Improved Performance of LEACH for WSN Using Precise Number of Cluster-Head and Better Cluster-Head Selection

IJSRD - International Journal for Scientific Research & Development| Vol. 1, Issue 2, 2013 | ISSN (online): 2321-0613
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Improved Performance of LEACH for WSN Using Precise Number of
Cluster-Head and Better Cluster-Head Selection
Jay R. Bhadeshiya1
1
Electronics & Communication Department,
1
Atmiya Institute of Technology & Science, Rajkot, GTU, Gujarat, India
Abstract – Wireless microsensor systems will facilitate the
reliable monitoring of a variety of environments for several
applications like as civil and military. In this paper, we look
at modified LEACH protocol. This paper presents a new
approach to clustering wireless sensor networks and
determining cluster heads. LEACH is a hierarchical cluster
algorithm in which Cluster-Heads are randomly selected
from the nodes. Here, I apply new approach for selection of
Cluster-Head according to their initial and residual energy
of all the nodes and according to their initial and residual
energy nodes are eligible for cluster head in the next round.
Results of new approach of LEACH protocol compared with
Conventional routing protocol.
Keywords: Clustering, Energy Consumption, Lifetime,
Routing, Wireless sensor network.
I. INTRODUCTION
The basic idea of anytime and anywhere computing leads to
the new field called mobile computing. The advances in the
wireless technology are also one of the major growths of
mobile computing. But here in this ubiquitous computing
environment we can’t follow the normal architecture and
protocols which have been used in the fixed network due to
its battery powered devices involved in the computing and
transmission of the data. The advancement in these
miniature computing model and wireless transmission
techniques lead to the development of the wireless sensor
networks. Sensor networks are needed in the applications
like environment monitoring, industrial control units,
military applications and in the context aware computing
environments [1].
Since the entire sensor nodes are battery powered
devices, energy consumption of nodes during
transmission or reception of packets affects the life-time of
the entire network. To make routing, an energy efficient
one, number of protocols like LEACH and PEGASIS were
developed.
Though they have achieved efficiency by more than 8
times than the previous protocols, still these are used for
only static sensor nodes. In this paper we have proposed a
novel approach to develop an energy efficient routing for
the mobile sensor networks [4]. LEACH uses the following
clustering-model: Some of the nodes are elect themselves as
cluster-heads. These cluster-heads collect data from other
node and aggregated data transfer to the Base Station. Since
data transfers to the base station require much energy. The
nodes take turns with the transmission – the position of
cluster head is rotate. For balanced energy consumption all
nodes have rotation for the cluster-heads. Hence to a longer
lifetime of the network. Modification of LEACH’s cluster
head selection algorithm to reduce energy consumption.
II. BACKGROUNGD
To meet the distinctive requirements of wireless
sensor networks, we established Low Energy Adaptive
Clustering Hierarchy , application-specific protocol
architecture. The task that sensor networks carry is
observing of a remote environment. Since individual nodes’
data are often interrelated in a sensor network, the end user
does not necessitate all the data; rather, the end user needs a
high-level function of the data that describes the actions
occurring in the environment. Because the very strong
correlation is essential between data signals from nodes
situated near to one another, we chose to use a clustering
arrangement as the basis for Low Energy Adaptive
Clustering Hierarchy. This allows all data from nodes within
the cluster to be process locally, sinking the data set that
needs to be transmitted to the end user. Data aggregation
methods can be used to combine several interrelated data
signals into a smaller set of information that maintains the
useful data (i.e., the information content) of the original
signals. Therefore, less amount of actual data requires to be
transmitted from the cluster to the base station (BS) [3][5].
For the sensor nodes, we assume that all nodes can
transmit with enough power to reach the Base Station if
needed, that the nodes can use power control to vary the
amount of transmit power, and that each node has support
different MAC protocols and perform signal processing
functions. For the network, we use a model where nodes
always have data to send to the end user and nodes located
close to each other have correlated data. Although Low
Energy Adaptive Clustering Hierarchy is optimized for this
situation, it will continue to work if it were not true. The
nodes sort out themselves into local clusters, with one node
acting as the cluster head (CH) [6][7].
All non-cluster head nodes send their data to the CH,
while the CH node receives data from all the cluster
members, performs signal processing functions on the
received data using different data aggregation methods, and
transmits data to the remote Base Station. So, being a cluster
head (CH) a sensor node is much more energy demanding
than being a non-cluster head node. If the cluster heads were
get selected before, these nodes would rapidly use up their
limited energy & get exhausted. Once the cluster head has
no energy, it is no longer outfitted, and all the nodes that

Improved Performance of LEACH for WSN using precise number of Cluster-Head and Better Cluster-Head Selection
(IJSRD/Vol. 1/Issue 2/2013/0027)
All rights reserved by www.ijsrd.com
162
belong to the cluster lose their communication ability [2].
Thus, LEACH includes a totally randomized rotation of the
cluster head’s position, having the high-energy, among the
sensors to avoid exhausting the battery of any one sensor in
the network. In this way, the energy load of being a cluster
head is evenly distributed among the nodes. The operation
of LEACH is divided into rounds. Each round begins with a
set-up phase when the clusters are organized, followed by a
steady-state phase when data are transferred from the nodes
to the cluster head and on to the BS, as shown in fig 1.
Figure1:- Adaptive Clusters are formed during the Set-Up
Phase and Data Transfers Occur during the Steady-State
Phase
III. CLUSTER HEAD SELECTION ALGORITHMS
Low Energy Adaptive Clustering Hierarchy arranges &
makes clusters by using a distributed algorithm. In which
node can make self-determining decisions without any
centralized control. Their goal is to design an algorithm for
cluster formation, in which there are certain number of
clusters, k in each rounds. Low Energy Adaptive Clustering
Hierarchy operation provides a conception of round, with
every round there are set-up phase and steady-state phase
[9][12].
A. Set-up Phase
In case of set-up phase, each node decides whether or not
become a cluster head for current round. This decision based
on random number between 0 and 1,if the number is less
than a threshold T(n) in (1),the node become a cluster head
for the current round. A flowchart of this distributed cluster
formation algorithm is shown in Figure 3 [9][10].
(1)
Figure1:-Cluster head set up a TDMA schedule, this
schedule is transmit to all other node in the cluster.
Figure2:- Time Line Operation of Leach
Figure3:- Flow Chart of the Set-Up Phase of Leach
B. Steady State Phase
In the state the operation divides into the frames, where
nodes send their data to the cluster head at each once per
frame during their allocated slot shown in Figure 1.Each non
cluster head node can be turned off until the node’s
allocated transmission time. Cluster head receive all the data
from the node in the cluster.
When all the data has been received, cluster head node
performs signal processing functions to data into single
signal shown in Figure 4. This composite final signal is sent
to the BS. Figure. 2 shows the time line for one round of
LEACH [8][11].
Fig. 4: Flow Chart for Steady State Phase
IV. PROPOSED METHOD OF LEACH PROTOCOL
The number of cluster-head nodes is the prerequisite to
implement clustering, LEACH protocol has not given the
numerical computation method to determine the number of
cluster-head nodes explicitly.
The cluster-head Selection is depending on the
selection of random number from 0 to 1. If the threshold
value for the node is more than the random number then the
node can become a cluster-head for the current round.
Limiting the number of cluster heads per round or in other
words dividing the area into the finite number of grids. By
doing this we are controlling the energy distribution
between the nodes & making it even.
1 [ *mod(1/ )]( )
0 ,
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if n G
P r PT n
otherwise
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163
Here I have analyzed the cases with optimum number
of cluster-head.
A. Limiting Number of Cluster-Head to 4 & 5 Cluster-Head
In this case fixed 4 & 5 CH per round will announced
for cluster-head for current round in cluster rest of nodes in
the cluster will join them for the current round. In each
round cluster-head will be fixed 4 CH and 5 CH and all
other nodes in the cluster are cluster nodes. According to the
fixed number of cluster will improve the life span of the
cluster because in every round only 4 and 5 nodes will be
selected as cluster-head so rest of nodes transfer to data to
only those 4 and 5 CH. In the case of 5 CH less energy
require for transferred to data to base station so less energy
will require compared to 4 CH.
A. Limiting Number of Cluster-Head 4% & 5% Cluster-
Head
In this case fixed 4% & 5% CH of total nodes per
round will announced for cluster-head for current round in
cluster rest of nodes will join them. In this case only 4% and
5% of the all nodes will selected for cluster-head for the
current round and rest of nodes transfer data to those cluster-
head for the current round. In this case 5% CH less energy
require for transferred to data to base station so less energy
will require compared to 4% CH.
B. Modified LEACH
In this modified LEACH, Selection of cluster head is
based on initial and residual energy of the nodes. In each
round cluster head will be selected bases on the below
equation (2) and according to this equation (2) maximum
amount of energy nodes selected as cluster head for the
current round. Using this equation require less energy to
transmit data to the base station.
(2)
Where Eresidual is available energy of node, Einitnal is total
energy given to node at initial stage, Eavrage is total average
energy of all live nodes.
V. SIMULATION, EXPERIMENTAL RESULTS &
ANALYSIS
To validate the performance of proposed LEACH-sub-
CH protocol, we simulate the protocol and utilize a network
with 100 nodes randomly deployed between (x=0, y=0) and
(x=100, y=100) and base station at (50,175). The bandwidth
of channel is set to 1 Mb/s; each data message is 500 bytes
long. The initial power of all nodes is considered to be 2J
and duration of each round is 20s.
A. Optimum Number of Cluster-Head
In LEACH, the cluster formation algorithm was
created to confirm that the estimated number of clusters in
sensor network per round is k, a system parameter. We can
analytically determine the optimum value of k in LEACH
using the computation and communication models. Assume
that there are N nodes distributed uniformly in an M x M
region. If there are k clusters, there are on average N/k
nodes per cluster (one cluster head and (N/k)-1non-cluster
head nodes). Each cluster head scatters energy receiving
signals from the nodes, aggregating the signals, and
transmitting the aggregate signal to the base station.
B. For 4 & 5 Cluster-Head
Figure1:- shows the number of the alive nodes with
time in the network based on rounds. It can be seen that the
LEACH protocol has emerged that total data received at the
base station is more in 4 CH compare to LEACH. In Fig 4
total energy require for that transited data to the base station.
According to the Fig 5 and Fig 6 total received at base
station is nearby same but in the case of 5 CH less energy
will be require for transmitted data to base station.
Figure. 5: Comparison of LEACH & Maximum (4 CHs)
Round for Time Vs Number of Data at BS.
Round for Energy Vs Number of Data at BS.

164
In Fig 13 and Fig 14 shows that total data received at
station is more in 4 CH compare to the 5 CH and LEACH
but total life span of the network in case of 5 CH is better
than the 4 CH and LEACH.
Figure. 9: Comparison of Total Amount of Data Received
At BS for LEACH & 4 CHs-5CHs/Round - Number of
Simulation
Figure. 10: Comparison of Life Span of Network for
LEACH & 4 CHs-5 CHs/Round - Number Of Simulation
C. For 4% & 5% Cluster-Head
Figure 10 shows the number of the alive nodes with time in
the network based on rounds. It can be seen that the LEACH
protocol has emerged that total data received at the base
station is more in 4% CH compare to LEACH. In Fig 10
total energy require for that transited data to the base station.
According to the Fig 11 and Fig 12 total received at base
station is nearby same but in the case of 5% CH less energy
will be require for transmitted data to base station.
Figure. 11: Comparison of LEACH & Maximum (4% CHs)

165
In Fig 13 and Fig 14 shows that total data received at station
is more in 4% CH compare to the 5% CH and LEACH but
total life span of the network in case of 5% CH is better than
the 4% CH and LEACH.
At BS for LEACH & 4% CHs-5% CHs/Round - Number of
Simulation
LEACH & 4% CHs-5% CHs/Round - Number Of
Simulation
D. Modified LEACH
In Modified LEACH Cluster-Head selection based on the
initial and residual energy of the nodes. In this Modified
LEACH in each round cluster-head will be selected based
on intimal and residual energy of the nodes according to the
equation (2). Results prove that Modified LEACH work
better than the LEACH Protocol. In Fig 15 and Fig 16
shows that data transmitted at base station is more compare
to LEACH and also less energy will be require for that.
Figure. 17: Comparison of LEACH & Modified LEACH
Figure 18: Comparison of LEACH & Modified LEACH
In Fig 17 and Fig 18 shows that total data received at
station is more in Modified LEACH compare to LEACH

166
and total life span of the network in Modified LEACH better
than the LEACH.
At BS for LEACH & Modified LEACH Round - Number of
Simulation
LEACH & Modified LEACH/Round - Number Of
Simulation
VI. CONCLUSION
The Simulation shows that Modified LEACH based
on new approach for selection of Cluster-Head and overall
performance of modified LEACH is better than the
Conventional LEACH. Total data transmitted at the base
station is more and life span of the network is better than
LEACH. In this paper Modified LEACH indicates the
optimal number of cluster-heads in a network and considers
residual energy in the stage of cluster-heads selection and
modified LEACH can prolong lifetime and reduce the
energy consuming, it has better performance than LEACH
protocol
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Improved Performance of LEACH for WSN Using Precise Number of Cluster-Head and Better Cluster-Head Selection

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Improved Performance of LEACH for WSN Using Precise Number of Cluster-Head and Better Cluster-Head Selection