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

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

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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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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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

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

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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

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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

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

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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

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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

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]).

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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.


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


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.


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.


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.

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.

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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


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


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.


• 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


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]).


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


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


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.


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.

CHAPTER 3

SEMINAR PRESENTATION

Figure 3.1: An Energy Efficient Routing Protocol in WSNs

17

CHAPTER 3. SEMINAR PRESENTATION 18

Figure 3.2: Presentation Outline

Figure 3.3: Architecture of WSN


Figure 3.4: Leach Protocol

Figure 3.5: Overwiev of LEACH protocol


Figure 3.6: Data Transmission

Figure 3.7: Improved-Leach


Figure 3.8: Basic I-Leach Protocol

Figure 3.9: Work Done by I-Leach


Figure 3.10: Comparison Table

Figure 3.11: Conclusion

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