EnergyEfficient Communication Protocol for Wireless Microsensor Networks

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Energy-Efficient Communication Protocol for
Wireless Microsensor Networks

• Proceedings of 33rd Hawaii International
  Conference on System Sciences 2000 IEEE

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Outline

• Introduction
• First Order Radio Model
• Energy Analysis of Routing Protocols
• LEACH Algorithm Details
• LEACH Low-Energy Adaptive Clustering Hierarchy
• Conclusions

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Introduction (1/2)

• Based on protocols of direct transmission,
  minimum-transmission-energy, multihop-routing,
  and static clustering may not be optimal for
  sensor networks.
• LEACH, 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.

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Introduction (2/2)

• LEACH is able to perform local computation in
  each cluster to reduce the amount of data that
  must be transmitted to the base station
• This achieves a large reduction in the energy
  dissipation, as computation is much cheaper than
  communication

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First order radio model (1/3)
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First order radio model (2/3)
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First order radio model (3/3)

• To transmit a k-bit message a distance d using
  our radio model, the radio expends
• To receive this message, the radio expends

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Energy Analysis of Routing Protocols (1/7)

• Node A would transmit to node C through node B if
  and only if

B
5
5
A
C
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Energy Analysis of Routing Protocols (2/7)

• The direct communication approach
• In MTE routing

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Energy Analysis of Routing Protocols (3/7)

• Direct communication requires less energy than
  MTE routing if

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Energy Analysis of Routing Protocols (4/7)

• The base station is fixed and located far from
  the sensors.
• All nodes in the network are homogenous and
  energy-constrained

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Energy Analysis of Routing Protocols (5/7)
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Energy Analysis of Routing Protocols (6/7)
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Energy Analysis of Routing Protocols (7/7)
Direct transmission
MTE routing
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LEACH Algorithm Details (1/8)
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LEACH Algorithm Details (2/8)

• Advertisement Phase
• n node number (total 10 nodes)
• P the desired percentage of cluster heads(e.g.,
  P0.2)
• r the current round ( at most 5 rounds)
• G the set of nodes that have not been
  cluster-heads in the last 1/P rounds

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LEACH Algorithm Details e.g. (1/8)
Round 0 Advertisement Phase
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LEACH Algorithm Details e.g. (2/8)
Round 0 Cluster Set-Up Phase
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LEACH Algorithm Details e.g. (3/8)
Round 0 Schedule Creation
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LEACH Algorithm Details e.g. (4/8)
Round 0 Data Transmission
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LEACH Algorithm Details e.g. (5/8)
Round 1
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LEACH Algorithm Details e.g. (6/8)
Round 2
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LEACH Algorithm Details e.g. (7/8)
Round 3
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LEACH Algorithm Details e.g. (8/8)
Round 4
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LEACH Algorithm Details (3/8)

• Advertisement Phase
• Each node that has elected itself a cluster-head
  for the current round broadcasts an advertisement
  message to the rest of the nodes
• Each non-cluster-head node decides the cluster to
  which it will belong based on the received signal
  strength of the advertisement

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LEACH Algorithm Details (4/8)

• Cluster Set-Up Phase
• After each node has decided to which cluster it
  belongs, it must inform the cluster-head node
  that it will be a member of the cluster
• During this phase, all cluster-head nodes must
  keep their receivers on

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LEACH Algorithm Details (5/8)

• Schedule Creation
• Based on the number of nodes in the cluster, the
  cluster-head node creates a TDMA schedule telling
  each node when it can transmit
• The schedule is broadcast back to the nodes in
  the cluster

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LEACH Algorithm Details (6/8)

• Data Transmission
• The cluster-head node must keep its receiver on
  to receive all the data from the nodes in the
  cluster
• When all the data has been received, the cluster
  head node performs signal processing fuctions to
  compress the data into a single signal

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LEACH Algorithm Details (7/8)

• Multiple Clusters
• To reduce interference, each cluster communicates
  using different CDMA codes
• The cluster-head then filters all received energy
  using the given spreading code

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LEACH Algorithm Details (8/8)

• Hierarchical Clustering
• The cluster-head nodes would communicate with
  super-cluster-head nodes and so on until the
  top layer of the hierarchy
• For larger networks, this hierarchy could save a
  tremendous amount of energy

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LEACH Low-Energy Adaptive Clustering Hierarchy
(1/5)

• Normalized total system energy dissipated versus
  the percent of nodes that are cluster-heads

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LEACH Low-Energy Adaptive Clustering Hierarchy
(2/5)

• Total system energy dissipated using direct
  communication, MTE routing and LEACH for the
  100-node random network

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LEACH Low-Energy Adaptive Clustering Hierarchy
(3/5)
Direct communication and LEACH
MTE routing and LEACH
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LEACH Low-Energy Adaptive Clustering Hierarchy
(4/5)

• System lifetime

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LEACH Low-Energy Adaptive Clustering Hierarchy
(5/5)

• Sensor that remain alive (circles) and those that
  are dead (dots) after 1200 rounds

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Conclusions (1/2)

• The key features of LEACH are
• 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

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Conclusions (2/2)

• LEACH is completely distributed, requiring no
  control information from the base station, and
  the nodes do not require knowledge of the global
  network in order for LEACH to operate