International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 6 - Jun 2014
A Review of Clustering Protocols in Wireless Sensor
Networks
Monu rani #1, Kiran gupta#2, Amit Chhabra#3
#1
M.Tech (Student),#2Assistant Professor,#3Head of Department
Computer Science Department
Swami Devi Dyal Group Of Professional Institutions,
Barwala, Distt: Panchkula (Haryana) – 134009
Krukshetra University krukshetra Haryana (126102) India
Abstract— Protocols are more beneficial in power saving. In
cluster-based routing, a cluster head is selected to approximate
the data received from root nodes and forwards the information
to the base station. In Wireless Sensor Networks (WSNs),
minimizing the power consumption of available resources is
great issue remain unsolved. To save power consumption many
types of routing protocols are developed. In these protocols,
cluster-based routing cluster heads should be accurate to save
power. In this proposed paper, various types of E-LEACH (Low
energy adaptive clustering hierarchy) protocol with ALB
(Adaptive load balance) technique are discussed.
Converters
Processing Unit
(Microcontroller)
DAC
Communication
Unit
Transmitter
ADC
Reciever
Sensing
Unit
Storage
(Memory)
Sensor 1
Power Supply
(Lithium battery)
Sensor 2
Keywords— WSNs (Wireless Sensor Networks), CH (Cluster Head),
LEACH (Low Energy Adaptive Clustering
Protocol), ADC
(Analog To Digital Converter ), DAC (Digital To Analog Converter).
I. INTRODUCTION
A WSN contains different types of sensor nodes that are used
to detect and transfer the data wirelessly to the base station or
the next receiver node. The technology advancements made it
possible to minimise the cost and the bulkiness of the
electronic devices. To monitor the different conditions a wide
range of sensors are available such as humidity, movement,
temperature, pressure, and lightening conditions. The required
lower Power consumption restricts the sensor to use the
limited resources such as less low transmit power, memory
requirement and less processing calculation. The aim of this
research is to find an power efficient routing protocol for
Wireless Sensor Networks. The aims is to provide a better
end-to-end delay, less number of dead nodes, a higher output,
and overall lower power consumption compared to other
protocols.
A state-of-the-art technology Wireless Sensor Networks
(WSNs) is used to sense the data from all locations. Different
parts of sensor nodes can be classified in six major units:
1) Communication Unit
2) Processing Unit
3) Sensing Unit
4) ADC/DAC Converters
5) Power Supply
6) Temporary Storage Unit
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Figure 1: Typical Wireless Sensor Node Architecture
Fig.1 shows the general architecture of senseor node.The
sensors in the sensing unit interact physically with the
environment. Output of sensing unit is send to the ADC/DAC
converters for analogy to digital conversion. The microcontroller in processing unit receives this digital data and does
the required processing by using the temporary memory. The
processed data are then transmitting to the transmitter of the
communication unit for transmission towards the cluster head.
On the other hand, the data from the Cluster Head is received
by the receiver and then transferred to the processor for
further processing. The power source used in sensor node can
be a lithium battery. The two main parts where most of the
power consumption occurs are:
1) The processing units and
2) The communication Unit.
The cluster head is either a mobile or fixed node, which has
the capability to connect the sensor network to the internet
where the user can access and process the data. Routing in
WSNs is very essential due to the inherent traits that
distinguish this network from other wireless networks or
cellular networks. Power Consumption of sensor nodes is
necessary point on WSNs. Limited memory and power are
other parameters which affect the amount of data to process or
store in an individual node. The architecture of typical WSN
is shown in Figure 1.2.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 6 - Jun 2014
Figure 2: Wireless Sensor Network
The utilization of WSNs in different areas including industry,
commercial sector, or military fields is increasing rapidly all
over the world. Healthcare becomes the area in industry and
commercial sector where WSNs are used. The wearable and
implant sensors help the healthcare professionals to monitor
the patient’s vital signs.
II. TYPES OF LEACH PROTOCOLS
A. LEACH-Centralized (LEACH-C)
The conventional LEACH protocol does not guarantee the
best possible number of CHs and their effectual locations.[1]
The problem is due to the clusters formation method used by
the LEACH algorithm. LEACH-C is therefore proposed to
enhance the cluster creation part of the LEACH protocol.
All nodes are required to send their ID, location, and energy
information to the base station during the setup phase of
LEACH-C. The central control algorithm first specifies the
average power level and then compares that energy level to
the energy level of the received signal power. The base station
picks the optimal number of CHs from the nodes with an
energy level greater than the average power level. A list of
IDs of these selected nodes is transmitted by the base station
to all nodes. We here have taken following assumptions are:
1. Every node can calculate its energy.
2. Every node knows its location.
3. Every node can communicate to the base station.
B. MULTI-HOP LEACH
The formation of clusters and selection of the CHs is done in
the setup phase.[6] During steady state phase, the non-cluster
head nodes send their data to the CHs. The random selection
of CHs is the same as in LEACH. The most feasible and
power efficient path is selected for that CH which is far from
the base station. The method used for the selection of
intermediate CH is the distance between the CH and the base
station. The CH closer to the base station receives the data
from the other CH which is far from base station. This helps
to save power of those CHs which belong to the clusters with
larger distance from the base station as higher transmission
power cost is required for communication with larger
distances.
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Figure 3 : Multi-Hop LEACH Architecture
C. STABLE ELECTION PROTOCOL (SEP)
The nodes selected as CH consumes more power due to
performing additional functions that results in early death of
these nodes. The stability region, time interval before the
death of first node, is low in these protocols. The nodes with
higher initial energies are called advanced nodes. we are
considered some assumptions:
1.
2.
3.
4.
5.
A percentage of the total number of sensor nodes
contains additional power resources.
The deployment of sensor nodes is randomly and
uniformly distributed.
All the nodes are static.
Sink is placed in the centre of the sensor field.
The dimensions of sensor field are given.
SEP considers the weighted election probabilities of the nodes
in which the advanced as well as normal nodes are selected as
cluster heads to ensure the balanced power consumption.
[3]The residual power is used as a parameter for the selection
of the cluster heads.
D. SOLAR-AWARE LEACH (S-LEACH)
The life span of WSNs can be improved by using solar panels
with sensor nodes. The solar-aware LEACH protocol is
proposed for application specific WSNs to tackle these
situations. Some nodes are enhanced with solar power in sLEACH. The nodes with solar power are stronger candidates
for the selection of CHs. The concepts of LEACH and
LEACH-C (discussed earlier in this section) are used in sLEACH protocol.
E. SOLAR-AWARE CENTRALIZED LEACH
The nodes driven by a solar power system are given priority
for the selection of CHs due to their higher residual energy.
[5]All nodes in s-LEACH send their solar power status along
with their ID, location, and power information to the base
station. S-LEACH uses the same CH selection criteria as in
LEACH-C (i.e. nodes with higher power will be chosen as
CHs). The addition of solar-aware nodes helps to improve the
performance of the entire network. The network performance
and the life span of solar-aware nodes depend upon the
duration of the node’s exposure to the sun.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 6 - Jun 2014
F. MOBILE-LEACH (M-LEACH)
M-LEACH is proposed with the mobility support of sensor
nodes. [4] LEACH follows a non-realistic consideration that
the power and radio characteristics of all nodes are fixed and
homogenous. In each cluster, CH deals with a different
number of member nodes. The changes proposed by MLEACH during setup phase for the selection of the cluster
heads are given below.
1.
2.
The nodes with more residual power are preferred.
In terms of mobility, nodes with lower speed are
preferred.
3. The nodes with lower attenuation power are
preferred.
The basic rule of power based transmission is the transmitted
signal power multiplied by
Attenuation equals the received signal energy, as shown in
equation (1)
G. LEACH SELECTIVE CLUSTER (LEACH-SC)
The main task of CH is to route the member nodes data to the
base station. Even when the member node is closer to the base
station than its CH, according to previous methods the node
must send data to its CH first. The CH then transmits the same
data to the base station.[2] The LEACH-SC mechanism
resolves this issue, which results in lower power cost of the
sensor nodes and prolongs the network life. Like LEACH, the
LEACH-SC procedure works in rounds. Each round consists
of setup and steady state phases. LEACH-SC improves the
cluster formation portion of the setup phase. An enhanced
cluster head formation algorithm is given in which only
selected CHs transmit their IDs and location information to all
nodes. The nodes receive this information based on their
location. The information from the CH is received only by
those nodes that are in that CH coverage range. The nodes
choose only that CH which is closest to the base station and
their own centre point.
III. CONCLUSION
Preceive= Ptransmit /
ra
(1)
Where
r = distance of transmission
a= RF attenuation constant
The value of ‘a’ is between 2 to 5 depending upon distance
and transmission environment. The selection of CH is done in
M-LEACH by using the following method.
N is a variable that denotes the number of sensor nodes in a
sub-area. The (X, Y) coordinates of each node I am
represented by (xi, yi). The distance from CH to node I is
represented by did. The transmission attenuation of node I can
be calculated by using equation (2). The value of sj for subarea j is calculated by equation below.
Sj=
(2)
The best possible location of CH in the sub-area can be found
by using below equations.
xjc=
(3)
c
yj =
Here we discuss in Wireless Sensor Networks (WSNs),
minimizing the power consumption of available resources is
great issue remain unsolved. To save power consumption
many types of routing protocols are discussed. In multi hop
leach save power of those CHs which belong to the clusters
with larger distance from the base station as higher
transmission power cost is required for communication. SEP
considers the weighted election probabilities of nodes in
which the advanced as well as normal nodes are selected as
cluster heads to ensure the balanced power consumption.
Solar aware leach helps to improve the performance of the
entire network. Network performance and life span of solaraware nodes depend upon the duration of the node’s exposure
to the sun. Finally,cluster-based routing cluster heads should
be accurate to save power in WSN.
REFERENCES
[1] JiaXu , NingJin, XizhongLou, TingPeng, Qian,Zhou, YanminChen,
“Improvement LEACH protocol for WSN”, IEEE-2012 9th International
Conference on Fuzzy Systems and Knowledge Discovery, 2012pp2174-2177.
[2] Wang Jun, Nanjing, China, Zhang Xin, Xie Junyuan, Mi Zhengkun “A
distance-based clustering routing protocol in wireless sensor networks.”
(4)
The nodes with lower mobility are preferred to become CHs.
The cost factor given in equation below is used for node I to
become CH.
(5)
[3] Femi A Aderohunmu, Jeremiah D Deng “An Enhanced Stable Election
Protocol (SEP) for Clustered Heterogeneous WSN.”
[4] L. T. Nguyen, X. Defago, R. Beuran and Y. Shinoda, "An Energy
Efficient Routing Scheme for Mobile Wireless Sensor Networks," in IEEE
ISWCS, 2008.
[5] Islam, M.J; Khulna Univ. of Eng. & Technol., Khulna ; Islam, M.M. ;
Islam, M.N. “A-s-LEACH: An Advanced Solar Aware Leach Protocol for
Energy Efficient Routing in Wireless Sensor Networks”
[6] N. Israr and I. Awan, "Multi hop clustering Algorithm for load balancing
in Wireless Sensor Networks," International Journal of Simulation, Systems,
Science and Technology, vol. 8, no. 1, pp. 13-25, 2007.
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