This document summarizes and compares several hierarchical routing protocols for wireless sensor networks that aim to improve energy efficiency and increase network lifetime. It discusses Low-Energy Adaptive Clustering Hierarchy (LEACH), Energy LEACH (e-LEACH), Power-Efficient Gathering in Sensor Information Systems (PEGASIS), Threshold-sensitive Energy Efficient sensor Network (TEEN), and Hybrid Energy-Efficient Distributed clustering (HEED). It compares the protocols based on their concept, achieved network lifetime, energy efficiency, and drawbacks. LEACH uses random cluster head selection while e-LEACH selects heads based on residual energy. PEGASIS forms chains to reduce distances between nodes but has single point failures. TEEN

1. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
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AN ENERGY EFFICIENT PROTOCOL BASED STUDY OF
WSN TO INCREASE THE LIFETIME
Anjumol O N
Final Year MTech, Dept of Computer Science & Engineering, Sree Narayana Gurukulam College of Engineering,
Kerala, India
P.K.K Thampi
Associate Professor, Dept of Computer Science & Engineering, Sree Narayana Gurukulam College of Engineering,
Kerala, India
ABSTRACT
Wireless Sensor Network is an emerging area having wide applicability and deployment in coming era. They
can be used in different areas like industry, under water, health; etc.WSN is a network of sensor nodes, which can be
used for sensing or collecting physical as well as environmental information. Each node in the WSN is battery powered,
i.e. efficient energy management is more crucial issue in WSN. The energy dissipation of each and every node in the
network will affect their lifetime, in turn it will affect the lifetime of the entire network. So, in order to prevent this issue
and to maximize the entire lifetime of the network, efficient energy management techniques are necessary. In this paper,
different techniques to increase the lifetime of sensor network like Low Energy Adaptive Clustering Hierarchy
(LEACH), Energy LEACH, Power Efficient Gathering in Sensor Information System (PEGASIS),Threshold Sensitive
Energy Efficient Network (TEEN), Hybrid Energy Efficient Distributed Clustering (HEED) have been studied; which are
coming under the category of Hierarchical or clustering based protocol. These protocols are compared to evaluate their
advantages and disadvantages.
KEYWORDS: Clustering, e-LEACH, EER, HEED, LEACH, PEGASIS, TEEN, WSN.
1. INTRODUCTION
Wireless Sensor Network (WSN) is an emerging area having wide applicability and deployment. It is nothing
but a collection of small nodes called sensor, which can be used for collecting either physical or environmental data
from the area of interest .The data can be temperature, motion, speed, pressure, etc .Each sensor node in the network
having different parts .First part for sensing the data ,is radio transceiver ;Micro controller for processing the collected
information ,electronic circuit for interface and a battery for providing power .Each and every node in the network will
collect the data from the area of interest and it will be send to the sink node via different neighbor nodes and gateway
node .So energy of the node in the network having vital role in communication and processing of data and it in turn will
affect the lifetime of the entire network. The characteristics of WSN are,
Power consumption constrains.
Scalability.
Ease of use.
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Mobility of nodes
Less cost
To increase the energy efficiency, better routing protocols are needed. Even though, the sensors are limited by
battery, the sensor network having wide range of applicabity and deployment. In this paper, different protocols which use
the concept of clustering are studied and a comparison is made between them
2. WSN – AFFECTING FACTORS
In wireless sensor network, sensor nodes consume energy when it collects or senses the data, process the data,
transmit the data and receive the data. Data reception and transmission requires more power than collection, since it
passes the data from one node to the destination node via different intermediate nodes or through multiple paths .As the
data propagates through multiple paths needs more energy of each node and will affect the network lifetime .The wastage
of energy through communication as mentioned in [1][2] which is noted below.
• Idle Listening to the channel:
A sensor node is always listening to the idle channel to get the data destined for it.ie, the node doesn’t know
when the packet will come for it ,so the node will listen continuously to not to miss the packet, and it cause
significant amount of energy wastage.
• Collision of data:
The data collision are the main source of energy wastage ,because the collision will cause loss of packet and in
turn it requires the retransmission of that packet and reducing the power of the node .The collision occurs when
two or more nodes transmits or receives one or more packets at the same time or through the same path.
• Overhearing of data:
A node listens to the channel eventually even if it doesn’t have any data to transmit .That is node listens to the
packet that is not destined for it. It may cause reception of unwanted signals and energy wastage.
• Control data overhead:
Through the radio channel not only the data packets but also the control packets are transmitted between nodes
.The control packets provides control information for the communication in the network .A good energy
efficient routing for the WSN needs minimized amount of control packets along with the data packets so as to
reduce energy dissipation.
• Overmitting of data:
A packet will be lost, if the receiver is not at all ready to receive the message from the source but the source
have been already send .So it requires retransmission of the packet and energy will be wasted.
• Interference:
Interferences occurred during the transmission will cause energy wastage than without interference.
3. ENERGY EFFICIENT ROUTING TECHNIQUES USED IN WSN
The energy efficient routing protocols are aimed to reduce the energy dissipation and wastage of power so as to
improve the life of entire network. In Wireless Sensor Networks the routing protocols are selected in accordance with the
path which results in the prolonged life of the network and it also depends on the application in which it is deployed. The
different categories of the EER given in [1] are,
• Protocols relaying on Data
• Data centric
• Hierarchical or clustering based
• Geographical or Location based
• Mobility based
• Heterogeneous
4.CLUSTERING OR HIERARCHICAL BASED PROTOCOLS
This [3][4] category of EER guarantees significant amount of energy saving while communication. Clustering
or hierarchical protocols arranges the nodes to clusters and also improves the performance of the network.

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Fig.1: Clustering
The Sensor network is deployed in the area of interest and the area is clustered; that is each and every node in
the network becomes a member of any of the cluster but not more than one. One node from the each cluster taken as
leader node or the cluster head and this cluster head (CH) is responsible for the communication. Every other node in the
cluster will send the data to the CH rather than send to the base station (BS) directly .CH will collect and aggregate the
packets and transmit to the BS, thereby reducing the number of traffic to the base station and also reduces the energy
dissipation and so increasing the lifetime of the entire network.
The different types of hierarchical protocols are LEACH, e-LEACH, PEGASIS ,TEEN , APTEEN ,etc. In this
paper, some of these protocols are discussed below.
4.1 LEACH
LEACH [3][4][5] is a hierarchical protocol , means Low-Energy Adaptive Clustering Hierarchy. This protocol
is proposed by Dr.Wendi Rabnir Heinzelman. This protocol is mainly made by using the concept of clustering, i.e. It
selects the cluster head randomly and this CH will collect the data from the other nodes in the cluster and combines or
aggregates the data to reduce the size of the data packets and transmit it to other nodes. In the paper [5],it describes the
working of LEACH .The steps are,
1. Select initial network
2. Selection the cluster heads.
3. According to the CH divide network into clusters.
4. Compute the energy consumption of every node in the network.
5. Check whether the lifetime is closed or not.
6. If closed go to step 2.
7. Else give the output.
Fig.2: LEACH

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LEACH breaks downs the entire network into clusters and it will select the cluster head based on the energy.
That is high energy node will be selected as CH, it will change round to round. Every node will get a chance become the
CH, so that it will reduces the energy dissipation of individual nodes. It uses TDMA scheduling within the cluster and
Code Division Multiple Access is used for communicating between the clusters. LEACH performs local aggregation of
information or data from the sensor nodes in the network .It reduces the energy consumption by factor 7.Eventhough it
having some advantages it still suffers because of some drawbacks.
• LEACH protocol is inefficient to cover large area.
• It selects the CH randomly, no assurance for efficient energy management.
• Cluster heads are distributed non-uniformly; it can be at the edge.
4.2 Energy-LEACH
Its [5] an enhancement to the LEACH protocol by considering another important metric called residual energy.
In accordance with the residual energy it will decide whether a sensor node have to become a cluster head or not. This
protocol has more than one round. The working of Energy Leach is described in [5], is given here,
1. Start first round.
2. Select the nodes with more residual energy.
3. Compute residual energy of each node.
4. Check whether the energy computed is more than the scheduled energy.
5. If yes,
5.1. Select it as cluster head.
5.2. Broadcast the CH information to other nodes
6. If no,
6.1 Consider it as a common node
6.2 Send joining information to cluster head.
Fig.3: e-Leach
4.3 PEGASIS
PEGASIS [6] stands for Power Efficient Gathering in Sensor Information System is an improvement of LEACH
protocol and it is based on near optimal chain based technique .In this protocol each sensor node transmits or receive the
packet only to or from to the closest neighbor node only, that is only one node will communicate with the base station
once, means chances of collision is less and thereby we can improve the performance of the network by reducing energy
consumption. By sending data to the nearest node the nodes may form a chain starts from any selected node to the base
station i.e.; the communication overhead and energy load are distributed equally to each and every node in the network
.Through the chain the gathered or collected data from a node to the sink node is transmitted and average energy

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dissipation is minimized .This model is similar to the travelling sales man problem .It gains 100 to 300 percentage
improvement when compared with LEACH.
It works by using the concept token passing. The nodes which transmit the data to BS, that is the node which is
closer to BS will be the leader node, this node will be at random position in each round. The leader node will start the
communication by passing the token to the sending node. So the main problem in PEGASIS is the chances for single
point failure.
4.4 TEEN
TEEN [7][3][1] means Threshold Sensitive Energy Efficient Network is a protocol which is well suited for
reactive networks . It’s a combination of both hierarchical and data centric approaches .It arranges the sensor nodes into
multiple levels of hierarchy .That is it create cluster by grouping the nearest nodes in the primary level and same process
will repeats in each round until the sink node reaches .The energy consumption is reduced in TEEN by minimizing the
number of transmissions in the network. After the formation of cluster the CH is broadcasts by involvement of two
parameters known as Hard and Soft thresholds.
Hard Threshold: It is the sensed attribute’s threshold value. The node which senses this absolute value has to
switch on the transmitter and should report to CH.
Soft Threshold: A node has to switch on the transmitter and to transmit the data if any changes occurred to this
value.
TEEN is more good to save significant amount of energy but it cannot be used in the situations which require
periodic updates of sensed data. The implementation of this protocol is difficult as it requires multi level hierarchy,
attribute based naming etc.
4.5 HEED
HEED [3] is Hybrid Energy Efficient Distributed Clustering is a multi-hop clustering technique used to
minimize the energy consumption. The main aim of this protocol is to distribute the energy load to every node in the
network, minimizing the usage of energy during the CH selection and to decrease the overall control overhead over the
network. The cluster head selection in HEED is depending on two other parameters; Initial set of cluster head are
selected on the basis of the parameter residual energy and Intra cluster communication cost is the second parameter.
Lower the cost the more chance for communication between a node and its cluster head. Average Minimum Reachability
Power (AMRP) is used to find the cost; it is measured by taking the average value of minimum power level of each node
in the cluster.
5. COMPARISON
Table.1: Comparison
5. CONCLUSION
Wireless sensor networks are an emerging area and having many applications in different areas. But main issue
regarding WSN is minimized energy and lifetime. There are many studies undergoing in the network about the efficient
management of energy. In this paper different techniques were discussed to minimizing the energy dissipation and to
improve the lifetime of the network. And a comparative study between the different techniques is made to evaluate their
performance.
Protocols Main Concept Lifetime Energy
Efficient?
Drawback
LEACH Clustering Good Yes Random selection of
CH
Energy LEACH CH selection according
to residual energy
More than
LEACH
Yes Clustering overhead
PEGASIS Near optimal chain
based clustering
100-300 %
than LEACH
Yes Single point failure
TEEN Hierarchical method +
data centric
Good Yes Implementation
overhead
HEED Multi-hoping Good Yes Control and deploying
overhead

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