Enhanced Leach Protocol

ISSN (e): 2250 – 3005 || Volume, 05 || Issue, 05 || May – 2015 ||
International Journal of Computational Engineering Research (IJCER)
www.ijceronline.com Open Access Journal Page 31
Enhanced Leach Protocol
1
Girish Prabhu, 2
Dr.G.R.Udupi
1,2
Dept of Electronics and Communication, Gogte Institute of Technology, Belgaum,India,
I. Introduction
A Wireless Sensor Networks (WSN) is a set of thousands of micro sensor nodes that are capable of
sensing, communicating between each other and performing computational and processing operations. Wireless
Sensor Networks can provide great advantages with respect to low-power, low-cost and fast deployment for
many applications without human supervision[1]. Energy efficiency is one of the most important issues while
designing protocols which are lifetime critical. Sensor nodes are equipped with tiny batteries with limited
power. They can be randomly dropped or deployed manually. Organizing the wireless network in efficient and
scalable manner is by using the clusters. Cluster head (CH) is responsible for information gathering by the nodes
of its cluster and may aggregate and compress the data before transmission to sink. However, this results in a
higher rate of energy utilization by cluster heads. The most popular clustering method is LEACH, which
addresses clustering energy problem by probabilistically changing the role of cluster head among all nodes. The
probability of becoming a cluster head should be selected wisely to increase the performance of the network.
The main focus of this paper is to address energy problem and developing a method for selection of cluster head
with the optimal probability from the point of minimizing the energy consumption [2].
II. Literature review
Firstly sensor networks were mainly used by military applications but later have been considered for the
applications such as environmental monitoring, health monitoring etc. A sensor network design is motivated by
many factors, which include Fault Tolerant Communication, Scalability, Power Consumption, Data Delivery
Models, Data Aggregation/Data Fusion, Node Deployment. LEACH is the network protocol used to increase
the lifetime of the network by using hierarchical routing for wireless sensor. All the nodes in a network
formulate themselves into local clusters, with one node performing as the cluster-head. All non-cluster-head
nodes transmit their data to the cluster-head. While the cluster-head node performs data processing like data
aggregation and then transmits data to the remote base station. Therefore, cluster-head node is much more
energy-intensive than other nodes of cluster. Thus, when a cluster-head node dies all the nodes that cluster lose
communication ability with base station. LEACH incorporates probabilistic rotation of the high-energy cluster-
head in order to avoid exhausting the battery of any one sensor in the cluster. In this way, the energy load of a
cluster-head is evenly distributed among the nodes of the cluster. Since the cluster-head knows all the member
nodes, it will create a TDMA schedule for each node, which tells the nodes exactly when to transmit its data.
Using a TDMA for data transfer avoids intra-cluster collisions. The cluster head is responsible for the transfer of
the data to the base station.
Abstract:
Technological advances in wireless sensor networks have made impact on everyday life. In
wireless sensor networks energy is main concern & it is considered while designing sensor
networks. We use hierarchical routing protocols based on clustering because of balanced
energy consumption and scalability. The efficient usage of energy in a sensor node is most
important parameter to increase the life time of wireless sensor network. In this paper we
analyze the design issues constructing the cluster in the wireless sensor networks and detail
working of LEACH (Low Energy Adaptive Clustering Hierarchy) protocol and its
SIMULATION .The results reveal the measure for performance of sensor networks.
Keywords: Cluster head, Data aggregation, Energy efficient, Hierarchical routing, LEACH,
Life time, Wireless sensor network

Enhanced Leach…
III. Leach protocol
Low Energy Adaptive Clustering Hierarchy (LEACH) protocol for sensor networks is proposed by W.
R. Heinzelman which tries to minimize energy dissipation in wireless sensor networks. The arrangement of
clusters is done depending on the of the received signal strength. The main purpose of LEACH protocol is to
provide data aggregation for sensor networks. In LEACH protocol the total nodes are divided into many small
groups called clusters for proportional distribution of power consumption inside the network. The cluster
formation will be done as shown in the figure1 [3]
Figure 1 Cluster formation
The cluster head can be selected randomly and then rotate this role probabilistically to evenly distribute the
energy load among the sensors in the cluster. The node n chooses a random number between 0 and 1 and the
nodes becomes a cluster head for the current round if the number is less than the threshold T (n).
Where, p- the desired percentage of cluster heads (e.g. 0.05),
r - the current round
G- the set of nodes that have not been cluster heads in last 1/p rounds.
There is only 5% of the nodes need to act as cluster head which act as a router to the base station.
The cluster head (CH) nodes receives the data and compress all the data coming from nodes that belong to the
respective cluster, and sends an aggregate data to the base station. Data aggregation is performed to minimize
the amount of information that must be transmitted to the base station. Data aggregation is performed local to
the cluster[4]. This protocol is divided into rounds and each round consists of two phases:
A. Setup phase
1. Advertisement phase
2. Cluster Set-up phase
B. Steady phase
1. Schedule creation
2. Data transmission
The setup consists of three steps. In Step 1 (advertisement step), nodes independently and probabilistically
decide whether or not to become a CH for the current round .The nodes sends a broadcast message as
indication of becoming CH, the message can heard by everyone in the network. To avoid collision, a carrier
sense multiple access protocol is used. In Step 2 (cluster joining step), the remaining nodes join a cluster based
on the largest received signal strength of an advertisement message, and inform their intention to join cluster by
sending a join request message. Once the CHs receive all the join requests, Step 3 (confirmation step) the CHs
broadcasts a message informing time slot schedule to be used by their cluster member nodes for
communication. Once the clusters are set up, the network goes to steady-state phase, where actual
communication between sensor nodes and the BS takes place. Each node knows its time slot, to transmit
information. The CHs combines the messages from all their cluster members, aggregates the information and
sends the result to the BS. The steady-state phase comprises of multiple reporting cycles, and will be of much
longer time compared to the setup phase [5].
When n k-bit of messages has gathered by cluster head in its cluster then it compresses the data to a µ (n * k) –
bit message and sends this message to base station, where µ≤1 is the compression coefficient [6].

Enhanced Leach…
Figure 2 Time line of leach protocol
Figure 3 Cluster formation process
IV. Analysis of simulation and results
The simulation shows performance evaluation of LEACH protocol in terms of number of dead nodes.
With this simulation results the life time of LEACH protocol can be studied. The graph in the fig.5 shows the
number of alive nodes in the network. Initially there were zero dead nodes in the network. But when
transmission starts the number of dead nodes increases immediately. The energy consumption by the nodes
increases and finally attains zero.
Figure 4 Field distribution
Figure 5 shows the initial field distribution of the network implementation. A 100m*100m field has been
considered and nodes are randomly placed in the field. The base station, which is denoted by a ×, is placed at the
center of the field. Here, the cluster head are shown by a plus symbol (+) and other nodes by a circle. All the
nodes are alive in the network.

Enhanced Leach…
Figure 5 Simulation result – alive nodes
V. Conclusion
In this paper we analyze the LEACH protocol, an existing protocol architecture for wireless sensor
networks that incorporates the concepts of energy efficient cluster based routing together with data aggregation
to achieve required performance. We can implement LEACH protocol on both ns2 and MATLAB platform to
evaluate the performance of LEACH protocol.
References
[1]. Wikipedia,"Wireless Sensor Networks , ”http://en.wikipedia.org/wiki/Wireless_sensor_network
[2]. Dr. R. R. Mudholkar, Dr. S. R. Sawant, V. C. Patil, Rjshree. V. Biradar “Classification & Comparison of Routing Protocols in
WSN” UbiCC Journal- Vol 4
[3]. Ian F. Akyildiz, Weilian Su, Yogesh Sankarasubramaniam, Erdal Cayirci: “ A Survey on Sensor Networks”, IEEE
Communication Magazine, pp. 102-114(August 2002)
[4]. Amrinder Kaur,Sunil Saini, “Simulation of Low Energy Adaptive Clustering Hierarchy Protocol for Wireless Sensor Network”
[5]. Sunil Pariyani, Rajesh Patel, Vijay Ukani,” Energy and Throughput Analysis of Hierarchical Routing Protocol(LEACH) for
Wireless Sensor Networks”, International Journal of Computer Applications Volume 20- No. 4 (April 2011)
[6]. Yuh Ren Tsai, “Coverage Preserving Routing Protocols for Randomly Distributed Wireless Sensor Networks”, IEEE
Transactions on Wireless Communications, Volume 6- No. 4 (April 2007)

Enhanced Leach Protocol

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