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 algorithms2) 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.

5

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

• k = Packet size• d = Distance

kEkE

dkkEdkE

elecRx

ampelecTx

*)(

)**()*(),( 2

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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

8

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 self-

election– 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

otherwise 0

G n if )

1mod(*1)(

PrP

P

nT

P = Desired cluster head percentage

r = Current Round G = Set of nodes which have not

been cluster heads in 1/P rounds

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LEACH: Operation

• Periodic process• Three phases per round:

– Advertisement• Election and membership

– Setup• Schedule creation

– Steady-State• Data transmission

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

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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

Aeon LEACH Schedule Creation

• Feedback signals to CH from NodesNodes will join the cluster.

• Cluster Head : TDMA schedule• Schedule Broadcast• No change in schedule if Cluster head is same

for the next round.

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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 NP-Complete

– Broadcast during advertisement phase

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.