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Leach protocol in wsn
LEACH (Lower Energy Adaptive Clustering Hierarchy) protocol is a grade routing protocol for wireless sensor networks leach protocol ppt free download
LEACH Media Access
• LEACH (Lower Energy Adaptive Clustering Hierarchy) protocol is a
grade routing protocol for wireless sensor networks in which:
– The base station (sink) is fixed
– Sensor nodes are homogenous
• LEACH conserves energy through:
o Adaptive Clustering
• LEACH also uses CDMA so that each cluster uses a different set of
CDMA codes, to minimize interference between clusters.PROPERTIES
Properties of LEACH Protocol include:
• Cluster based
• Random cluster head selection each round with rotation.
• Cluster membership adaptive
• Data aggregation at cluster head
• Cluster head communicate directly with sink or user
• Communication done with cluster head via TDMA
• Threshold valueOPERATION
LEACH protocol has two phases:
Set up phase
• The phase in which cluster heads are chosen.
Steady State phase
• The phase in which cluster head is maintained.ARCHITECTURE
Cluster Head Selection
Steady State Phase
LEACHC: BS Cluster FormationCluster Head Selection
The selection of cluster heads will be done by the following equation:𝑇
Where, p is the probability of the nodded being selected as a clusterhead node;
R is the number of rounds passed;
G is the collection of ordinary nodes; mod denotes modulo operator, and
T (n) is the threshold value of the selection of cluster heads in each roundCluster Formation
• Cluster Heads broadcasts an advertisement message (ADV) using CSMA MAC
ADV = Node’s ID + distinguishable header.
• Based on the received Signal strength of ADV message, each noncluster Head node
determines its Cluster Head for this round.
• Each noncluster Head transmits a joinrequest message (JoinREQ) back to its chosen
cluster Head using a CSMA MAC protocol.
JoinREQ = Node’s ID + ClusterHead ID + Header.
• Cluster Head node sets up a TDMA schedule for data transmission coordination within
• TDMA Schedule
Prevents collision among data messages.
Energy conservation in non clusterhead nodes.Steady State Phase
TDMA schedule is used to send data from node to cluster head.
Cluster head aggregates the data received from nodes in the cluster.
Communication is via directsequence spread spectrum (DSSS) and each
cluster uses a unique spreading code to reduce intercluster interference.
Data is sent from the cluster head nodes to the BS using a fixed spreading
code and CSMA.• Assumptions
o Nodes are all time synchronized and start the setup phase at
o BS sends out synchronized pulses to the nodes.
o Cluster Head must be awake all the time.
• To reduce intercluster interference, each Cluster in LEACH
communicates using directsequence spread spectrum (DSSS).
• Data is sent from the Cluster head nodes to the BS using a fixed
spreading code and CSMA.FLOWCHART OF STEADY STATE PHASELEACH C: BS Cluster Formation
Uses a central control algorithm to form clusters.
• During set up phase each node send s its location
and energy level to BS.
• BS assigns cluster heads and clusters.
• BS broadcasts this information.
• The Steady state phase is same as LEACH.LEACH MEDIA ACCESSSIMULATION
There are many both opensource and commercial network
simulators for LEACH such as:
• ns (open source)
• OPNET (proprietary software)
• NetSim (proprietary software)
• OMNeT++ (IDE)
• TinyOS (open source)
The various advantages of LEACH protocol are:
• The Cluster Heads aggregates the whole data which lead to
reduce the traffic in the entire network.
• As there is a single hop routing from nodes to cluster head it
results in saving energy.
• It increases the lifetime of the sensor network.
• In this, location information of the nodes to create the cluster
is not required.DISADVANTAGES
The various disadvantages of LEACH protocol are:
• LEACH does not give any idea about the number of cluster heads in the
• One of the biggest disadvantage of LEACH is that when due to any
reason Cluster head dies, the cluster will become useless because the
data gathered by the cluster nodes would never reach its destination i.e.
• Clusters are divided randomly, which results in uneven distribution of
• LEACH is completely distributed
– No centralized control system
• LEACH outperforms:
– DirectTransmission in most cases
– MTE in many cases
– Static clustering in effectively all cases
• LEACH can reduce communication costs by up to 8x
• LEACH keeps the first node alive for up to 8x longer and the last
node by up to 3x longerAny queries
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