WIRELESS SENSOR NETWORK Direct communication with BS Minimum energy multi-hop routing Clustering LEACH

1. LEACH CLUSTER-BASED
ROUTING PROTOCOL FOR
WIRELESS SENSOR
NETWORKS

2. WIRELESS SENSOR NETWORK
 A Wireless Sensor Network (WSN) of spatially distributed
autonomous sensors to monitor physical or environmental
conditions, such as temperature, sound,
pressure,humidity,wind direction and speed,vibration
intensity,power-line voltage, etc. and to cooperatively pass
their data through the network to a main location. Provide a
bridge between the real physical and virtual worlds Allow the
ability to observe the previously unobservable at a fine
resolution over large spatio-temporal scales Applications in
Disaster,Surveillance,Agriculture,etc

3. Direct communication with BS
 •Each sensor sends its data directly to the base
station.
 •Possibly optimal if either the base station is
close to the nodes, or the energy required to
receive data is large.

4. Minimum energy multi-hop routing
•Nodes route data destined ultimately for the base station through
intermediate nodes.
•The intermediate nodes are chosen such that the transmit amplifier
energy is minimized.
•Rather than just one (high-energy) transmit of the data, each data
message must go through n (low-energy) transmits and n receives
•Shorten system lifetime as the nodes closest to the base station are
the ones to die out first since they are the ones most used as
“routers” for other sensors’ data.

5. Clustering
•Nodes are organized into clusters that
communicate with a local base station, and these
local base stations transmit the data to the global
base station, where it is accessed by the end-user.
•If the base station is an energy-constrained node,
it would die quickly, as it is being heavily utilized.

6. LEACH
•Low-Energy Adaptive Clustering Hierarchy
•Clustering-based protocol
•Select sensor nodes as CHs by rotation, so
the high energy dissipation in communicating
with the BS is distributed evenly to all sensor
nodes in the network.

7. Figure: LEACH protocol

8. Assumption
 •The base station is fixed and located far from
the sensors.
 •All nodes in the network are homogeneous
and energy constrained.

9. Key Features
 •Localized coordination and control for
set-up and operation.
 •Randomized rotation of the cluster “base
stations” or “cluster-heads” and the
corresponding clusters.
 •Local compression to reduce global
communication.

10. LEACH
 •The nodes organize themselves into local clusters, with one node
acting as the local base station or cluster-head.
 •Cluster-head nodes broadcast their status to the other sensors in the
network.
 •Each sensor node determines to which cluster it wants to belong by
choosing the cluster-head.
 •Each cluster-head creates a schedule for the nodes in its cluster.
 • Once the cluster-head has all the data from the nodes in its cluster,
the cluster-head node aggregates the data and then transmits the
compressed data to the base station.