A Novel Intelligent Cluster-Head (ICH) to Mitigate the Handover Problem of Clustering in VANETs

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A Novel Intelligent Cluster-Head (ICH) to Mitigate
the Handover Problem of Clustering in VANETs
A.H. Abbas*1, Mohammed I. Habelalmateen2, L. Audah3, N.A.M. Alduais4
Wireless and Radio Science Centre (WARAS) Faculty of Electrical and Electronic Engineering
Universiti Tun Hussein Onn Malaysia 86400 Parit Raja, Batu Pahat, Johor, Malaysia1, 2, 3, 4
Department of Computer Technical Engineering, College of Technical Engineering
The Islamic University, 54001 Najaf, Iraq2
Abstract—The huge development in the number of Vehicle
factories have resulted in many people having lost their life due
to accident, which has made vehicular Ad-hoc networks
(VANETs) hot topic to enable improved communication between
vehicles aimed at reducing the loss of life. The main challenge in
this area is vehicle mobility, which has direct effect on network
stability. Thus, most previous studies that discussed clustering
focused on cluster formation, cluster-head selection and the
stability of cluster to reduce the impact of mobility in the
network, with little attention given to the clusters when passing
from base-station to neighbor base-station. Therefore, this study
focused on handover problem that occurs after cluster formation
and cluster-head election during cluster passing from base
station to base station, known as overlapping area. As the cluster
in an overlapping area receives two signals from different base
stations, the signal arriving at the cluster becomes weak due to
interference between two frequencies resulting in loss of cluster
information in the overlapping area. In this study, proposed a
novel method named Intelligent Cluster-Head (ICH), which is a
controller on two clusters that are used to change uplink between
clusters to solve the handover problem in the overlapping area.
The proposed method was evaluated with VMaSC-1hop method.
The proposed method achieved percentage of packet loss up to
0.8%, percentage of packet delivery ratio (PDR) 99%, percentage
of number of disconnected links 0.12% and percentage of
network efficiency 99% in the cells edge.
Keywords—Vehicular Ad-Hoc networks; ITS; clustering;
overlapping area; handover; ICH
I. INTRODUCTION
This template, Vehicular Ad-hoc Networks (VANETs) is a
sub-part of mobile Ad-hoc networks (MANETs). The main
idea of VANETs is to establish communication between
vehicles for the personal safety of the vehicle’s occupants.
VANETs has two main types of communication: 1) vehicle to
vehicle (V2V), which allows vehicles to communicate between
others in point to point link by using IEEE802.11p standard
protocol. The advantages of this type are free of cost, no
infrastructure required and easy network deployment.
However, it triggers some issues when there are an insufficient
number of vehicles, which result in disconnect problem and
packet loss [1], [2]; 2) vehicle to infrastructure (V2I), which
solves this issue by making sure that the vehicles are directly
connected to the base station (BS). BS coverage is large
because the higher transmission range decreases disconnect
problem [3], [4]. However, there are still some issues that arise
in this type, such as cost, difficult deployment network and
network load. All of the above issues result from high vehicle
mobility. High speed of vehicles causes a change in topology,
which results in an unstable network. Therefore, clustering is
used to reduce the above issues by combining vehicles in a
group called cluster. Cluster means connecting a number of
vehicles that are in the same transmission range. One of these
vehicles is called cluster-head (CH) and the remaining vehicles
are called cluster-members (CMs), with the CH responsible for
managing intra and inter-cluster communication [5]. The
benefit of clustering enhancement network performance is that
it reduces connection congestion at the base-stations in the
network. Nevertheless, vehicle mobility is still the main
challenge in the clustering according to [6]–[9]. Most of the
previous studies focused on reducing the effect of mobility by
increasing cluster stability since VANETs is sub-part of
MANETs. However, although the maximum nodes speed are 8
km/h [10], the handover between neighboring base-stations
(BS) in MANETs is a big challenge. Therefore, handover has
become a huge challenge in VANETs. According to the
National Speed Limits of Malaysia, the speed limit in urban
areas is 90 km/h. In addition, according to local cellular
networks in Malaysia, the average coverage area of LTE-BS in
the city is between 300 and 400 meters, which leads to vehicles
passing from one BS to another in short time duration,
resulting in more vehicle information required during
handover. Therefore, this paper has proposed a new method to
solve the handover in the overlapping area, a method called
Intelligent Cluster-Head (ICH). This paper is organized as
follows; section II is focused on handover problem, section III
described previous work related to a heterogeneous network,
section IV describes the new method (ICH) and theoretical
analysis, section V presents simulation and result analysis,
section VI presents the conclusion and future work.
The introduction should briefly place the study in a broad
context and highlight why it is important. It should define the
purpose of the work and its significance. The current state of
the research field should be reviewed carefully, and key
publications cited. Please highlight controversial and diverging
hypotheses when necessary. Finally, briefly mention the main
aim of the work and highlight the principal conclusions. As far
as possible, please keep the introduction comprehensible to
scientists outside your particular field of research. References
should be numbered in order of appearance and indicated by a
numeral or numerals in square brackets, e.g., [1] or [2,3], or
[4–6]. See the end of the document for further details on
references.
*Corresponding Author

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II. HANDOVER PROBLEM STATEMENT
This section discussed the handover problems in VANETs.
Handover, which has been studied in cellular networks, occurs
in the area between two neighbors BSs known as overlapping
area [24]. This area resulted from overlap in the transmission
range of both BSs and the signal in this area is weak because of
interference in the frequencies of neighbor BSs, as shown in
Fig. 1. Interference occurs between two neighbor BSs in the
mobile cellular network, as proposed in [25]. Based on a
literature review, no previous work has focused on handovers
that occur in the overlapping area in the clustering of VANETs.
Handover problem in clustering of VANETs is a more serious
problem than in mobile devices because vehicles have ten
times higher speed than mobile devices according to [10].
Vehicles in the overlapping area received two frequencies, one
frequency from each BS, therefore vehicles are confused about
sending its information to which base-station, while at the
same time, the signal in this area has become weaker due to
interference frequencies [25]. Three reasons why the handover
problem occurs more frequently in VANETs is because
vehicles are moving in high mobility, the vehicles are capable
to move quickly from one BS to another, and vehicles require
link established when moving, which cause increased handover
in the network. According to Malaysian local cellular
networks, the transmission range of BS in the urban city is
limited so as to reduce the effect on people’s health, and this
has resulted in a high number of BSs, which is another reason
to increase handover in the city. The use of clustering in this
research has led to handover becoming a serious problem
because communication with BS is done by cluster-head. In
addition, the information that is sent to BSs consists of both
CH and its CMs information, which may cause loss of cluster
information when CHs is in the overlapping area. This is
another reason that motivates us to solve this problem. Fig. 2
shows the handover problem in the overlapping area of
clustering in VANETs.
From Fig. 2, CH2 is in the overlapping area, therefore it
received two weak signals from two neighbor base-stations.
Thus, during the handover with CH 2, information of cluster is
lost. The proposed method aimed to solve the above problem
by using intelligent cluster-head (ICH) as discussed in the next
section.
Fig. 1. Interference between Two BSs in the Mobile Network [25].
Fig. 2. Handover Problem in the Overlapping Area of Clustering in
VANETs.
III. RELATED WORKS
This part introduced previous works that used clustering
with cellular networks (heterogeneous networks) in VANETs.
The main challenge in this area is high vehicle mobility that
results in a dynamic topology change. This has raised several
issues, which are the stability of the cluster, overhead, delay,
and disconnect problem. In previous work, [11] proposed
centralized clustering-based hybrid vehicular networking
architecture (CC-HVNA) that combines both IEEE 802.11p
and LTE in VANETs to enhance data dissemination by
creating roadside units (RSUs) or BS to elect and form a
cluster. This method resulted in improved delay and packet
delivery ratio (PDR). The authors in [12] proposed hierarchical
cluster-based location service in city environments (HCBLS) to
reduce overhead and increase cluster stability. Overhead is
reduced by reducing the update location costs. Stability is
enhanced by the selection of vehicle in the centric of
neighbor’s vehicles, known as CH. The outcome of this
method is reduced location updates and increased cluster
lifetime. In previous work, [13] proposed a novel multi-hop
moving zone (MMZ) clustering scheme CH selection based on
average relative speed, relative distance, and link life. The
result of this method is increased CH lifetime and reduced
delay. Moreover, authors in [14] proposed a new Vehicular
Cloud (VC) model to enhance data dissemination by using
LTE with IEEE802.11p, leading to increased PDR and reduced
delay. Other authors in [15] proposed intelligent naïve
Bayesian probabilistic estimation practice for traffic flow to
form a stable clustering in VANET (ANTSC) algorithm to
increase cluster stability by selected cluster head from the lane
that has the heaviest traffic flow. In addition, authors in [16]
proposed a novel destination and interest-aware clustering
(DIAC) mechanism to reduce link failures between vehicles
and LTE network based on the vehicle having the highest link-
quality becoming the CH. The authors in [17] proposed a
hybrid vehicular multi-hop algorithm for stable clustering
(VMaSC) with LTE and IEEE802.11p multi-hop clustering.
LTE was used to increase PDR and reduce delay, while
VMaSC was used to form a stable cluster by selecting CH
based on the relative speed of vehicles in the same
transmission range (TR). The combination of VMaSC with

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LET in a hybrid network, known as (VMaSC -LTE), was
intended to reduce load at BS by reducing the number of
clusters in the merge mechanism. However, while reduction in
the number of clusters will reduce load at BS, the handover
problem remains in the overlapping area. Other previous works
focused on the use of gateway (GW) to reduce the load at BSs
by a reduced number of CHs in the network. The GW is a
normal node has two types based on the location of GW. The
first type is the GW that is positioned between more than one
CHs. This type of GW is used to send the CH information to
other CHs that are within its transmission range with the aim to
make each CH know about the neighboring CHs [18]–[20].
However, these CHs are still connected to the BSs even though
GW is available. The second type of GW is the GW has a
location at the beginning and end of the transmission range of
CH. This type is not used to exchange information between
CHs but is responsible for inter-cluster communication and
used to inform its CH about new neighbor CH for merge
mechanism [21]. The main goal of both types of GW is to
achieve merge mechanism to merge several CHs in one CH to
decrease the number of CH in the network according to a
specific condition. The disadvantage of GW is that this re-
broadcast caused flooding in the network. However, most
researches used GW in multi-hop to increase cluster scalability
and reduce the number of CH in the network. There is no
procedure to select GW based only on the location of the node,
therefore more than one GWs between two CHs caused more
flooding and only one GW can do the same work of all the
GWs. The concept of relay node (RN) is that a normal node is
used to rebroadcast CH message to reach all CMs according to
[22], [23]. The RN also caused flooding in the network. None
of the previous related works have focused on handover
problem that occurs in the overlapping area during using
clustering in VANETs, therefore this study has proposed a new
method call Intelligent Cluster-Head (ICH) to solve this
problem. The concept of ICH is completely different from GW
and RN. Table I shows the difference between GW, RN, and
ICH. Summary of related works is presented in Table II.
IV. PROPOSED METHOD
This section discusses the proposed new method to solve
the handover problem that occurs after cluster formation
mentioned in the previous section. The aim of this new
method, known as Intelligent Cluster-Head (ICH), is to control
the connection link between CHs as discussed in section (C).
A. Features of ICH are
 ICH works as a controller on CHs and has the capability
to move connection between CH and BS from one CH
to another CH, thereby reserving signal strength (RSS)
of CHs to prevent handover in the overlapping area
because the proposed method can control on CHs by
changing connection from CH has weak signal to
another CH has good signal from BS.
 ICH is not a broadcast beacon that CHs use to broadcast
for CMs to reduce flooding in the networks. However,
ICH checks RSS in the beacons and when RSS of one
CHs becomes weak, the ICH sends a notification to this
CH about moving the connection to another CH during
ICH to guarantee the information of vehicles in the CH
that has weak RSS is not consumed by overhead.
 ICH reduced the number of up-links between CH and
BS by allowing only one CH to communicate with BS,
and another CH sends its vehicle information during
ICH to the CH that has a connection with BS. With this
method, the number of up-link connections is reduced
by half as compared to that available in all previous
methods that used a heterogeneous network.
 ICH calculated dynamic threshold speed for both
clusters according to simple Equation. ICH elected in
accurate method. The details of this point are presented
in the next sub-section.
B. Elected ICH
Should note, in this study clusters formation and CH
election based on same method used in VMaSC-1hop in [17].
This study focuses on electing ICH after clusters formation and
CH elected. When a vehicle received two beacon messages
from different CHs, it does not change its state directly like
GW. This vehicle checks the direction of new CH; if it is in the
opposite direction, the vehicle drops the beacon and continues
as CM in its original CH. However, if a beacon message is in
the same direction, there are two cases according to Fig. 3.
In the first case, if the original CH (OCH) is in front of
new CH (NCH), the vehicle that received a new beacon from
NCH first checks the NCH speed; if the speed is less than OCH
speed, the vehicle drops beacon and continues as CM.
However, if NCH has a higher speed than OCH speed, the
vehicle calculates dynamic threshold speed (Dthr) from
Equation (1) and (2), then calculates the speed difference
between NCH and OCH according to Equation (3). Table III
shows the symbols of this paper.
     (1)
     (2)
     (3)
Fig. 3. Two Cases of CH.

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TABLE. I. DIFFERENCE BETWEEN GW, RN AND ICH
NO.
GW [18]–[21]
RN [22], [23]
Proposed ICH
1
Broadcast beacon and merge clusters
Only for broadcast beacon
Controller by moving connection link between CHs based
on RSS
2
Increased flooding in the network
Increased flooding in the network
Avoid flooding beacon problem
3
Reduced number of up-link if merge occur
Does not reduce the number of up-link
Reduce the number of up-link without need for merge
mechanism
4
Increased network scalability
Not did
Increased network scalability
5
Elected based on location or CH elect GW
CH elect RN
Elected according to a special procedure as shown in
section (B)
6
Not used
Not used
Used DDthr and DSthr to increase link lifetime between
CHs
7
More than one in each CH or between CHs
More than one in each CH
Only one between CHs
TABLE. II. SUMMARY OF RELATED WORKS
Ref.
Method
Problem
Domain
Outcome
Solve handover
problem
[11]
CC-HVNA
 Data dissemination
Highway
 Reduce Delay.
 Increase PDR.
NA
[12]
HCBLS
 Overhead.
 Stability
Urban
 Increase cluster lifetime.
 Reduce location update.
NA
[13]
MMZ
 Overhead
Highway
 Increase CH lifetime.
 Reduce delay
NA
[14]
VC
 Data dissemination
NA
 Increase PDR.
 Reduce delay.
NA
[16]
DIAC
 Link Failures
Urban
 Increase CH and CM duration.
 Reduce overhead.
 Increase PDR.
NA
[17]
VMaSC
 Stability
 Overhead
Highway
 Increase CH duration.
 Reduce the number of cluster in the network.
 Increase PDR.
 Reduce delay.
NA
TABLE. III. LIST OF SYMBOLS
NO.
Symbol
Description
NO.
Symbol
Description
1
OCH
Original cluster-head
13
LLTO,I
Link lifetime between OCH and ICH
2
NCH
New cluster-head
14
LLTN,I
Link lifetime between NCH and ICH
3
DthrO
Dynamic threshold speed of OCH
15
∆DO,N
The relative distance between OCH and NCH
4
DthrN
Dynamic threshold speed of NCH
16
PO
Position of OCH
5
VS
Vehicle speed
17
PI
Position of ICH
6
DCHs
Different CH speed
18
PN
Position of NCH
7
∆DCH,CM
The relative distance between CH and CM
19
∆VO,N
The relative speed between OCH and NCH
8
∆VCH,CM
The relative speed between CH and CM
20
VO
Speed of OCH
9
VCH
Speed of CH
21
VI
Speed of ICH
10
VCM
Speed of CM
22
VN
Speed of NCH
11
LLTCH,CM
Link lifetime between CH and its CM
23
TRO
Transmission range of OCH
12
LLTO,N
Link lifetime between OCH and NCH
24
TRI
Transmission range of ICH

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When the difference in speed between OCH and NCH is
less than dynamic threshold speed according to Equation (4),
the vehicle sends message to OCH that contains all previous
details. The OCH then checks how many vehicles have
received beacon message from NCH, then the Competing
vehicles be made ICH (CICH); if there is only one vehicle, the
CH sends a confirmation message to the vehicle and the
vehicle becomes ICH. If there is more than one vehicle
proposed to be ICH, the OCH calculates the different dynamic
threshold for each vehicle according to Equation (5). Vehicles
with low different dynamic threshold speed, distance near to
the half of transmission range (TR) become ICH. The
remaining CICH vehicles are arranged in the table ranged from
low different dynamic threshold speed to high, with the benefit
that when ICH loses connection in any way, the vehicle in the
second row of the table directly becomes ICH in order to not
repeat the process again for more flexibility in the network.
   (4)
     (5)
In the second case,
the vehicle’s original CH (OCH)
backs off new CH (NCH). The vehicle that received a new
beacon from NCH first checks NCH speed, and if this speed
is greater than OCH speed, the vehicle drops the beacon and
continues as CM. However, if NCH has a lower speed than
OCH speed, the vehicle calculates dynamic threshold speed
(Dthr) from Equation (1) and (2), then calculates different
speed between NCH and OCH according to Equation (6).
The same step above is used for Equation (4) and (5).
    
(6)
In the above cases, in this study, assume the vehicle that
received a new beacon from another CH belongs to the
OCH. However, if vehicles belong to NCH, the same above
cases occur but the main difference is that validation will be
with the value of NCH. This means that in all cases, the
validation is done with the value of CH that owned the ICH.
Fig. 4 shows the flowchart for elected ICH in both cases.
Fig. 4. Flowchart of ICH Election Process.

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C. Solve Handover Problem by Applying ICH
Method
This section introduced how ICH manages neighbor
clusters and changes up-link from one CH to another to solve
the handover problem in the overlapping area. After CH sends
a confirmation message to the proposed vehicle that has high
qualification according to the previous section, the vehicle
changes its state from CM to ICH then informs another cluster
of this change. ICH begins to listen to both messages coming
from CHs, and this message has CH-ID, direction of CH, speed
of CH, number of CMs in the CH, different relative speed
between CH and each CM, different relative distance between
CH and its CMs, location of all clusters (location of each CM
in addition to location of CH itself) and RSS of CH. The ICH
compares the RSS of both CHs, and the CH having the highest
RSS sends vehicle information for both clusters to the BS,
while the CH that has low RSS sends its cluster information
directly by using IEEE802.11p standard to ICH. The ICH
sends this information to CH having the highest RSS. During
this process, the CH that is connected in the BS remains
connected in the BS until it has received two RSS from two
BSs (this means the CH has arrived at the overlapping area).
The CH then sends a weak signal message to ICH to change
uplink connection with the BS to another CH in order not to
lose vehicles’ information. When ICH received a weak signal
from CH, the ICH sends a message to another CH to establish a
link with the BS. The ICH sends vehicle information of CH
having two signals to another cluster, and then another cluster
begins to send information to the BS while CH that received
two signals disconnects the uplink with BS. Fig. 5 shows how
ICH works.
As shown in Fig. 5, CH 2 received two signals because it is
in the overlapping area. Thus, CH2 sends a weak signal
message to ICH, which then sends a message to CH 1 to
establish a link with the BS to send vehicle information. After
the link has been established, the ICH sends CH 2 information
to CH1, which is then sent to BS. By using ICH, the handover
problem that occurs in the overlapping area is solved. Also, the
use of ICH reduced the number of up-link connections with the
BS, thereby increasing the cluster stability in the network.
Fig. 6 shows the flowchart of vehicles that work as ICH.
Based on previous work [26], the LLT between CH and
CM is collected from the following equation.
     (7)
      (8)
Collected LLT between CH and CM has two cases
according to the following:
1)
First case:
When CM is in back of CH, LLT is
collected according to Equation (9) in [26]
    
󰇛󰇜 (9)
2)
Second case
:
When CM is in front of CH, LLT is
collected according to Equation (10) in [26].
    
󰇛󰇜 (10)
Fig. 5. Work of Intelligent Cluster-Head (ICH).
In this method, LLT is collected between two CHs during
ICH. Also, there are two cases to collect LLT according to
Fig. 3. The total LLT between OCH and NCH in this study was
calculated according to Equation (11), while the different
distance and different velocity were calculated according to
Equation (12) and (13), respectively.
     (11)
    (12)
      (13)
3)
The first case according to Fig. 3: each case has two
LLTs, one between OCH and ICH, while another LLT is
between NCH and ICH. This means this method that the ICH
must be in front of one CH and behind another CH. In Fig. 3,
in this study, assume ICH belongs to OCH, only in both cases
the purpose is to validate with the value of OCH only. The
same scenario applies when ICH belongs to NCH exactly but
validated with the value of NCH. According to Fig. 3, the ICH
is behind OCH; therefore the LLT is collected according to
Equation (14). In the same case where
the ICH is in front of
NCH, the LLT is collected according to Equation (15).
When ICH is behind OCH, LLT is collected according
to Equations (8), (9) and (10).
    
󰇛󰇜 (14)
   
󰇛󰇜 (15)
To get the total LLT between two CHs (OCH and NCH),
substitute Equations (14) and (15) in Equation (11).
   
󰇛󰇜
󰇛󰇜 (16)
Simplify equation (16) to get the best equation to collect
LLT between two CHs in Equation (17).

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      
󰇛 󰇜   
󰇛󰇜
 
󰇛 󰇜 
󰇛󰇜
󰇛󰇜     󰇛 󰇜  󰇛 󰇜
󰇛󰇜  󰇛󰇜

󰇛󰇜󰇛󰇜 (17)
4) The second case according to Fig. 3: this case is
different than other cases in that the signals are based on the
location of ICH according to OCH and NCH as shown in
Equation (18).
   
󰇛󰇜
󰇛󰇜 (18)
D. Theoretical Analysis and a Numerical Example
Based on the real-data collected from local cellular
networks in Batu Pahat, Johor, Malaysia, the transmission
range of LTE-base-station is between 300 to 400 meters.
Therefore, there are many BSs on the road, which leads to a lot
of overlapping areas that resulted in more handovers as
vehicles move on the road. Handover caused serious problems,
especially in clustering, because each cluster represents the CH
of each vehicle, and passing CH in the overlapping area caused
loss of all CMs information resulted from handover between
two BSs. [17] proposed VMaSC-LTE that is closest to the idea
of this study, where the load on the BS is reduced due to a
number of clusters in the network. However, reduction in the
number of clusters will reduce load at BS but not solve
handover problem because the remaining clusters still have a
handover. Also, there has been no focus on the overlapping
area. In this paper, we proposed ICH to solve handover
problems by positioning the ICH at the end of clusters-
transmission range. Thus, the front CH that received two
signals from two different BSs is directed to stop sending
vehicle information to the BS in order to not lose its cluster
information and sends this information to ICH and then to
another CH that is not in the overlapping area. Also, ICH
reduced uplink by half because every two clusters that have
ICH use only one uplink to connect both clusters in the BS.
This is because of the use of IEEE802.11p protocol to connect
inter and intra cluster and this protocol has data rate 27 Mbps
according to [27]. This study focuses on broadcast safety
message that has a size between (512 and 1000) byte according
to [10], [14], [17], [28], therefore the link between CH and BS
can send both CHs information during IEEE502.11p. For
example, if each CH has a maximum number of CMs, this
means 20 CMs according to [29], therefore the total number of
both clusters within the CHs becomes 42 vehicles. According
to above, each vehicle sends safety message 1000 bytes in size,
therefore the total size of safety message for both clusters
become (42x1000= 42,000 bytes. Divided by 1000 to convert
to KB, the size becomes 42 Kbps and the link can send up to
27 Mbps). Also, a reduced number of up-link results in reduced
overhead cost and increased cluster stability in the network.
Since VMaSC-LTE is used in highway scenario, in order to
evaluate this method with VMaSC-LTE, the idea of this
method was applied in this paper, scenario in the numerical
example.
Fig. 6. Flowchart of Vehicles that Work as ICH.

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If assumed length of road to be 10 km in urban Batu Pahat,
Johor, Malaysia, and number of vehicles (N-V) to be 100
according to real-data of local cellular network in Batu Pahat,
the TR of BS 300 m, the number of BSs (N-BS) is closer to 33
BS according to the real-data collected from local cellular
networks. This resulted in 32 overlapping area (OA), the
number of CMs (N-CMs) in each cluster is 20; therefore the
total number of CHs (N-CHS) in this road is 5. These clusters
in VMaSC-LTE have handover (HO) in each overlapping area.
Therefore, a number of handovers in VMaSC-LTE are
32x5x20 = 3200 handovers for total cluster according to the
number of CMs in each cluster over a 10 km road from 100
vehicles. However, in this method, no handover occurs in the
clusters having ICH, but the handover occurs if the cluster does
not have ICH. However, most of the clusters in proposed
method have ICH because of high vehicle density in the urban
area, especially in Batu Pahat city. From the above example
and because the ICH connects only two CHs, in the above
example one of five CH has handover in the overlapping area.
Therefore, the number of packets lost in this cluster is
calculated according to 32x1x20= 640 handover in the network
on the same road.
As shown in Fig. 7(A), there is no handover in the
overlapping area because ICH changed the up-link when CH 2
received two signals from BS1 and BS2. However, in
Fig. 7(B), the CH2 has no other choice than to send its cluster
information, therefore the probability of handover occurrence
is high. The number of handovers increases as road length and
number of vehicles on the road increases. Table IV shows the
result of a numerical example.
Fig. 7. Illustration of the difference between ICH and VMaSC-LTE Methods.
TABLE. IV. RESULT OF A NUMERICAL EXAMPLE.
Method
Road
N-V
N-CH
N-BS
OA
HO
VMaSC-LTE [17]
10km
100
5
33
32
3200
ICH
10km
100
5
33
32
640
V. SIMULATION MODELING
In this section, evaluated and validated ICH method with
VMaSC-1hop method [17]. The evaluation was done by
applying the concept of VMaSC-1hop on the scenario.
VMaSC-1hop method has been selected for evaluation because
it is close to the proposed idea. The VMaSC-1hop used GW to
merge clusters to reduce load at BSs, which consist of packet
loss, packet delivery ratio, disconnect problem and number of
uplink connection. Unfortunately, this method did not discuss
the handover problem that occurs in the overlapping area.
Therefore, the proposed method reduces the load at BSs in the
overlapping area. Both methods are applied by using
MATLAB-a 2018 in the simulation. The simulation parameters
used in this study are shown in Table V.
A. Performance Metrics
 Packet loss: This is defined as the number of CHs that
failed in sending the cluster information to the BSs. In
this study, the packet loss is measured in the
overlapping area (cell edges) only. Also, the
information related to CHs loss in this area consists of
information of CH and its CMs. The packet loss
increased when the number of clusters increased and the
number of CMs in each CH increased.
 Packet delivery ratio (PDR): This is defined as the
number of CHs that successfully sent its cluster
information to the BS during cell edge. The PDR
increased when the number of CH that successfully sent
its cluster information in the cell edge increased and the
number of CMs in each CH increased.
 A number of disconnections: It is the number of CH that
lost connection with BS during cell edges from the total
number of CH that successfully connects with the BS in
this area.
 Network efficiency: The average ratio of a number of
packet loss to the total number of PDR in the cells edge.
Increased percentage of packet loss during cells edge
result in reduced network efficiency.
B. Performance Comparison between ICH Method and
VMaSC-1hop Method
Table VI shows the ICH method has less packet loss than
VMaSC-1hop method in cells edge because of the ICH transfer
communication up link from CH that received two signals from
different BSs to another CH. By this process, the number of
packet loss is reduced. The VMaSC method used GW to make
the connection between neighbors’ CHs for merge mechanism
without any permission to move up link connection because it
is a normal node; therefore, the packet loss occurs in the cells
edge. From the table, the ICH method also has packet loss, but
much less than VMaSC method. The packet loss in the
proposed method results from CH that had no neighbor CH.
Therefore, in this case, the packet loss occurred in ICH
method. The average percentage of packet loss at a cell edge in
the ICH method and VMaSC-1hop method is 0.8% and 84%,
respectively.
Fig. 8 shows the ICH method has higher packet delivery
ratio than the previous method, and the reason is that proposed
method can deliver packets even in cell edge by changing
uplink from CH that has weak signal or confused single to CH
that has good signal or only one signal. Thus, the percentage of
PDR in proposed method is greater than the previous method.
The average percentage of PDR at the cell edge in ICH method
and VMaSC-1hop method is 99% and 15%, respectively.

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TABLE. V. SIMULATION PARAMETERS
Parameters
Value
Simulation time
300 s in each run
MAC protocol
IEEE 802.11p
Transmission range
300 m
Number of vehicles
100,200,300,400,575
Road length
17.8 km
Number of lanes in the road
3
Length of car
3 m
Maximum lane speed
10-100 km/h
Number of hops
One hope
maximum number of CMs in each CH
20
Number of iterations
100
Number of runs
10
TABLE. VI. NUMBER OF PACKET LOSS IN BOTH METHODS IN THE CELLS
EDGE
Number of Vehicles
Proposed
VMaSC-1hop [17]
100 Vehicles
181
6920
200 Vehicles
167
16422
300 Vehicles
151
25314
400 Vehicles
190
34466
575 Vehicles
149
50467
The average number of packet loss
in the cell edge
167.60
26717.8
Fig. 9 shows the number of disconnect in the cells edge
between ICH method and VMaSC-1hop method. The ICH
method resulted in fewer disconnect than the previous method
because the ICH allows CH to connect in the BS, even the CH
in the cell edge, while the previous method during cell edge
has disconnect because the CH received two signals from
different BS and GW cannot transfer uplink connection to
neighbor CH.
Fig. 8. PDR in the Cells Edge.
Fig. 9. Disconnect Problem During Cells Edge.
Fig. 10. Network Efficiency in the Cells Edge.
Fig. 10 shows the network efficiency of ICH and VMaSC-
1hop method. From the figure, the ICH method results in a
higher percentage of network efficiency than VMaSC-1hop
method because ICH method has less percentage of packet
loss, less percentage of disconnect problem and a higher
percentage of PDR than VMaSC-1hop method. Therefore, the
network efficiency in ICH method is higher than in VMaSC-
1hop method. The average percentage of network efficiency in
the ICH method and VMaSC-1hop method is 96% and 70%,
respectively.
VI. CONCLUSION
This paper has proposed a novel method known as
Intelligent Cluster-Head to solve the handover problem that
occurs in the overlapping area (cell edge) when the cluster is
passed from one BS to another neighbor BS. ICH is a
controller vehicle that controls a neighbor’s CHs and specifies
the cluster having the higher RSS to send vehicle information
of both clusters to BS. Also, ICH has the ability to change
uplink from one cluster to another to solve handover problem
of CH receiving two signals from different BSs in direct

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contact with ICH, and the ICH then changes the uplink to
another cluster. The evaluation was done by using MATLAB
software during evaluating the ICH method with the concept of
VMaSC-1hop and the result shows the ICH method and
VMaSC-1hop have an average percentage of packet loss of
0.8% and 84%, respectively. The percentage of PDR in ICH
method and VMaSC-1hop is 99% and 15%, respectively. The
number of disconnect in ICH method is less than VMaSC-1hop
method and the network efficiency in ICH method VMaSC-
1hop method is 96% and 70%, respectively. In future work,
will analyse and evaluate the effect of delay and overhead
when using the proposed method. Also, we will apply this
method on a highway scenario.
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