Comparison of Energy Efficient WSN in Coverage and Connectivity

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 04 Issue: 10 | Oct -2017 www.irjet.net p-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 839
Comparision of Energy Efficient WSN in Coverage and Connectivity
Bhumika Ingole 1, Arpita Chirde 2
1,2 Electronics & Communication Department, Tulsiramji Gaikwad Patil College of Engineering,
Nagpur, Maharashtra, India
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Abstract - Wireless Sensor network (WSN) comprises of
tiny sensor nodes with very limited initial energy and are
deployed in sensing area of particular interest to fetch
necessary environment data and sending it back to end user
via base station. One of the major issue in WSN is energy
efficient coverage in which major goal of routing protocol is
to observe every possible physical space without any loss of
data due to lack of energy or power in sensor node. Such
situation may occur due to over burden on nodes when
unbalanced clusters are formed leading to extra
communication overhead. In this Paper we are discussing
the comparison of LEACH & SEP protocols in terms of Packet
transmission, energy dissipation and number of Nodes alive
and stability period and we will discuss the advantage and
disadvantage of these protocols under various conditions.
Key Words: Wireless Sensor Network, Coverage,
Clustering, Routing Protocol, Stability period,
LEACH protocol, SEP protocol
1. INTRODUCTION
A wireless sensor network (WSN) consists of a collection
of low power, low cost, and autonomous sensor nodes,
which communicate among themselves through wireless
link only. Each sensor node is facilitated with multiple
power levels to transmit the data in wireless channel. Each
sensor node runs mostly by battery power. The constraint
imposed on WSN is due to less supply of energy A Wireless
Sensor Network (WSN) is a collection of tiny sensor nodes
which are interconnected by wireless communication
channels. Each sensor node is a small device that can
collect data from its surrounding area, carry out simple
computations and communicate with other sensors or
with the base station (BS).The nodes are deployed in a
monitoring field as shown in the following Figure 1.1 [1]
and each of them capture data and sends data back to the
base station or sink. Data are routed back to the sink by
following direct or multi-hop dedicated path. The base
station may communicate with the task manager via
Internet or satellite. The information flow in typical WSN
is explained in Figure 1.1. The design of WSN is influenced
by many factors such as initial energy, scalability,
production costs, sensing environment, and network
topology and power consumption of sensor nodes.
Therefore designing wireless sensor network is a very
challenging task when coverage along with network
lifetime is considered. There exit a tradeoff between
coverage and network lifetime because if we consider full
coverage then network lifetime get reduced and if we try
to increase network lifetime then coverage gets reduced.
The specified environment may be in the form of entire
deployment area, specific points in the deployment area,
or across certain region where there is some possibility of
breach. Based on these above criteria, coverage is
categorized into 3 types.
1) Area Coverage
2) Target Coverage
3) Barrier Coverage
• Area Coverage: It refers to observe the entire area. This
means, every single point in the given field of interest
must be coming under the sensing range of at least one
active sensor node [2]. Ideally, the number of active sensor
nodes are minimum even if the number of deployed
sensor nodes are quite high.
• Target Coverage: In this case, the targets are
represented as set of discrete points within the given field
of interest and each target or point must be covered by at
least one active sensor node[3], [4]. This type of coverage
is basically used in military applications.
• Barrier Coverage: It refers to observing the movement
of mobile objects that enter into the boundary of a given
field of interest or moving across the sensor field [5], [6].
Intrusion detection is an important application of barrier
coverage.
Figure 1.1: Information flow in wireless sensor network
In any wireless sensor network, sensor node consists of
four basic components, as shown in the following Figure
1.2, a sensing unit, a processing unit, a transceiver unit,
and a power unit. They may also have additional

application dependent components such as a location
finding system, power generator and mobilize.
Figure 1.2: The components of a wireless sensor node
Although many algorithms and protocols have
been proposed for traditional wireless adhoc networks
like MANET, they are not well suited for wireless sensor
networks because of the following differences between
wireless sensor networks and ad-hoc networks like
MANET
1) The number of wireless sensor nodes in a typical WSN
are much higher than the nodes in a simple ad-hoc
network.
2) Sensor nodes are densely deployed and the rate of node
failure is much higher mainly due to limited initial energy
at the time of deployment.
3) The topology of a WSN changes very frequently for
specific applications.
4) Sensor nodes mainly use a broadcast communication,
whereas most adhoc networks are using point to point
communications.
5) Wireless Sensor nodes are limited in energy,
computation and storage memory.
6) Absence of unique and global identification (ID’s)
because of the large amount of overhead and large number
of nodes taking part in WSN resulting in inability to
maintain database of sensor nodes.
2. REVIEW OF CLUSTERING ALGORITHMS FOR
WIRELESS SENSOR NETWORK
2.1. LEACH (Low Energy Adaptive Clustering Hierarchy)
LEACH is one of the most popular clustering algorithms.
The main idea behind leach is to form clusters based upon
the signal strength of the sensors. Some of the nodes are
randomly chosen as the cluster heads (CH) and a node is
assigned to the CH based upon the signal strength received
by that node from the CH. CHs have to do a lot more work
than the normal nodes, hence they dissipate a lot more
energy and may die quickly. In order to maintain a stable
network, CHs keep on rotating, in every round. So, a node
which had become CH may not get an opportunity to
become CH again before a set interval of time.
A node can become the cluster head for the current round
if its value is less than the threshold T(n) where T(n) is
given by –
P is the percentage of cluster heads, r is the rth round, G is
the set of nodes which are not cluster heads in the last 1/P
rounds.
Advantages:
 LEACH is completely distributed.
 LEACH does not require the control information
from the base station, and the nodes do not
require knowledge of the global network in order
for LEACH to operate.
 LEACH reduces communication energy by 8 times
as compare to direct transmission and minimum
transmission energy routing.
2.2. SEP (Stable Election Protocol)
SEP was an improvement over LEACH in the way that it
took into account the heterogeneity of networks. In SEP,
some of the high energy nodes are referred to as advanced
nodes and the probability of advanced nodes to become
CHs is more as compared to that of non-advanced nodes.
Advantage:
 SEP does not require any global knowledge of
energy at every election round.
Limitations:
 The drawback SEP method is that the election of
the cluster heads among the two type of nodes is
not dynamic, which results that the nodes that are
far away from the powerful nodes will die first.
2.3. DEEC (Distributed Energy Efficient Clustering)
In DEEC protocol all nodes use the initial and residual
energy level to define the cluster heads. DEEC estimate the
ideal value of network lifetime to compute the reference
energy that each node should expend during each round.
In a two-level heterogeneous network, where we have two
categories of nodes, m. N advanced nodes with initial
energy equal to Eo.(1+a) and (1 −m).N normal nodes,
where the initial energy is equal to Eo. Where a and m are
two variable which control the nodes percentage types

(advanced or normal) and the total initial energy in the
network Etotal.
 The value of Total Energy is given as
Etotal = N. (1−m).Eo+N.m.Eo. (1+a) (1)
 The average energy of rth round is set as follows
E(r) = 1 Etotal (1 −R) (2)
N
R denotes the total rounds of the network lifetime and is
defined as
EtotalR Eround (3)
ERound is the total energy dissipated in the network during
a round, is equal to:
ERound = L(2NEelec +NEDA + kEmpd4toBS+NEfsd2toCH)
k: number of clusters
EDA: data aggregation cost expended in the cluster heads
dtoBS: average distance between the cluster head and
the base station
dtoCH: average distance between the cluster members
and the cluster head.
Because we are assuming that the nodes are uniformly
distributed, we can get:
/ 2dtoCH M K
0.765 / 2dtoBS M
Advantages:
 DEEC does not require any global knowledge of
energy at every election round.
 Unlike SEP and LEACH DEEC can perform well in
multi-level Heterogeneous wireless network.
Limitations:
 Advanced nodes always penalize in the DEEC,
particularly when their residual energy reduced
and become in the range of the normal nodes. In
this position, the advanced nodes die rapidly than
the others.
3. ENERGY MODEL ANALYSIS
In this paper, we are analysing three protocols – LEACH,
SEP and DEEC-based on the energy dissipation model
shown in the following figure –
Fig -1: Energy dissipation diagram
For a particular node, the energy is dissipated because of
receiving and transmitting. The energy expanded in
transmitter to transmit k-bit message is given by –
ET (k,d) = (Eelec * k) + (Efs*k*d2)
if d<=d0
(Eelec * k) + (Emp*k*d4)
if d>d0
 Eelec is the energy dissipated to run the electronics
circuits
 k is the packet size
 Efs and Emp are the characteristics of the
transmitter amplifier
 d is the distance between the two communicating
ends
Energy dissipation to receive a k-bit message is given by-
ER(k) = Eelec* k
The values of radio characteristics are –
Eelec = 50 nJ/bit
Efs = 10 pJ/bit/m2
Emp = 0.0013pJ/bit/m4
In addition to above energy expansions, a CH also
dissipates energy because of data aggregation. The data
aggregation energy EDA has the value of 5nJ/bit/signal.
4. Simulation Results
We have carried out a number of experiments and used
them for the comparison of LEACH, SEP and DEEC for
various performance metrics. Simulation results on
MATLAB depict that DEEC has better stability period and
less energy dissipation per round.
A. Network Settings
We are using a 100*100 region having 100 sensor nodes
placed randomly. The probability of advanced nodes is

kept as 0.2, so the number of advanced nodes is 20. The
packet size is considered to be of 4000 bits. The various
parameter values taken for experiments are shown in the
following table –
Parameter Value
Eelec 50 nJ/bit
Efs 10 pJ/bit/m2
Emp 0.0013 pJ/bit/m4
EDA 5 nJ/bit/packet
E0 0.5 J
K 4000 bits
Kopt 3
Popt 0.1
N 100
A 1
M 0.2
D 30
Network Size 100*100
Base Station Location (50,50)
We have measured performance on the basis of following
measurements:
(i) Stability Period is the period (or round) up to which all
nodes are alive. This period lies between rounds 1 to the
round at which the first node dies.
(ii) Instability period is the period between the first dead
node and last dead node. This period should be kept as
small as possible.
(iii) Energy dissipation
(iv) Different values of heterogeneity.
Figure 2: Number of Nodes alive Vs Number of rounds
From the figure 1 it is clear that the DEEC is more stable
than the SEP and LEACH as the first node dead in DEEC
after LEACH and SEP shows stability period of DEEC is
prolong than the LEACH and SEP.
Table 1.Comparision table for LEACH, SEP and DEEC
Figure 3: Energy dissipation diagram of LEACH, SEP
and DEEC
Performance
Criteria
LEACH SEP DEEC
Heterogeneity
level
Not present Two Multilevel
Cluster
Stability
Lower than
SEP and
DEEC
Moderate High
Energy
Efficient
Low as
Compare to
SEP & DEEC
Moderate High
Cluster Head
Selection
Criteria
Based on
initial &
Residual
Energy
Based on
initial &
Residual
Energy
Based on
initial,
Residual &
Average
Energy of
Network
Network
Lifetime
Lower than
SEP and
DEEC
Moderate
Prolong
Network
Lifetime
than SEP
& LEACH

Figure 4: Number of Data packets transmitted to base
station Vs. Number of rounds.
We can see from the figure 4 that the packets transferred
to the base station are large in DEEC as compare to SEP
and LEACH.
5. CONCLUSION
We had compared the LEACH SEP and DEEC protocol
under various performances metric through simulation.
The performance of the three protocols are judged under
the various performance metric .Simulation results shows
that DEEC outperforms the two .The table (1) shows the
comparison of three protocols under various performance
metrics.
REFERENCES
[1] M. Cardei and D.-Z. Du, “Improving Wireless Sensor
Network Lifetime through Power Aware Organization”,
ACM Wireless Networks, Vol. 11, No. 3, 2005.
[2] M. Cardei, D. Mac Callum, X. Cheng, M. Min, X. Jia, D. Li
and D.- Z. Du, “Wireless Sensor Networks with Energy
Efficient Organization”, Journal of Interconnection
Networks, Vol. 3, No. 3-4, pp. 213-229, Dec. 2002.
[3] M. Cardei, M. Thai, Y. Li andW. Wu, “Energy-Efficient
Target Coverage in Wireless Sensor Networks”, Proc. of
IEEE INFOCOM, 2005.
[4] F. Akyidiz, Y. Sankara Subramaniam W. Su, and E.
Cayirci, "A survey on sensor networks", IEEE
Communication, August 2002.
[5] J. N. Al-Karaki and A. E. Kamal, "Routing techniques in
wireless sensor networks: a survey," IEEE Wireless
Communications, vol. 11, no. 6, pp. 6-28, Dec. 2004.
[6] L. Qing, Q. Zhu, M. Wang, "Design of a distributed
energy-efficient clustering algorithm for heterogeneous
wireless sensor networks". ELSEVIER, Computer
Communications 29, pp. 2230-2237, 2006.

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