Seminar Report on I-LEACH: An Energy Efficient Routing Protocol in Wireless Sensor Networks

1. M.Tech. Synopsis Seminar
AN ENERGY EFFICIENT ROUTING PROTOCOL
IN WIRELESS SENSOR NETWORKS
Submitted in partial fulfillment of the requirements for the degree of
Master of Technology in Computer Science & Engineering
by
Divya Prabha (1322757)
Under the Supervision of
Mr. Vishal Kumar Arora
PUNJAB TECHNICAL UNIVERSITY
Jalandhar-Kapurthala Highway, Jalandhar
SHAHEED BHAGAT SINGH
STATE TECHNICAL CAMPUS
Moga Road (NH-95), Ferozepur-152004 (PB) INDIA
December 2014

2. CERTIFICATE
I, Divya Prabha (1322757), hereby declare that the work being presented in this report
on AN ENERGY EFFICIENT ROUTING PROTOCOL IN WIRELESS SENSOR NET-
WORKS is an authentic record of my own work carried out by me during my course under
the supervision of Mr. Vishal Kumar Arora. This is submitted to the Department of CSE
at Shaheed Bhagat Singh State Technical Campus, Ferozepur (affiliated to Punjab Technical
University, Jalandhar) as partial fulfillment of requirements for award of the degree of Master
of Technology in Computer Science & Engineering.
Divya Prabha (1322757)
To the best of my knowledge, this report has not been submitted to Punjab Technical Uni-
versity, Jalandhar or to any other university or institute for award of any other degree or
diploma. It is further understood that by this certificate, the undersigned do/does not
endorse or approve any statement made, opinion expressed or conclusion drawn therein,
however, approve the report only for the purpose for which it is submitted.
Mr. Vishal Kumar Arora [Supervisor]
The M.Tech. Synopsis Seminar of Divya Prabha (1322757) is held at Department of CSE,
SBS State Technical Campus, Ferozepur on ................................................
Supervisor’s Signature Mrs. Daljeet Kaur
Name: ....................................... M.Tech. Coordinator, CSE
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3. ACKNOWLEDGEMENTS
Apart from the efforts of myself, the success of Masters dissertation depends largely on
the encouragement and guidelines of many others. I take this opportunity to express my
gratitude to the people who have been instrumental in the successful completion of this
project. I would like to express the deepest appreciation to my supervisor, Mr. Vishal
Kumar Arora, Assistant Professor, Department of Computer Science & Engineering , SBS
State Technical Campus, Ferozepur (Punjab), India, who has the attitude and the substance
of a genius: he continually and convincingly conveyed a spirit of adventure in regard to
research and scholarship, and an excitement in regard to teaching. Without his guidance
and persistent help this dissertation would not have been possible. I cant say thank you
enough for his tremendous support and help. I feel motivated and encouraged every time I
attend his meeting. Without his encouragement and guidance this project would not have
materialized.
I am becoming increasingly present to the fact that research can indeed be an enjoyable and
rewarding experience, despite the tedium and hardwork involved. This report is truly the
culmination of his support, motivation, generous help and teachings. I can never forget the
cheerful moments of my life when this charismatic personality accepted me as a research
scholar. I must record my sincere gratitude to him for not only the great store-houses of
knowledge he bestowed upon me but also for the chiseling and grooming. I received in large
measure in spheres of academic, professional and personal life. Without his constant chase
and help, this work could not have taken this shape. I am pretty sure that his guidance
would go a step beyond this thesis report and would be reflected in Doctorate Course and a
couple of more publications of improved quality and of greater rigor and coverage, which I
now look forward to.
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4. iii
Mr. Vishal Kumar Arora’s mature research advice in the very initial stage never let me down
in research throughout the longish period of research. I could learn the technique of orga-
nizing and writing quality research matter only because of his erudite teachings throughout
the project. This in fact has left a permanent impression on my personality and written and
verbal communication. I also express my great admiration and indebtedness for the man-
ner in which he painstakingly carried out a thorough editing of our papers and the seminar
report, despite his overwhelming busy schedule and numerous responsibilities.
There are several other persons who made important contributions during this period. The
guidance and support received from all the members who contributed and who are contribut-
ing to this project, was vital for the success of the project. I am grateful for their constant
support and help.
My sincere thanks to Dr. T. S. Sidhu, Principal, SBS State Technical Campus, Ferozepur
(Punjab) and to Mr. Japinder Singh, Head, CSE Department, SBS State Technical
Campus, Ferozepur (Punjab).
I wish to acknowledge the magnificent support I have received from my fellow friends Ms.
Shubhi Bansal, Ms. Reenkamal Gill and Ms. Priya Chawla in the form of useful
discussions throughout this work.
My sincere thanks to my friend Ms. Jaspreet Kaur for clearing my doubts in LaTeX and
making my writing part easier.
Finally, I must thank GOD and my parents Mr. Anil Kumar and Mrs. Pushpa for
giving me the environment to study, people to help, opportunities to encash and potential
to succeed.
Place: SBS STC Ferozepur
Date: December 8, 2014 Divya Prabha

5. ABSTRACT
Wireless sensor network is defined as wireless network of sensor nodes in which Routing
technique is one of the most challenging issues. One of the major issues in WSNs is the
limited battery power of the network sensor nodes. The battery power plays an important
role in increasing the lifetime of the nodes. In WSN, routing among various routing technique,
energy consumption is one of the most important consideration.
To minimize energy consumption hierarchical routing protocols are the best known protocols.
LEACH protocol is one of the most energy efficient clustering protocols. Leach increases
the network lifetime by consuming a small percentage of the total dissipated energy in the
network. We have surveyed the different hierarchical routing protocols, developed from the
LEACH. The LEACH protocol and its various descendant protocols like E-LEACH, TL-
LEACH, MLEACH, V-LEACH, LEACH-A, LEACH-B, LEACH-S are described in details
in the context of this Thesis synopsis.
In this seminar report, the main focus is on I-LEACH i.e an improved energy efficient routing
protocol is which saves a significant portion of inner-network communications energy. To do
this, the proposed routing protocol selects sensor nodes with higher residual energy, more
neighbors, and lower distance from the Base Station (BS) as Cluster Head (CH) nodes. Then,
it manages sensor nodes appropriately and constructs clusters such a way to maximize WSN
lifetime and minimize average energy dissipation per each sensor node.
Place: Ferozepur Divya Prabha (1322757)
Date: December 8, 2014
iv

6. ABBREVIATIONS
Abbreviations Description
ADV Advertisement
BS Base Station
CDMA Code Division Multiple Access
CH Cluster Head
C-Leach Centralized Low-energy Adaptive Clustering Hierarchy
CM Cluster Member
CSMA Carrier Sense Multiple Access
GPS Global Positioning System
I-Leach Improved Low-energy Adaptive Clustering Hierarchy
LEACH Low-energy Adaptive Clustering Hierarchy
Leach-A Advanced Low Energy Adaptive Clustering Hierarchy
Leach-B Balanced Low Energy Adaptive Clustering Hierarchy
Leach-F Fixed no. of clusters Low Energy Adaptive Clustering Hierarchy
Leach-L Energy Balanced Low Energy Adaptive Clustering Hierarchy
Leach-S Solar aware Low energy adaptive clustering hierarchy
MAC Media Access Control
M-Leach Multi-level Low-energy Adaptive Clustering Hierarchy
QoS Quality of Service
v

7. vi
Abbreviations Description
REQ Request
TDM Time Division Multiplexing
TDMA Time Division Multiple Access
TTL Time To Live
TL-Leach Two-level Low-energy Adaptive Clustering Hierarchy
V-Leach Vice Cluster-Head Low-energy Adaptive Clustering Hierarchy
WSNs Wireless Sensor Networks

8. LIST OF FIGURES
1.1 Wireless Sensor Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 Classification of routing in WSNs . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 Clustering in LEACH Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2 Flow chart of the Set-up phase of the LEACH protocol . . . . . . . . . . . . . 9
2.3 Flow chart of the Steady phase of the LEACH protocol . . . . . . . . . . . . 10
3.1 An Energy Efficient Routing Protocol in WSNs . . . . . . . . . . . . . . . . . 17
3.2 Presentation Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.3 Architecture of WSN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.4 Leach Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.5 Overwiev of LEACH protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.6 Data Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.7 Improved-Leach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.8 Basic I-Leach Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.9 Work Done by I-Leach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.10 Comparison Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.11 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
vii

9. CONTENTS
CERTIFICATE i
ACKNOWLEDGEMENTS ii
ABSTRACT iv
ABBREVIATIONS v
LIST OF FIGURES vii
CONTENTS viii
1 INTRODUCTION 1
1.1 Wireless sensor network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.1 Energy-efficient Routing Algorithms . . . . . . . . . . . . . . . . . . . 3
1.1.1.1 Data centric . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.1.2 Hierarchical . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.1.3 Data centric . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1.2 I-LEACH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.4 Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 LITERATURE SURVEY 7
2.1 LEACH ALGORITHM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3 ASSUMPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.4 ALGORITHM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.5 VARIATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.5.1 LEACH-E (Energy Low Energy Adaptive Clustering Hierarchy) . . . 12
2.5.2 LEACH-C (Centralized Low Energy Adaptive Clustering Hierarchy) . 12
2.5.3 TL-LEACH (Two-Level Low Energy Adaptive Clustering Hierarchy) . 12
2.5.4 MULTIHOP LEACH . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
viii

10. ix
2.5.5 LEACH-F(Fixed no.of clusters Low Energy Adaptive Clustering Hier-
archy) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.5.6 LEACH-ME (Mobile-Enhanced Low Energy Adaptive Clustering Hi-
erarchy) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.5.7 LEACH-B (Balanced Low Energy Adaptive Clustering Hierarchy) . . 13
2.5.8 LEACH-M (Mobile Low Energy Adaptive Clustering Hierarchy) . . . 14
2.5.9 LEACH-H (Hybrid Low Energy Adaptive Clustering Hierarchy) . . . 14
2.6 IMPROVED LEACH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.7 IMPROVED LEACH Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.8 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3 SEMINAR PRESENTATION 17
REFERENCES 24

11. CHAPTER 1
INTRODUCTION
In this chapter, we first provide an overview of Wireless Sensor Networks, then we focus on
the Energy-efficient Routing Algorithms. In addition, we describe an Improved-Leach routing
protocol in Wireless Sensor networks.
1.1 Wireless sensor network
Wireless sensor network (WSN) is a collection of large number of sensor nodes which senses
the environment and send data to sink. WSNs also refers to a group of spatially dispersed and
dedicated sensors for monitoring and recording the physical conditions of the environment
and organizing the collected data at a central location. WSN is used in various fields like
military, environment, health, home and other commercial areas. A sensor network design
is influenced by many factors like fault tolerance, scalability, production costs, operating en-
vironment, transmission media and power consumption (Bandyopadhyay and Coyle [2003]).
Therefore, it is highly difficult to study energy saving schemes for sensing of dynamic event.
For example, a forest monitoring application involves static monitoring approach whereas a
target tracking application involves a dynamic monitoring approach.
When a WSN is activated, various tasks are performed to establish the necessary infrastruc-
ture to the network, such as distribution of sensor nodes and routing of data transmission,
which will allow the sensor node to perform the applications normally. In particular, each
node must discover which other nodes it can directly communicate with, and its radio power
must ensure the connectivity (Heinzelman et al. [2002]).
1

12. CHAPTER 1. INTRODUCTION 2
WSNs are usually deployed in an environment to monitor static or dynamic events. The
measurement of static events (such as temperature, humidity etc) is very easy to carry out.
On the other hand, dynamic events are typically non-cooperative event is the movement of
an unwanted vehicle in a battle field and the movement of whales in the ocean. They are
not easy to monitor and they are not stable as they go up and down.
Sensor network requires certain protocol for efficient performance. For instance, protocol can
come in form of a specific application with a defined order to aggregate data and optimizing
energy consumption. This kind of protocol is referred to as hierarchical routing. Moreover,
we have also a data centric routing protocol which describes a network environment whereby
a sensor node also relies on data centric approach which performs sensing application to
locate route path from multiple sources to a single destination. With this in mind, data from
every node in a network can be describe by a list of attribute value pairs called attribute-
based addresses, such that a node can expose its availability to the entire sensor network.
It is however essential to improve the energy efficiency for wireless sensor networks as the
energy designated for sensor nodes is usually extremely limited. And, due to the fact that
there is an increase in societal reliance on wireless sensor network technology, we can foresee
the complexity of individual networks as well as huge increment in number of networks.
Figure 1.1: Wireless Sensor Network
Due to the nature of the WSN, sensor nodes are normally powered by the use of batteries and
thereby having a very constrained budget in terms of energy [1]. To effectively maintain the
network sensors to have longer lifetimes, all areas of the network should be carefully designed
to be energy efficient. Among many methods, clustering the sensor nodes into groups, so
that sensors send information to only the cluster heads (CH) and then the CH communicate
the aggregated information to the base stations, may be a good method to minimize energy
consumption in WSN. It is necessary to organized sensors in cluster form to reduce energy
consumed when transmitting information from nodes to the base station.

13. CHAPTER 1. INTRODUCTION 3
1.1.1 Energy-efficient Routing Algorithms
Energy efficient routing algorithm can be categorized as follows: data centric routing algo-
rithm, location based routing algorithm and hierarchical routing algorithm . Data centric
routing algorithm uses meta data to find the route from source to destination before any
actual data transmission to eliminate redundant data transmission Location based routing
algorithm requires actual location information for every sensor node. Hierarchical routing
algorithm divides the network into clusters. Cluster head (CH) is elected in each cluster.
CH collects data from its members, aggregates the data and sends to sink. This approach is
energy efficient but relatively complex than other approaches (Akkaya and Younis [2005]).
Figure 1.2: Classification of routing in WSNs
1.1.1.1 Data centric
Data centric protocols are query based and they depend on the naming of the desired data,
thus it eliminates much redundant transmissions. The BS sends queries to a certain area
for information and waits for reply from the nodes of that particular region. Since data is
requested through queries, attribute based naming is required to specify the properties of
the data. Depending on the query, sensors collect a particular data from the area of interest
and this particular information is only required to transmit to the BS and thus reducing the
number of transmissions. e.g. SPIN was the first data centric protocol.
1.1.1.2 Hierarchical
Hierarchical routing is used to perform energy efficient routing, i.e., higher energy nodes
can be used to process and send the information; low energy nodes are used to perform the

14. CHAPTER 1. INTRODUCTION 4
sensing in the area of interest. e.g. LEACH, TEEN, APTEEN.
1.1.1.3 Data centric
Location based routing protocols need some location information of the sensor nodes. Lo-
cation information can be obtained from GPS (Global Positioning System) signals, received
radio signal strength, etc. Using location information, an optimal path can be formed without
using ooding techniques. e.g. Geographic and Energy-Aware Routing(GEAR)
1.1.2 I-LEACH
In order to efficiently use the power, a new version of the self-organized routing algorithm
based on LEACH (Low energy adaptive clustering hierarchy), named as I-LEACH (Improved
Low energy adaptive clustering hierarchy), that owns advantages of tree routing and hier-
archical routing. Improved-Leach selects CH nodes based on sensor nodes factors higher
residual energy, more neighbors, and lower distance from the Base Station (BS) as Cluster
Head (CH) nodes. Improved-Leach also manages the sensor nodes and clusters to reduce the
energy consumption within the WSN. Similarly, in the proposed algorithm, the operation of
selecting the route with minimal energy cost is effective in increasing the WSN lifetime. The
proposed algorithm has been improved the network lifetime, reduces the energy consump-
tion of the network, and improves the successfully delivered packet ratio as compared to the
previous algorithms(Jing et al. [2013]).
Similar to previous works, the proposed routing algorithm is applicable for a WSN which
has following specifications:
1. All nodes have the same initial energy and their batteries are not rechargeable. Sensor
nodes die with the end of their battery.
2. Sensor nodes are fixed i.e., when they are first randomly distributed, they remain in
the same place.
3. Each sensor node has a unique ID and knows its current position and its remaining
energy.
4. Each sensor node has enough power to communicate directly with the BS.
5. In a cluster, nodes can obtain various sensory data.
6. Every sensor node has a computational unit and a memory unit. Nodes can run some
processes, including the definition of sensed data and aggregated data, etc.

15. CHAPTER 1. INTRODUCTION 5
Similar to other cluster-based routing algorithms, three phases of CH nodes selection, cluster
formation, and data transfer should be done by the proposed routing algorithm. In the first
phase, the CH nodes must be selected among the sensor nodes of WSN. In the second phase,
according to the selected CH nodes, clusters should be formed, i.e., non-CH nodes should be
appropriately assigned to CH nodes. Finally, in the third phase, data transferring from the
sensor nodes to the CH nodes and subsequently from CH nodes to the BS must be done.
Advantages :
1. Tremendous advantage when base-station is far away from sensing area.
2. The average energy consumption of the WSN is reduced.
3. The WSN lifetime is extended as compared to LEACH.
Disadvantages :
1. Non-uniform distribution of cluster heads, thus increases the total energy dissipated in
the network.
2. Does not consider mobility of nodes and sink.
3. Does not give solution in case of CH dies before sending data to the BS.
1.2 Motivation
LEACH is distributed clustering algorithm since each node makes its decision based on the
local information. So it has better scalability. The operation of LEACH is usually separated
into two phases, the set-up phase and the steady-state phase. In set-up phase, node competes
for becoming a CH.
where r is the current round, p is the predetermined percentage of cluster heads, G is the
set of nodes that have not been cluster heads in the last 1/p. In the steady-state phase, the
member nodes begin sensing and transferring data to its cluster head. Then, data aggregation
is performed in cluster heads and communication is done in each cluster via TDMA. Thus,
a non-cluster head node can save energy by turning off the radio.
By analyzing, we know some defects of LEACH. For instance, the selection of cluster heads
does not use energy. The direct result is that the low power node can become a cluster head,
it will deplete its energy quickly. The member nodes choose a cluster head to join in only
by distance between themselves and a cluster head. It may result in the formation of the
minimum cluster or the maximum cluster. That is energy balance against among all nodes
of the network.

16. CHAPTER 1. INTRODUCTION 6
1.3 Objectives
The primary objectives of this research work are summarized as follows:
1. To design an Energy-efficient communication protocol for wireless sensor networks.
2. To maximize the lifetime of the network.
3. To increases the life-time of the sensor nodes.
4. Scalable (in terms of network diameter) communication protocol.
5. Use uniform, battery-operated nodes.
1.4 Methodology
The methodology followed in this thesis is:
1. One of the foremost requirement to make this new variant of Energy Efficient Algorithm
(Leach) is to deep study and understand its variants.
2. Second difficult requirement is to design programs of all these evolutionary algorithms
and to implement it on simulator and get the output.
3. Study and compare the results of Leach protocol and its variants by means of analyzing
graphs
4. Propose a new algoritm in existing routing protocol to improve energy efficiency and
network lifetime of wireless sensor networks.
5. Validate the new proposed technique with existing techniquess.

17. CHAPTER 2
LITERATURE SURVEY
The needed detailed literature survey, to get preliminary knowledge and search scope of inves-
tigation, to implement Low energy adaptive clustering hierarchy, is explained in this chap-
ter.This Report presents investigational studies in several energy efficient routing algorithms
and its general purpose. This Chapter contains the overview of Leach and its variants and
the simulator on which we test and implement these algorithms.
2.1 LEACH ALGORITHM
W.Heinzelman, introduced a hierarchical clustering algorithm for sensor networks,called Low
Energy Adaptive Clustering Hierarchy (LEACH). LEACH arranges the nodes in the network
into small clusters and chooses one of them as the cluster-head. Node first senses its target
and then sends the relevant information to its cluster-head. Then the cluster head aggregates
and compresses the information received from all the nodes and sends it to the base station.
The nodes chosen as the cluster head drain out more energy as compared to the other nodes
as it is required to send data to the base station which may be far located. Hence LEACH
uses random rotation of the nodes required to be the cluster-heads to evenly distribute energy
consumption in the network. After a number of simulations by the author, it was found that
only 5 percent of the total number of nodes needs to act as the cluster-heads. TDMA/CDMA
MAC is used to reduce inter-cluster and intra-cluster collisions. This protocol is used were
a constant monitoring by the sensor nodes are required as data collection is centralized (at
the base station) and is performed periodically.
7

18. CHAPTER 2. LITERATURE SURVEY 8
Figure 2.1: Clustering in LEACH Protocol
2.2 OPERATION
LEACH operations can be divided into two phases:-
1. Setup phase
2. Steady phase
In the setup phase, the clusters are formed and a cluster-head is chosen for each cluster.
While in the steady phase, data is sensed and sent to the central base station. The steady
phase is longer than the setup phase. This is done in order to minimize the overhead cost.
1. Setup phase :- During the setup phase, a predetermined fraction of nodes, p, choose
themselves as cluster-heads. This is done according to a threshold value, T(n). The
threshold value depends upon the desired percentage to become a cluster-head- p, the
current round r, and the set of nodes that have not become the cluster-head in the last
1/p rounds, which is denoted by G. The formulae is as follows :
T(n) = p/1-p[r mod(1/p)] if n E G
T(n) = 0 otherwise
Every node wanting to be the cluster-head chooses a value, between 0 and 1. If this
random number is less than the threshold value, T(n), then the node becomes the
cluster-head for the current round. Then each elected CH broadcasts an advertisement
message to the rest of the nodes in the network to invite them to join their clusters.
Based upon the strength of the advertisement signal, the non-cluster head nodes decide

19. CHAPTER 2. LITERATURE SURVEY 9
to join the clusters. The non-cluster head nodes then informs their respective cluster-
heads that they will be under their cluster by sending an acknowledgement message.
After receiving the acknowledgement message, depending upon the number of nodes
under their cluster and the type of information required by the system (in which the
WSN is setup), the cluster-heads creates a TDMA schedule and assigns each node a
time slot in which it can transmit the sensed data. The TDMA schedule is broadcasted
to all the cluster-members. If the size of any cluster becomes too large, the cluster-
head may choose another cluster- head for its cluster. The cluster-head chosen for the
current round cannot again become the cluster-head until all the other nodes in the
network haven’t become the cluster-head.
Figure 2.2: Flow chart of the Set-up phase of the LEACH protocol
2. Steady phase :- During the steady phase, the sensor nodes i.e. the non-cluster head
nodes starts sensing data and sends it to their cluster-head according to the TDMA
schedule. The cluster-head node, after receiving data from all the member nodes,
aggregates it and then sends it to the base-station.
After a certain time, which is determined a priori, the network again goes back into
the setup phase and new cluster-heads are chosen. Each cluster communicates using

20. CHAPTER 2. LITERATURE SURVEY 10
different CDMA codes in order to reduce interference from nodes belonging to other
clusters.
Figure 2.3: Flow chart of the Steady phase of the LEACH protocol
2.3 ASSUMPTIONS
LEACH protocol takes into a number of assumptions which may create a lot of problems in
the real-time systems. A few of these assumptions are as follows:
• All nodes can transmit with enough power to reach the base station if needed.
• Each node has computational power to support different MAC protocols.
• Nodes always have data to send.
• Nodes located close to each other have correlated data.

21. CHAPTER 2. LITERATURE SURVEY 11
• All nodes begin with the same amount of energy capacity in each election round,
assuming that being a CH consumes approximately the same amount of energy for
each node.
2.4 ALGORITHM
The algorithm for the Low Energy Adaptive Clustering Hierarchy (LEACH) implemented is:
Setup phase :
1. CN=> r
2. If r > T(n) then, CH = CN else, goto step1
3. CH => G : id(CH) , join adv
4. A(i) -> CH(j) : id(A(i)) , id(CH(j)) , join req
5. CH(j)-> A(i) : id(CH(j)) , < t(i) , id(A(i)) >
Steady phase :
1. A(i) -> CH(j) : id(A(i)) , id(CH(j)) , info
2. CH -> BS : id(CH) , id(BS) , aggr info
The various symbols used here are :
CN : candidate node to become the cluster head.
r : randomvariable(0 > r > 1)
T(n) : threshold value
CH : cluster head
G : all nodes in the network
id : identification number
join adv : advertisement to join the cluster
A : normal node
Join adv : request to join the cluster
t : time-slot to send the sensed data
=> : broadcast
->: unicast

22. CHAPTER 2. LITERATURE SURVEY 12
2.5 VARIATIONS
2.5.1 LEACH-E (Energy Low Energy Adaptive Clustering Hierarchy)
LEACH-E is the enhancement of LEACH. It involves a cluster head selection algorithm which
have non-uniform starting energy level among the sensors having global information about
the other sensors. In order to minimize the total energy consumption .the required number
of cluster heads has to scale as the square root of the total number of sensor nodes and this
can be determined by Leach-E (Chaurasiya et al. [2011]).
2.5.2 LEACH-C (Centralized Low Energy Adaptive Clustering Hierarchy)
It involves a centralized clustering algorithm. The steady state will remains the same whereas
the setup phase contains each node sending information about the current location and also
the energy level to the base station .The base station thus by utilizing the global information
of the network produce better clusters that requires the less energy for data transmission..It
needs GPS or the other location tracking method. The base station then broadcasts the
information to all nodes in the network (Muruganathan et al. [2005]).
2.5.3 TL-LEACH (Two-Level Low Energy Adaptive Clustering Hierarchy)
Two-Level Hierarchy LEACH (TL-LEACH) is extension to the LEACH algorithm. It has
two levels of cluster heads (primary and secondary) instead of a single one. Here, the pri-
mary cluster head in each cluster communicates with the secondaries, and the corresponding
secondaries in turn communicate with the nodes in their sub-cluster. Data fusion can also
be performed here as in LEACH. In addition to it, communication within a cluster is still
scheduled using TDMA time-slots. The organization of a round will consist of first select-
ing the primary and secondary cluster heads using the same mechanism as LEACH, with
the a priori probability of being elevated to a primary cluster head less than that of a sec-
ondary node (Jindal and Gupta [2013]). Communication of data from source node to sink is
achieved in two steps: Secondary nodes collect data from nodes in their respective clusters.
Data fusion can be performed at this level. Primary nodes collect data from their respective
secondary clusters. Data-fusion can also be implemented at the primary cluster head level.
The two-level structure of TLLEACH reduces the amount of nodes that need to transmit to
the base station, effectively reducing the total energy usage (Loscri et al. [2005]).

23. CHAPTER 2. LITERATURE SURVEY 13
2.5.4 MULTIHOP LEACH
The distance between the cluster head and the base station is increased enormously when the
network diameter is increased beyond a certain level in which the scenario is not suitable for
Leach routing protocol. The energy efficiency of the protocol can be increased by using multi-
hop communication within the cluster. Multihop-Leach is a complete distributed clustering
based routing protocol. The multihop approach is utilized inside the cluster and outside the
cluster (Xiangning and Yulin [2007]).
2.5.5 LEACH-F(Fixed no.of clusters Low Energy Adaptive Clustering Hi-
erarchy)
In Leach-F ,once the clusters are formed they are fixed and there is no setup overhead at the
beginning of each round.It uses the same centralized cluster formation algorithm as Leach-
C for deciding the clusters.In Leach-F, new nodes cannot be added to the system and do
not adjust their behaviour based on nodes dying.Furthermore,the node mobility cannot be
handled by the Leach-F. Only the cluster head position is rotated among the nodes within the
cluster. Leach-F may or may not be provided energy saving. A stable cluster and rotating
cluster head concept is used by Leach-F in which cluster once formed is maintained stable
throughout the network lifetime in order to avoid re-clustering.
2.5.6 LEACH-ME (Mobile-Enhanced Low Energy Adaptive Clustering
Hierarchy)
LEACH-ME considers all the sensor nodes are mobile (including CHs) which was not been
considered in previous LEACH versions. The CH selection procedure encapsulates mobility
factor and residual energy constraints. A node with the minimal mobility factor is selected
as a CH, if the residual energy of the node is not below a threshold value. It also provides
two TS facility(like LECH-M) for non-CH node further providing an extra ACTIVE time
slot during TDMA scheduling where all member nodes wake up simultaneously, broadcast
their IDs with timestamp information and receive their neighboring nodes IDs by setting a
time out. However in LEACH-ME ACTIVE slot are entirely for mobility factor calculation
hence not energy efficient (Kumar et al. [2008]).
2.5.7 LEACH-B (Balanced Low Energy Adaptive Clustering Hierarchy)
Leach-B uses the decentralized algorithms of cluster formation where each sensor node only
knows about its own position and the final receiver and does not know about the position

24. CHAPTER 2. LITERATURE SURVEY 14
of all the sensor nodes. Leach-B involves the following techniques. Cluster head selection
algorithm, Cluster formation and data transmission with multiple access. By evaluating the
energy dissipated in the path between final receiver and itself, each of the sensor node chooses
its cluster head. Efficiency of Leach-B is better than Leach (Pantazis et al. [2013]).
2.5.8 LEACH-M (Mobile Low Energy Adaptive Clustering Hierarchy)
In LEACH-Mobile (LEACH-M) routing protocol cluster formation and CH selection mecha-
nism is same as LEACH. It clearly copes with the drawbacks of earlier protocol i.e. support
for mobile sensor nodes further it treats data as vital information. Thus it allocates two
timeslots (TS) for all non-CH nodes and the facility of JOIN-ACK message when they are
in the vicinity of other cluster. If a non-CH node A, does not receive any data request
from CH at its allocated TS then A goes to sleeping mode(saving battery life) and waits
for next frame. Again if A does not gets data request then it sends JOIN-ACK message
to new cluster. However, LEACH-M handles node mobility by assuming that the CHs are
stationary. Hence, LEACH-M is not considered efficient in terms of energy consumptions
and data delivery rate because a large number of packets are lost if the CH keeps moving
before selecting a new CH for the next round (Deng et al. [2011]).
2.5.9 LEACH-H (Hybrid Low Energy Adaptive Clustering Hierarchy)
LEACH-H combines the advantages of LEACH and LEACH-C. It resolves the drawback of
LEACH (uncertainty in Number of CHs) by selecting CH at first round by BS itself moreover
in further round it selection of a cluster head for Cluster is done by a the Current CH which
eradicates the issue of dependence on BS in LEACH-C. LEACH-H increases the survival time
of network and extent of load balancing. LEACH-H composed of Initialization of Cluster
and Reconstruction of Cluster, simulated annealing algorithm is used to select the optimized
CH in first round i.e. Cluster initialization phase and in Reconstruction phase Cluster head
is selected by Current CH. However LEACH-H does not say anything about whether there
will be separate TS for cluster head selection in TDMA scheduling (Wang et al. [2009]).
2.6 IMPROVED LEACH
I-LEACH protocol is defined as an improvement over the LEACH protocol. The only differ-
ence is in the CH selection procedure. At first round, a CH is to be chosen, all the nodes
have same probability to be CH. After first round, nodes energy is also considered in CH
selection(Beiranvand et al. [2013]). In this Literature Review, an energy proposed algorithm

25. CHAPTER 2. LITERATURE SURVEY 15
saves a significant portion of inner network communications energy.To do this, the proposed
routing algorithm selects sensor nodes by considering the following factors:-
1. higher residual energy
2. more neighbors
3. lower distance from the Base Station (BS) as Cluster Head (CH)
2.7 IMPROVED LEACH Algorithm
Step 1: Let Ni or Nj denote a common node
Step 2: S(Ni) = (N1, N2 ........Nn) denote the set of n nodes
Step 3: E(Ni) denote energy in a node
Step 4: Nxyz denote node location
Step 5: Ci denote a cluster ID
Step 6: CH(Ni) denote a cluster head node
Step 7: dij denote distance measured from node Ni to Nj
Step 8: thresh(Ni) denote the threshold value of node Ni Initialization
Step 9: Create node Ni
Step 10: Set node position Nxyz
Cluster formation
Step 11: Divide the sensor field into identical sub-region Ri
Step 12: Select CH from each sub-region Ri based on threshold value
Step 13: if Ni belongs to Ri AND thresh(Ni) < Threshold AND hasnotbeenCHyet then Step
14: Ni = CH (Ni) for sub-region Ri
Step 15: else
Step 16: Ni = Nj (normal node)
Step 17: end if
Send Data to Base station
Step 18: CH(Ni) sends data to Base station
Repeat the steps 12 to 18 for different rounds
End of algorithm
2.8 Future Work
1. Implementation of IMPROVED-LEACH protocol on Heterogeneous wireless sensor
networks.

26. CHAPTER 2. LITERATURE SURVEY 16
2. Next improvement can be possible by considering sink mobility and to ensure successful
delivery of data.
3. Design of a better routing protocol in case when CH dies before sending the data to
the BS.
4. The future work can include some more level of hierarchy and mobility in the network.

27. CHAPTER 3
SEMINAR PRESENTATION
Figure 3.1: An Energy Efficient Routing Protocol in WSNs
17

28. CHAPTER 3. SEMINAR PRESENTATION 18
Figure 3.2: Presentation Outline
Figure 3.3: Architecture of WSN

29. CHAPTER 3. SEMINAR PRESENTATION 19
Figure 3.4: Leach Protocol
Figure 3.5: Overwiev of LEACH protocol

30. CHAPTER 3. SEMINAR PRESENTATION 20
Figure 3.6: Data Transmission
Figure 3.7: Improved-Leach

31. CHAPTER 3. SEMINAR PRESENTATION 21
Figure 3.8: Basic I-Leach Protocol
Figure 3.9: Work Done by I-Leach

32. CHAPTER 3. SEMINAR PRESENTATION 22
Figure 3.10: Comparison Table
Figure 3.11: Conclusion

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