehicle which is moving in
direct communication range of the base station. The
intermediate vehicles further deliver the message to its
neighbouring vehicles. The process continues until the
message is reached to the base station. The base station
upon receiving the request message, prepares the reply
message and sends it back to the intermediate vehicle
which further transmits back the message parcel to the
source vehicle.
The source vehicle checks the RSS of the base
station with respect to the current threshold value Y. If
the result is greater than Y, the source vehicle finally
goes for the handoff process and shifts its connectivity
to the new base station.
E. Scenario of Handoff Generation with Single
Intermediate Node Involved
The alternative scenario for this handoff occurs
when only a single intermediate vehicle is involved in
th e scan n ing proce s s. For s u ch sit uatio n, the
intermediate vehicle on receiving the message,
computes its own RSS against the threshold value Y of
the source vehicle. For exceeded value of signal
strength, the intermediate vehicle directly forwards the
request to its base station and the source vehicle is
successfully connected to the new base station sharing
the connectivity to the intermediate vehicle. The
intermediate vehicle can also search for the new
roadside unit if it is receiving the less signal strength
than the threshold value Y. The intermediate vehicle
then becomes the source vehicle and the whole
searching process is repeated for the intermediate
B. Scanning Of Neighbouring Vehicles for Handoff
Generation
The handoff occurrence process requires scanning
of the neighbouring vehicles moving in the same
direction as the source vehicle. The scanning module
has been introduced in the proposed algorithm for the
purpose of implementing the handoff process and
finding the vehicle with best possible RSS. The
scanning of vehicles is accomplished through GPS
coordinates. The scanner then filter out the vehicles
with best RSS and checks the selected vehicles for their
speed, direction and velocities. If the scanner failed in
searching any desired vehicle then the handoff process
will be delayed till the presence of some nearby vehicle
is suspected. The searched vehicle with almost similar
speed and direction is selected for initiation of handoff
process and the scanned results of the remaining
vehicles with same direction and approximately same
speed are shifted to the queue for later usage. The
oppositely moving vehicles among the scanned
vehicles are discarded as communication to these
vehicles can no longer survive and therefore are not
required in the process of handoff implementation.
C. Introducing Queues for Handoff Generation
As shown in algorithm 2, the vehicles added to the
queue are arranged in the FIFO order. The vehicles with
best matching speed and direction are added from the
front of the queue. On de-queuing the vehicle entered
first will be given precedence and it will be de-queued
from the rear end of the queue. When the vehicle
connected to the new RSU with greater RSS again
receives less signal strength from the currently
connected vehicle or RSU, and then instead of
re-applying the whole scanning process, the source
vehicle first checks the vehicles through the queue. The
vehicles in the queue are computed for their RSS value.
Upon acquiring the best RSS the corresponding
vehicle/RSU is selected from the queue for the purpose
of handoff initiation process. Ultimately the handoff
process with the resultant vehicle is carried out and the
process of communication is again resumed. The
window size of buffer which has been increased before
the handoff process is again narrowed down to its
normal value and the process of packets transmission is
restarted.
Technical Journal, University of Engineering and Technology (UET) Taxila, Pakistan Vol. 22 No. II-2017
109
Technical Journal, University of Engineering and Technology (UET) Taxila, Pakistan Vol. 22 No. II-2017
the neighbouring cells. The information is stored in the
map for once and then it is utilized for estimation
purpose.
The information from the moving vehicles is
submitted to the maps in the base stations by using GPS
coordinates. All the vehicles on the road are equipped
with the GPS devices that provide vehicles with the
capability of predicting their accurate positions on the
road. The position of the vehicles is then transmitted to
the base station which is ultimately stored in the
database at the base station. The base station has a back
end database for the vehicles in the coverage area of the
base station. The database is aimed at storing the
trans mitt ed veh icl e's infor mat ion requi red for
probabilistic handoff conductance. Base station uses
this information sent via GPS coordinates to perform
calculations for all of the active vehicles in its coverage
zone.
The above described scheme has been utilized in
current research project of handoff optimization. The
distinguishing feature of the scheme is that it makes use
of the road information and limits the bandwidth usage
to achieve efficiency in utilization of the shared
resources.
H. Advantage of Using Maps
The vehicles are attached to the Base Stations
through the back end network consuming the limited
reserved bandwidth assigned to each base station. In
mobile ad-hoc networks, vehicles can specifically be
designated as the mobile stations. As discussed earlier,
each mobile station is equipped with a GPS system for
sending GPS coordinates to the Base Station. On the
basis of transmitted coordinates, the Base station
calculates the location of the vehicle and can further
predict its path based on probabilistic approach [xv].
The base stations uses a map service for receiving
GPS coordinates as reference points and defining the
structure of roads hierarchy and traffic conditions in an
efficient manner. Therefore, the utilization of maps can
be proved as an effective approach in predicting either
the current scenario of handoff or the probability of
taking handoff. The overall bandwidth reserved for the
network is attuned dynamically whenever there is a
possibility of handoff to occur [xvi].
I. Reasons for Generation of Handoff
The need for initiating the handoff process is a
result of the less amount of received signal strength in
functional channel of the cell. The issue of reduced
signal strength may arise due to various possible
reasons including the maximum operating capacity of
the channel, the amount of bandwidth reserved for the
channel and the extreme signalling range of the
channel. The operating capability of the channel
depends on the number of requests arriving at the
channel due to handoffs occurring in the network [xvii].
Depending on the arrived requests, the received signal
strength of the channel can therefore be measured.
vehicle.
F. Setting Threshold 'Z'for New Connection
As shown in last step of the algorithm 1, the source
vehicle sets the new threshold value i.e. 'Z' which is the
minimum amount of signal strength it can receive from
th e n e w R S U . The source ve h icle can enjo y
communications in the networking zone of the new
base station. Although, handoff has been conducted for
once, yet the source vehicle keeps on checking the
amount of RSS at every point against the new threshold
value 'Z'. As long as the value is exceeding 'Z', the
source vehicle can conduct communications. The
moment it senses the value going below 'Z', the source
vehicle starts searching process and the whole process
of examining the signal strengths of other base stations
continues. The searching process is a kind of an
umbrella activity that is applied throughout the life span
of vehicle on the road. The need for handoff has no end
point except that the vehicle eventually reaches its
destination.
The handoff process is initiated by sending the
request message to the new base station for checking
the signal strength of the new base station. The request
message can be transmitted by forwarding through
intermediate nodes or scanning the whole network. On
availability of the new base station with required signal
strength the handoff request is entertained.
G. Util i z a t i o n of Ma p s in Ha n d o f f fo r GP S
Coordinates
Handoff request can be implemented on the basis
of information gathered through maps and GPS
coordinates. The base stations are further connected to
the mobile switching centres at the back end. The
network servers are located at the back end mobile
switching centres. All the required communications are
conducted through the back end network server via
base station at front end. The maps are added in the base
station which provides services to the source vehicle in
depict ing the rig ht pat h for its journey to th e
destination. The layout of the roads in the scenario of
VANETs is organized in such a manner that it can place
co nstr aint s on the m ovem ent of t he veh icle s.
Furthermore, the movement of vehicles on the roads is
strictly restricted by some traffic conditions that keep
on changing at different intervals of time. The burst
conditions of traffic can limit the comfortable and
smooth initiation of handoff process.
The scheme of adding maps to the base stations is
based on the utilization of vehicle's information for
predicting the possibilities of handoff process to the
neighbouring cells. The information of the vehicle
includes uniform speed of the vehicle with which it is
moving and the direction of moving vehicle. Along
with that the base station uses information stored in the
base station regarding road condition for prediction of
the probability of handoff occurrence especially with
110
Fig. 2. Packet Loss for five moving vehicles
Fig. 3. Packet Loss for ten moving vehicles
B. Average Packet Delay
The simulation results show that as the velocity of
vehicle increases, it affects the handoff delay in every
handoff algorithm. When the vehicle velocity increases
then there is a little time for transmission and scanning
at the same time which increased the delay, but, in
DePOVHH, as the velocity of vehicle increases it has
no reasonable effect on handoff delay. Because before
handoff performing active scanning is performed. In
the Fig. 4 and Fig. 5 indicates that the packet delay
comparison for of different number of vehicles, 5and
10 respectively. The result shown that the at the
velocity of 25m/s, the DePOVHH's average packet
delay in 5 moving vehicles is 138.69ms, 154.73ms in
10 moving vehicles. It shows that as with the increase in
number of vehicles, the packet delay also increases.
The reason for that is since there are so many vehicles to
establish the next connection before the signal became
weak.
IV. EXPERIMENTAL SETUP AND
EVALUATION RESULTS
Th e expe rime nts have been condu cted o n
ESTINET [xviii] for different scenarios. Vehicles are
equipped with devices capable of having network
connections. Transmissions among the vehicles are
carried out for varying parameters including frame rate,
bit rate and bandwidths. Each experiment has been
conducted twice, once for the 802.11p where handoff
optimizations are carried out without any available
sc anni ng opt i on. T he sec ond ex peri ment s are
conducted for our proposed work which is named as
Delay and Packet loss based Optimized Vertical and
Horizontal Handoff algorithms (DePOVHH), where
scanners are involved for pre-scanning of nearby
ve h i c l es. The experi m e n t a l s e tup chosen for
transmitting video data among vehicles is shown in
Table I. The encoding scheme chosen for this specific
media type is MPEG-4and maximum of 30 frames are
transferred per second.
TABLE I
VIDEO TRANSMISSION PARAMETERS DURING V2V
HANDOFF SIMULATION
As MPEG-4 f o r m a t u s e s le s s bandwidth
[xix, xx], therefore this encoding scheme is used with
150kbps bit rate. Simulation has been run and
pe r f ormanc e of t h e s c a nner and non- s c a nner
algorithms is evaluated. The evaluation results are
shown for delay, packet loss and throughput.
A. Average Packet Loss
The simulation results in Fig. 2 and Fig. 3 shows
that as the vehicle's velocity increases, the packet loss
also increases. The performance of vehicle increases as
co mpar ed to the exist i ng han d off v eloci ty in
DePOVHH. The e ffect o f DeP OVHH is more
prominent when the velocity of vehicle is less than
25m/s which is the optimize speed on highway, where
the packet loss is less than 1000. The number of packet
loss is 1297 for ten number of vehicles, where
DePOVHH value is 726. This shows that DePOVHH
algorithm enhanced the network performance.
Technical Journal, University of Engineering and Technology (UET) Taxila, Pakistan Vol. 22 No. II-2017
Media Type
Encoding Scheme
Frame Rate
Payload Type
Bit Rate
Sampling Rate
Bits/Sample
Session Bandwidth
Road Topology
Video
MPEG-4
30 frames/Second
26
150 kbps
90kHz
3 Bit
1600kbps
A four lane road
1100
1000
900
800
700
600
500
400
300
200
100
0
Number of Packet Loss
5m/s 10m/s 15m/s 20m/s 25m/s
Speed (m/s)
0m/s 30m/s
1400
1200
1000
800
600
400
200
0
Number of Packet Loss
5m/s 10m/s 15m/s 20m/s 25m/s
Speed (m/s)
0m/s 30m/s
DePOVHH
DePOVHH
111
Fig. 7.Average Throughput for ten moving vehicle
V. CONCLUSION
This research based project was aimed at providing
delay tolerant optimization techniques for horizontal
and vertical handoff occurrences particularly for
Vehicular Ad-hoc Networks. An improved technique
for handoff has been proposed that caters for delayed
packet losses and frequent link failures. The underlying
mechanism has been organized to provide maximum
throughput while handoff process is in progress. The
parameter selected for proposed algorithm to work
upon is the Received Signal Strength and the desired
information for smooth processing of algorithm is
provided through GPS. For experimental purposes, the
vehicles on the road are allowed to move randomly
with varying speeds and velocities, creating a road map
scenario of a two-way traffic. The optimization is
achieved by introducing a scanner module through
which vehicles pre -scanne d th eir neighbouring
vehicles and creates a priority queue for buffering the
location of nearby vehicles. On link failure, vehicle
selects the top queued item with maximum priority for
immediate connectivity. This particular pre-scanning
ap p r o a ch s a ves time in s e arching fo r a ne w
connectivity and hence, proved to be the best approach
in reducing amount of packet loss due to link failures.
Moreover, th e propo sed sys tem also offers an
opportunity for buffering the relevant information of
vehicles during on-going communications, which in
turn can be suff icient in achi evin g max imum
throughput even on link failure. The packets stored in
the buffer are later on retransmitted on finding the new
connectivity in range.
The results of simulations for the proposed
algorithm clearly depicts the efficiency measure of the
algorithm achieved in terms of the reduced packet loss,
delay and increased throughput compared to previous
approaches adopted for handoff implementation.
The algorithm can be further improved in terms of
efficiency by implementing it for infrastructure
optimization, where vehicles can also communicate
with infrastructure.
Fig. 4. Packet Delay for five moving vehicle
Fig 5. Packet Delay for ten moving vehicle
C. Average Throughput
The simulation results of Fig. 6 and Fig. 7 shows
the average throughput for different vehicle velocities.
From the simulation result it is clear that increase in
vehicle velocity greatly affect the average throughput.
Packet loss and delay results in scanning phase which
also affects the average throughput. As the vehicle's
velocity increases, the packet lost increases and
throughput decreases. From Fig. 7 it is clear that as the
velocity of vehicle increases, throughput decreases for
five moving vehicles. From all of these simulation
results it is clear that the association and authentication
process between the base station and vehicle is not
much affected as the velocity of vehicle is increase.
Fig. 6. Average Throughput for five moving vehicle
Technical Journal, University of Engineering and Technology (UET) Taxila, Pakistan Vol. 22 No. II-2017
1000
800
600
700
600
500
400
300
200
100
0
Average Throughput (kbps)
5m/s 10m/s 15m/s 20m/s 25m/s
Speed (m/s)
1000
800
600
700
600
500
400
300
200
100
0
Average Throughput (kbps)
5m/s 10m/s 15m/s 20m/s 25m/s
Speed (m/s)
200
180
160
140
120
100
80
60
40
20
Delay (ms)
5m/s 10m/s 15m/s 20m/s 25m/s
Speed (m/s)
0m/s 30m/s
180
140
120
100
80
60
40
20
Delay (ms)
5m/s 10m/s 15m/s 20m/s 25m/s
Speed (m/s)
0m/s 30m/s
DePOVHH
DePOVHH
DePOVHH
DePOVHH
112
2012.
[xii] R. Zagrouba, H. Hayouni, and F. Kamoun,
"Handover optimization wi thin vehicular
networks," in Computer Applications and
Information Systems (WCCAIS), 2014 World
Congress on, 2014, pp. 1-5
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Technical Journal, University of Engineering and Technology (UET) Taxila, Pakistan Vol. 22 No. II-2017
