a modified energy efficient communication protocol for wireless sensor network

8/20/2019 A Modified Energy Efficient Communication Protocol for Wireless Sensor Network

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International Journal of Scientific Research Engineering & Technology (IJSRET)Volume 2 Issue 11 pp 717-723 February 2014 www.ijsret.org ISSN 2278 – 0882

IJSRET @ 2014

A Modified Energy Efficient Communication Protocol for Wireless

Sensor Network

Aman Deep SinghM. Tech (Computer Science & Engineering)

B.S.A College of Engineering and Technology Mathura (U.P) INDIA

ABSTRACTWireless distributed micro sensor systems will enable

the reliable monitoring of a variety of environments for

both civil and military applications. . Clustering sensor

nodes is an effective technique for achieving these goals.

LEACH (Low Energy Adaptive Clustering Hierarchy) is

one of popular cluster-Based structures, which has been

widely proposed in wireless Sensor networks. LEACHuses localized coordination to enable the scalability and

robustness for dynamic networks. LEACH utilizes the

randomization of local cluster based stations to evenly

distribute the load among the sensors in the network.

LEACH uses a TDMA based MAC protocol the

proposed protocol is simulated and the results show a

significant reduction in network energy consumption.

Keywords: WSN (Wireless Sensor Networks),

hierarchical clustering, LEACH Algorithm, network

lifetime.

I. INTRODUCTIONA wireless sensor network contains hundreds or

thousands of these sensor devices that have ability to

communicate either directly to the Base Station (BS) or

among each other. LEACH is one of the protocols thatgive the guarantee about the allocation of energy in the

sensor node homogeneously. A homogeneous sensor

networks can be defined as a network consisting of

identical nodes in terms of energy, processing

capabilities, and sensing range. Micro sensor network consist of many spatially distributed sensors, which are

used to monitor various kinds of ambient conditions liketemperature, humidity, etc and then transform them into

electric signal. A sensor is equipped with a radio

transceiver, a small microcontroller, and an energysource usually a battery. . The nodes in WSNs are

usually battery operated sensing devices with limited

energy resources and replacing or replenishing the

batteries is usually not an option. Usually, sensor nodes

are scattered in the sensing field.

Routing in WSNs is very challenging due to the specific

characteristics that distinguish WSNs from other

wireless networks. Network protocols must be designed

to achieve fault tolerance while minimizing energyconsumption .In addition since the limited wireless

channel bandwidth must be shared among the sensors in

the network, routing protocols should be able to performlocal collaboration to reduce channel bandwidth

requirements. Based on the network structure adopted

routing protocols for WSNs can be classified into fla

network routing location-based network routing. In fla

network routing, all nodes have the same functionality

and they work together to perform sensing and routing

tasks.

The Sensor Protocols for Information via egotiation

(SPIN) [4] and Directed Diffusion [5] fall into this

category. Hierarchical network routing divides the

network into clusters to achieve energy-efficient

scalability and one of the famous hierarchical network

routing protocol is low-energy adaptive clustering

hierarchy (LEACH) [1]. In location-based network

routing, location information of nodes is used to

compute the routing path. This information can be

obtained from global positioning system (GPS) devices

attached to each sensor node. Examples of location-

based network routing protocols include geography

adaptive routing (GAF) [1] and Geographic and Energy-

Aware Routing (GEAR) [6].

Sensor networks contain too much data for an end-user

to process. Therefore, automated methods of combining

or aggregating the data into a small set of meaningful

information is required [7, 8]. In addition to helping

avoid information overload, data aggregation, also

known as data fusion, can combine several unreliable

data measurements to, being the area where we want to

monitor some ambient Conditions. The information

collected by sensor nodes is routed to the Base Station

either directly or through other sensor nodes.

During the creation of network topology, the process of

setting up routes in WSNs is usually influenced by




IJSRET @ 2014

energy considerations. The classification performed onthe aggregated data might be performed by a human

operator or automatically. Both the method of per-

forming data aggregation and the classification algorithm

are application-specific.Sensor nodes are randomly scattered so multi-hop

routing is unquestionably defacto. Many research

projects and papers have shown that the hierarchical

network routing and specially the clustering mechanisms

make significant improvement in WSNs in reducing

energy consumption and overhead [7, 8] also have to

note that most of clustering protocols proposed for

WSNs assume that nodes are stationary. The reason for

sensor nodes to be taken as stationary is the assumption

of simple network topology. Clustering protocols can

reduces signaling overhead since they do not have to

manage the mobility pattern or location information of sensor nodes. As a result, it allows nodes saving more

energy leading to a longer network life time. However,

with some applications such as animal tracking, search

and rescue activities this assumption is not very realistic;

hence there are raising demands for clustering protocols

to support mobile nodes.

Clustering network is efficient and scalable way to

organize WSNs. A cluster head responsible for

Conveying any information gathered by the nodes in its

cluster and may aggregate and compress the data before

transmitting it to the sink. However, this added

responsibility results in a higher rate of energy drain atthe cluster heads. One of the most popular clustering

mechanisms, LEACH, addresses this by robabilistically

rotating the role of cluster head among all nodes.

However, unless each node selects its probability of

becoming a cluster head wisely, the performance of the

network may be far from optimal. The main focus of this

paper is modifying LEACH clustering algorithm. This

algorithm fully utilizes the location information of

network nodes in routing to reduce the routing cost.

By analyzing the advantages and disadvantages of

conventional routing protocols using our model of

sensor networks, we have developed LEACH (Low-

Energy Adaptiv Clustering Hierarchy), a clustering-

based protocol that minimizes energy dissipation in

sensor networks. The key features of LEACH are:

• Localized coordination and control for cluster

set-up and operation

• Randomized rotation of the cluster “base

stations” or “cluster -heads” and thecorresponding clusters.

• Local compression to reduce global

communication

The use of clusters for transmitting data to the base

station leverages the advantages of small transmidistances for most nodes, requiring only a few nodes to

transmit far distances to the base station. However

LEACH out-performs classical clustering algorithms by

using adaptive clusters and rotating cluster-heads

allowing the energy requirements of the system to be

distributed among all the sensors. In addition, LEACH is

able to perform local computation in each cluster to

reduce the amount of data that

II. RELATED WORKLEACH is a kind of cluster-based routing protocols

which uses distributed cluster formation. LEACHrandomly selects a few sensor nodes as cluster heads

(CHs) and rotates this role to evenly distribute the

energy load among the sensors in the network. The ideais to form clusters of the sensor nodes based on the

received signal strength and use local cluster heads as

routers to the sink. In LEACH, the Cluster Heads

compress data arriving from member nodes and send an

aggregated packet to the BS in order to reduce theamount of information that must be transmitted to the

BS. In order to reduce inter & intra cluster interference.

Clustering is the method by which sensor nodes in a

network organize themselves into hierarchical structuresBy doing this, sensor nodes can use the scarce networkresources such as radio resource, battery power more

efficiently. Within a particular cluster, data aggregation

and fusion are performed at cluster- head to reduce the

amount of data transmitting to the base station. Cluster

formation is usually based on remaining energy of

sensor nodes and sensor’s proximity to cluster -head [1]

Non cluster-head nodes choose their cluster- head righ

after deployment and transmit data to the cluster- head

The role of cluster-head is to forward these data and its

own data to the base station after performing data

aggregation and fusion. LEACH is one of the firsthierarchical routing protocols for WSNs.

III. LEACH AND LEACH-CLEACH (Low-Energy Adaptive Clustering Hierarchy)an energy-conserving routing protocol for wireless

sensor network.



International Journal ofVolume 2 Issue 11 pp 717-

Figure 1: Structure of clustured W

The idea is to form cluster of sensor no

signal strength and use the cluster-head a

forward data of other nodes in cluster to th

The data processing is performed at

LEACH is a dynamic clustering mechani

divided in rounds/intervals with equal le

beginning of the round, cluster-headsrandomly among the nodes which hav

energy higher than the average remaining

the nodes.

LEACH is done into two steps, the setup

steady state phase. In setup phase th

organized into clusters and CHs are sel

cluster heads change randomly over tim

balance the energy of the network. This

choosing a random number between 0 and 1

selected as a cluster head for the currentrandom number is less than the threshold

which is given by

In this formula, p is the percentage of clust

all nodes in the network, i.e., the probabilit

is selected as a cluster head; r the number

selection; and G is the set of nodes that ar

in round 1/p. As we can see here, the select

heads is totally randomly.

After becoming cluster heads, the nod

messages to all nodes to inform the status oCluster head nodes decide which cluster

based on the receiving signal strength of th

The cluster-heads create schedules and se

nodes in the clusters. For the rest of the rou

send data to their respective cluster head n

cluster- heads aggregate and send the dat

station.

After each round, clusters-heads are re-gen

cientific Research Engineering & Technolo23 February 2014 www.ijsret.org ISSN

IJSRET @ 2014

SN

es based on

s a router to

base station.

luster-heads.

sm. Time is

ngth. At the

is generated e remaining

energy of all

hase and the

nodes are

ected. These

in order to

is done by

. The node is

round if the value T (n),

r heads over

y that a node

of rounds of

not selected

ion of cluster

es broadcast

them. Non head to join

se messages.

nd to all the

nd, the nodes

des, then the

to the base

rated to form

new clusters. The cluster-hea

to spend energy equally betwe

it can lengthen the sensor net

LEACH-centralized (LEAC

LEACH in operation exceLEACH-C, the cluster head

BS. During the setup phase

nodes information about th

remaining energy levels. BS

level to determine the candi

node. The average node ene

node has remaining energy fa

be removed from the candidat

Using the candidate set, BS

simulated annealing algorithm

problem of finding k opti

algorithm attempts to minimicluster head nodes are deter

nodes the information inclu

clusters member node and

each cluster. Nodes use this i

TDMA slot for data trans

randomized rotation of the

position such that it rotates a

order to not drain the batte

addition, LEACH perform

“compress” the amount ofclusters to the base station,

dissipation and enhancing systSensors elect themselves to b

given time with a certain pro

nodes broadcast their status t

network. Each sensor node de

wants to belong by choosi

requires the minimum commu

the nodes are organized into

creates a schedule for the

allows the radio components

node to be turned off at al

transmit time, thus minimizinthe individual sensors. Once t

data from the nodes in its clu

aggregates the data and then

data to the base station. Since

in the scenario we are examitransmission. However, sinc

cluster-heads, this only affects

LEACH can achieve over a

energy dissipation compared

with the base station, when u

gy (IJSRET) 278 – 0882

d rotation allows network

en sensor nodes and hence

ork life time.

-C) [1] is similar to

pt cluster formation. In selection is carried out a

BS receives from other

ir current locations and

uses the remaining energy

date set for cluster head

rgy is computed and the

lling below this value wil

set.

finds clusters using the

[11] to solve the NP-hard

mal clusters [12]. This

e the total energy that non ined, BS broadcast to al

ding cluster head nodes

ransmission schedule for

formation to determine its

ission LEACH includes

high-energy cluster-head

ong the various sensors in

ry of a single sensor. In

local data fusion to

ata being sent from the further reducing energy

em lifetime. local cluster-heads at any

ability. These cluster-head

o the other sensors in the

ermines to which cluster i

ng the cluster-head tha

nication energy2. Once al

clusters, each cluster-head

odes in its cluster. This

of each non-cluster-head

l times except during its

g the energy dissipated in he cluster-head has all the

ster, the cluster-head node

transmits the compressed

the base station is far away

ing, this is a high energy e there are only a few

a small number of nodes

factor of 7 reduction in

to direct communication

ing the optimal number of




cluster-heads. The main energy savings of

protocol is due to combining lossy compre

data routing. There is clearly a trade-off

quality of the output and the amount of

achieved. In this case, some data from tsignals is lost, but this results in a substan

of the overall energy dissipation of the syst

IV. DISADVANTAGES OF LEAIn using LEACH protocol for cluster orga

features are still not supported. LEAC

homogeneous distribution of sensor nodes

area. This scenario is not very realistic. Let

scenario in which most of the sensor node

together around one or two cluster-heacluster formation algorithm will end up

more cluster member nodes A. This couldhead nodes a quickly running out of energy.

In addition, cluster heads are randomly

impossible the scenario illustrated in Figur

which two or even more cluster heads are

each other

Figure 2: Multiple cluster head in smal

In Figure 3, H1 and H2 is two cluster

▲and are their cluster members, respectiH2 are very closely located. Accord

communication model, the energy that a

consumes is the sum of that consumed in r

and that in sending data.

E ch = L Ebit N mem + L E (N mem +

+Lmd to Bs (1)

where L is the length of data, m the power

of transferring l bit of data, E bit the power

of processing 1 bit of data, Nmem th

members in a cluster, d to Bs the distance

cluster head and node Sink, LEelec Nme

that Nmem cluster members consume w

them send out length of l data to the clus

LENmem the power that the cluster he


IJSRET @ 2014

the LEACH

sion with the

between the

compression

e individual tial reduction

m.

H nization, few

assumes a

in the given

us consider a

are grouped

s LEACH’s by assigning

make cluster

selected, it

3 occurs, in

very close to

l region

heads, nodes

ely. H1 and ing to data

cluster head

eceiving data

1) + L E bit

consumption

consumption

number of

between the

m the power

hen each of

ter head, and

ad consumes

when it receives data of l

members. It follows from (1)

that cluster heads H1 and

transfer is:

Where Nmem1 and Nmem2 t

clusters H1 and H2, dh1toBs

between the two cluster heads

the total energy consumed by

E h1 + E h2 = L E bit (N m

mem1 + N mem2 + 2) + 2L

h2toBS )

When H1 and H2 are very clo

d h1toBS = d h2toBS

Then (4) becomes

E h1 + E h2 = LE bit (N memem1 + N mem2 + 2) + 2LE

As we can see, in this case th

of two clusters is only LE bit

the case that there is only onbecause LE bit + Lmd h1t

therefore, the total energy cotwo cluster heads is approxi

there is only one cluster head.

It is clear now that whenrandomly selected within a sm

loss occurs. The amount of lo

proportional to the number o

Of course, there is a precondit

is, cluster heads are very closebetween them becomes neglig

V. PROTOCOL PER

1. All senor nodes are identisame amount of initial eneenergy at the same rate an

residual energy and control

distance. Every node has t

different MAC protocol a

communication channels arconsumption of transferring d

is the same as that of transf

gy (IJSRET) 278 – 0882

ength l from its cluster

that the amount of energy

H2 consume during data

he number of members in

and dh2to Bs the distance

and node Sink, Therefore

he two clusters is

m1 + N mem2 ) +LE (N

bit + L m (d h1toBS + d

e, we can have

m1 + N mem2 ) + LE (N it + 2Lm d h1toBS

total energy consumption

+ Lmd h1tobs greater than

cluster head. In addition bs is much greater than

sumption when there are ately twice of that when

ultiple cluster heads are all area, a big extra energy

st energy is approximately

cluster heads in the area

ion on this conclusion, tha

ly located and the distance ible.

ORMANCE

cal and charged with the rgy. All nodes consume

are able to know thei

transmission power and

he capability to suppor

d data processing. Al

identical. The energy ta from node A to node B

rring the same amount of




date from node B to node A.

2. Every node can directly communicat

other node

4. Every node has data to transfer in ever

Thedata transferred by sobering nodes arcan be fused.

5. Sensor nods are static.

WSNs are autonomous networks. Sens

independent with each other. The coordin

nodesis done through wireless communi

costs much. This is one of the major rea

LEACH protocol selects cluster heads rand

discussed before, this approach may cause

energy because of unbalanced cluster head

To solve this problem, we propose a new

selecting cluster heads. We assume that:1. The network satisfies the pre-conditions

LEACH protocol.

2. After deployment, sensors are able t

positions through GPS, or before depl

positions are accurately decided.

3. All nodes are able to adjust data transm

If necessary they can communicate with the

to acquire the initial setting information of t

If we modify the procedure of the calcula

during the cluster head generation such that

are produced progressively, then a node c

it is suitable to be a new cluster headlocations of existing cluster heads and its

More specifically, if the node is very

existing cluster head, then this node will

attempt to be a cluster head.

As shown in Figure the network is divid

parts. Nodes in region G1 will compete

cluster head. When a node is selected as a c

will broadcast the information to nodes nea

region G2 will receive the message. Thus,

this region compete for being cluster head

information of the cluster head in regioninto consideration. If a node in G2 is close

head in G1, the node will be discarded. The

in all other regions will be generated in the

The cluster heads generated with this appr

be close to each other. However, becausequit the competition for cluster head, the to

cluster heads can be reduced, which is

saving the network energy. Our approach t

problem is when a node is excluded in the

selection, a message is broadcast to other


IJSRET @ 2014

with every

time frame.

related and

r nodes are

tion between

ation, which

sons that the

omly. As we

the waste of

distribution.

approach to

f applying

know their

yment, their

ission power.

base stations

he network.

tion of T (n)

cluster heads

uld decide if

ased on the wn location.

lose to any

give up the

ed into three

for being a

luster head, it

rby. Nodes in

hen nodes in

, the location

1 will taken to the cluster

cluster heads

ame way

ach will not

some nodes tal number of

ot good for

solving this

cluster head

nodes and T

(n) will be modified to increa

nodes being selected as cluste

is

K is the number of nodes t

cluster head selection due to t

initial value of 0. When k in

well, which will ensure suf

heads will be generated by the

Figure 3: Selectin

To facilitate the explanation

we introduce the following no

Bs The base station or node Si

Si The i-th sensor node

Hj The j-th cluster head

Mem (Cj) Members of the j-th

Mem (Cj)I The i-th membersLoc (Si) Location of the i-th s

Delay (Si) Time delay that the

start to compete for a cluster h

Num(Giveup) Number of disc

|| Operation of concatenation

To evaluate the performance

100 X 100 network configurat

each sensor node is assigned

the amount of transmission enamplifier energy (E amp ) is 1

performance evaluation are

energy consumption and data

of nodes alive. Each performa

varying the number of cluster-To determining quality of dat

amount of data (number of d

gy (IJSRET) 278 – 0882

e the probability of others

heads .The modified T(n)

at are excluded from the

e location reason, with an

reases, T (n) increases as

ficient number of cluster

progressive algorithm.

cluster heads

f our improved algorithm

ations:

nk

cluster

f the j-th cluster nsor node

i-th sensor node

ead

arded cluster heads

f LEACH, we consider a

ion with 101 nodes, where

an initial energy of 2.0 J

rgy is 50 nJ /bit , transmi 00 pJ /bit. The criteria for

the network lifetime, the

aggregated at BS and no

ce criteria is evaluated by

heads from 1 to 8. a we need to measure the

ata signals represented by




IJSRET @ 2014

an aggregate signal) received at the base station. We

tracked the rate at which the data are transferred to the

base station and the amount of energy required to get the

data to the base station.

VI. CLUSTER HEAD SELECTION:After the deployment of sensor nodes, we first acquire

all nodes’ location information (through GPS technologyor known prior to its deployment) and report it to the

base station. The base station decides Delay (Si) for

every node based on the geographic distribution of all

sensor nodes. Delay (Si) = 0 for those in the region to

start first. As illustrated in Figure 4, nodes in G1 start to

compete for cluster heads at time 0, then nodes in G2

start with a delay, and then nodes in G3 start with a

delay after nodes in G2 are finished, and so on. During

the process, nodes need to send their locationinformation to the base station:

SRiR BS: Loc (SRiR)

The base station needs to send the delay information to

each node:

Bs SRiR: Delay (SRiR)

Set Num (Giveup) to 0. Start with the nodes in G1. If a

cluster head is generated from G1, broadcast a Hello

package and Num (Giveup).

Hj broadcast: Hello, Num (Giveup)

When nodes in G1 are finished, consider nodes in G2.

Now the cluster heads generated in G1 are referencepoints. The distance between a node in G2 and any

cluster head in G1 is a factor in selecting the node as a

cluster head, as well as the random value of T (n). If all

conditions are satisfied, then broadcast the Hello

message and Num (Giveup).Hj -> broadcast: Giveup, Num (Giveup)

Otherwise, only broadcast Num (Giveup). When nodes

in other region receive this message, they will increment

Num (Giveup) by 1, and then modify T (n) to increasethe probability of being selected as cluster head. Repeat

the above process until all nodes in the network areconsidered.

VII. SIMULATIONSIn this section, we evaluate the performance of My

LEACH protocol implemented with MATLAB 100

sensor nodes are randomly distributed in an area of 100

m x 100 m. BS is put at the location with x = 175, y =

50.The bandwidth of data channel is set to 1 Mbps, the

length of data messages is 500 bytes and packet header

for each type of packet was 25 bytes. The number round

is set to 500s. When a node uses energy down to its

energy threshold, it can no longer send data and is

considered as a dead node.

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IJSRET @ 2014

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a modified energy efficient communication protocol for wireless sensor network

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