Sensor network Routing protocol

A study on LEACH protocol and how to improve it

Typical applications of Sensor Networks

• Reliable environment monitoring for commercial and military applications– For a security system, acoustic, seismic and

video sensors can be used to form an adhoc network to detect intrusion.

• Monitor machines for fault detection and diagnosis

The Microsensor Networks

• Large number of participants (hundreds of thousands)

• Nodes are randomly and statically distributed .

• Limited resources (computing and battery power)

Key Features of LEACH (Low-Energy Adaptive Clustering Hierarchy)

• Localized coordination and control for cluster set up and operation.

• Randomized rotation of the cluster “base stations” or “ cluster heads” and the corresponding clusters.

• Local compression to reduce global communication

Dynamic Cluster

LEACH - Algorithm Details

• The operation is broken up into rounds– Advertisement phase

• use CSMA MAC protocol, and all cluster heads transmit with same energy

– Set up phase : Cluster is organized• each node transmits to which cluster head it wants

to belong to using a CSMA MAC

– Steady State Phase: Data Transfers to Base Station occur (TDMA and CDMA are used)

How is LEACH Energy Efficient ?

• Energy requirement is distributed among all the sensors – increases system lifetime.

• Local computation (data fusion) reduces amount of data to be transmitted to the base station (computation is cheaper than communication) .

• Reduces the transmission power for participating nodes .

• Allow nodes to be switched off when not transmitting data.

System lifetime comparison

A simulation study on LEACH

• Aim: to find a way to improve LEACH

• OMNet++ is used in my dissertation.

• Solar nodes are added to the network to improve the energy dissipation

• The performance of the network is examined with various numbers of solar nodes.

Program details

• In this program, there are 100 sensor nodes randomly distributed in a 1000x1000 field.

• The transmission power is set to be 190j/frame• The assumption made is that each node knows

its exact location (represented by x and y coordinates)

• Assumes that Solar nodes uses 95j to transmit a frame.

Flow Diagram

Network Simulation picture

Node Details

BS sending ClusterHeadMessage

Nodes send data to CH

Examine the performance

• To examine the performance of LEACH, I firstly set the number of solar nodes to be 0. and run the simulation for 10 times.

• Then I took a look at the simulation end time in each run, and computed the average simulation end time, and it is 78052 seconds.

• Also I recorded the time when the first node is dead, and the time when half of the nodes are dead.

• After that, I took a look at the energy level on each node, and see how it is dissipated

See how the solar nodes helps

• To see how the solar nodes improves the performance of LEACH:

• Change the number of solar nodes to 5, 10, 15, 20, 25. with each parameter, run the simulation for 10 times, and record the simulation end time, first dead time, the half dead time, and the residual energy on each node.

Simulation End time picture

Node residual energy picture

Results

6428517812120 Solar N

6566320214425 Solar N

6413516710415 Solar N

652551448310 Solar N

71116123715 Solar N

78152101650 Solar N

SimEndTHalfDeadTFirstDeadT

How to improve LEACH

Further study

• Localized cluster head initialization and re-election. Thus, reduce the global traffic and the computation work load on the base station.

• Thank you for your time!