Transcript 1426794819-Aeon_LEACH-Vidhi

Aeon LEACH
An Efficient LEACH protocol in Heterogeneous
and Homogenous Wireless Sensor Networks
Under Guidance Of: Dr. Mohammad Mozumdar
Presented By
: Vidhi Nagri
WSN Applications
• Top 10 Emerging Technologies
• Variety of purposes like military surveillances, habitat monitoring,
forest fire detections, and landslide detections
• Ad-hoc deployed sensors, each capable of detecting ambient
conditions like temperature, sound, movements, light, or the
presence of particular objects.
• Routing algorithms can be categorized into three types
1) Direct transmission algorithms
2) Hop to hop transmission algorithms
3) Cluster based algorithms
What is LEACH??
• LEACH (Low-Energy Adaptive Clustering Hierarchy), a clustering-based
protocol that utilizes randomized rotation of local cluster base stations
(cluster-heads) to evenly distribute the energy load among the sensors in
the network.
– The base station (sink) is fixed
– Sensor nodes are homogenous
• LEACH conserves energy through:
– Aggregation
– Adaptive Clustering
Communication Protocol in WSN
• Direct transmission : Sensor node directly transmits data to the BS
• Minimum-transmission-energy : Electing the minimum transmission
energy consumption path for data transmission based on the proportion of
successful data transmissions, the number of channel events, the remaining
node energy of nodes, and the traffic load of nodes.
• Multihop routing : Communication between two end nodes is carried
out through a number of intermediate nodes whose function is to relay
information from one point to another.
• Static Clustering : Cluster head is fixed, nodes pass the data to CH and
CH transmit the data to BS.
Radio Model
• Designed around
acceptable Eb/N0
• Eelec = 50nJ/bit
– Energy dissipation for
transmit and receive
• εamp = 100pJ/bit/m2
– Energy dissipation for
transmit amplifier
ETx (k , d )  ( Eelec * k )  ( amp * k * d 2 )
ERx (k )  Eelec * k
• k = Packet size
• d = Distance
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Direct-Transmission
• Each sensor node
transmits directly to
the sink, regardless of
distance
• Most efficient when
there is a small
coverage area and/or
high receive cost
Sensor Status after 180 rounds
with 0.5J/node
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Minimum Transmission Energy (MTE)
• Traffic is routed through
intermediate nodes
– Node chosen by transmit
amplifier cost
– Receive cost often ignored
• Most efficient when the
average transmission
distance is large and Eelec is
low
Sensor Status after 180 rounds
with 0.5J/node
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Static Clustering
• Indirect upstream traffic
routing
• Cluster members transmit
to a cluster head
– TDMA
• Cluster head transmits to
the sink
– Not energy-limited
• Does not apply to
homogenous
environments
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LEACH: Adaptive Clustering
• Periodic independent selfelection
– Probabilistic
• CSMA MAC used to
advertise
• Nodes select
advertisement with
strongest signal strength
• Dynamic TDMA cycles
t1
t2
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LEACH: Randomized Rotation
• Cluster heads elected every round
– Recent cluster heads disqualified
– Optimal number not guaranteed
• Residual energy not considered
• Assumes energy uniformity
– Impossible with significant network diameters
 P = Desired cluster head
percentage
 r = Current Round
 G = Set of nodes which have not
been cluster heads in 1/P
rounds
P

if n  G

1
1

P
*
(
r
mod
)
T ( n)  
P

0
otherwise
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LEACH: Operation
• Periodic process
• Three phases per round:
– Advertisement
• Election and membership
– Setup
• Schedule creation
– Steady-State
• Data transmission
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Why do we need Aeon LEACH?
•
LEACH protocol for the longer time in the field by increasing its efficiency.
•
LEACH assumes that most of the WSN fields are homogeneous system, but in real-world situation,
it is very difficult to find homogeneous system for a long time or till the network exists.
•
LEACH assumes that all cluster heads pay the same energy cost, which is not possible. The cluster
head in the WSN consumes different amount of energy depending upon the distance between
cluster head to base station and the amount of data it is transmitting.
•
LEACH gives adaptive clustering mechanism which deals very efficiently with energy conservations.
However, LEACH doesn’t take account of residual energy of a node. To address this, a novel
technique as efficient cluster head replacement is proposed.
•
LEACH uses same amplification energy for both kinds of transmissions i.e. cluster head to base
station and CM to CH. To address this, multi amplified power levels are introduced. This is how
much of the energy wasted in cluster head formation process can be saved. Moreover, control
overhead is also limited.
•
LEACH does not determine optimal number of cluster heads in simulation, before implementation.
Round durations never specified or explained in LEACH protocol.
How to replace Cluster head efficiently ?
• LEACH protocol changes the cluster head at every round and once a
cluster head is formed, it will not get another chance for next 1/p
rounds.
• For every round, cluster heads are replaced and whole cluster
formation process is undertaken.
• It is a threshold in cluster head formation for very next round. If
existing cluster has not spent much energy during its tenure and
has more energy than required threshold, it will remain cluster
head for the next round as well.
• This is how, energy wasted in routing packets for new cluster head
and cluster formation can be saved. If cluster head has less energy
than required threshold, it will be replaced according to LEACH
algorithm.
How to decide power of the signal ?
Intra Cluster , Inter Cluster Transmission, Cluster Head
To Base Station Transmission
• Cluster members sense data and Report sensed data to cluster head. The
transmission/ reception between two cluster heads can be termed as inter
cluster transmission while a cluster head transmitting its data straight to
base station lies under the caption of cluster head to base station
transmission.
• Minimum amplification energy required for inter cluster or cluster head to
BS communication and amplification energy required for intra cluster
communication can not be same.
• In LEACH, amplification energy is set same for all kinds of transmissions.
Using low energy level for intra cluster transmissions with respect to
cluster head to BS transmission leads in saving much amount of energy.
• More over, multi power levels also reduce the packet drop ratio, collisions
and/ or interference for other signals
Aeon LEACH Phase-1 Algorithm Details:
Phases of Aeon LEACH
•
•
•
•
•
Advertisement Phase
Cluster Set-Up Phase
Schedule Creation
Data Transmission
Multiple Clusters
Aeon LEACH: Advertisement
• Cluster head self-election
– Status advertised broadcast to nearby nodes
• Non-cluster heads must listen to the medium
– Choose membership based on signal strength
• RSSI
• Eb/N0
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Aeon LEACH: Setup
• Nodes broadcast membership status
– CSMA
• Cluster heads must listen to the medium
• TDMA schedule created
– Dynamic number of time slices
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Aeon LEACH Schedule Creation
• Feedback signals to CH from Nodes
Nodes will join the cluster.
• Cluster Head : TDMA schedule
• Schedule Broadcast
• No change in schedule if Cluster head is same
for the next round.
Aeon LEACH: Data Transmission
•
•
•
•
Nodes sleep until time slice
Cluster heads must listen to each slice
Cluster heads aggregate/compress and transmit once per cycle
Phase continues until the end of the round
–
Time determined a priori
•
Hard Threshold Concept:
•
When a sensed value is greater than the threshold value, data packet will only be transmitted to
receiver. It will minimize the number of transmissions to save the energy of a node. However, it
transmits data always when that threshold is broken; no matter if sensor is sensing the same value
from last many rounds.
•
•
•
Soft Threshold Concept:
When sensed value from node is higher than the previous sensed value, node will transmit the data
to receiver. This will pass messages which have some information in it. This will increase the
network efficiency significantly. This is due to limiting number of transmissions (concept of soft
threshold) along with efficient cluster head replacement mechanism that preserve energy globally
and multi power level for inter and intra cluster communication.
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Aeon LEACH: Interference Avoidance
• TDMA intra-cluster
• CDMA inter-cluster
– Spreading codes
determined randomly
• Non-overlapping
modulation may be NPComplete
– Broadcast during
advertisement phase
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Aeon LEACH Phase-1 Simulation
WSN protocols for Heterogeneous system:
Heterogeneity
• Computational heterogeneity:
• In this type of system, some of the nodes have more energy than
the other normal nodes. The heterogeneous nodes can provide
some benefits such as complex data processing and long term
storage with the use powerful computational resources. We are
going to use this approach in Aeon LEACH Phase 2.
• Link heterogeneity:
• Here, some of the heterogeneous nodes have higher bandwidth
and longer distance network transceiver than the normal nodes. It
can provide more reliable data transmission.
• Energy heterogeneity:
• This system has some of the heterogeneous nodes that are line
powered or their batteries are replaceable.
Characteristics of SEP:
• Being aware of heterogeneity, SEP successfully
outspreads the stable region by assigning weighted
probabilities of cluster-head selection by the initial
energy of initial nodes.
• Due to this outspreaded extended stable region, the
throughput is also increased. The performance of SEP
is extended by distributing the additional energy of the
advanced nodes uniformly to all other nodes in the
field.
• SEP is more robust than LEACH by carefully consuming
this extra energy of the advanced nodes. It yields
longer stability region for higher values of extra energy.
Aeon LEACH Phase 2:
• Our protocol is extension of
SEP. It follows the hybrid
approach i.e. direct
transmission as well as
transmission via cluster head.
Depending on Energy of
nodes, we can divide all the
nodes in advanced nodes with
more energy than normal
nodes.
• For Aeon Phase2 setup, we
will put advance nodes in the
corner for direct transmission
and normal nodes in-between
through cluster head
transmission.
Aeon LEACH Phase 2: Operation
• Direct
communication
• Transmission
through cluster head
Flow Chart for Phase 2:
Aeon LEACH Phase 2: Simulation
Conclusion
• In our work we have briefly describe how cluster based
routing protocol LEACH can be utilized in better way for
homogeneous and heterogeneous environment. Our
simulation shows Aeon Phase 1 gives better throughput of
the system compare to LEACH. We can get better efficiency
by including new CH replacement scheme and different
transmission energy. Moreover, stability of SEP can be
improvised by using two different transmission techniques
direct transmission and CH to sink transmission in
heterogeneous environment implemented in Aeon Phase 2.
• In future, Aeon LEACH can be improvised by adding more
techniques for hierarchal transmissions between CH to
Sink. Again, It will be interesting to apply advanced node
concept with Energy heterogeneity.