Leach protocol

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Leach protocol

  1. 1. LEACH protocol for WIRELESS SENSOR NETWORK CALCUTTA INSTITUTE OF ENGINEERING AND MANAGEMENT 24/1A, CHANDI GHOSH ROAD, KOLKATA-700040 2012-2013 Presented by: RAMESH VERMA ANIL KUMAR PRAVIND KUMAR C.S.E.4th Year
  2. 2. Overview-LowEnergyAdaptiveClusteringHierarchy (LEACH)  Introduction to leach protocol  Two phases of leach  Set-up phase/ thresold algorithm  Set-up phase/advertisement  Set-up to steady state phase  Weakness in leach  DECSA(Distance Energy Cluster Structure Algorithm )  Initialization stage  Stable working stage  comparision
  3. 3. IntroductiontoLEACHprotocol  Falls under hierarchical networks  Self-organizing, adaptive clustering protocol that uses randomization to distribute energy load evenly  Dense network of sensor nodes grouped into clusters.  All nodes are assumed to be homogenous + energy constrained.  Base station is fixed + away from sensors.  Cluster member elect cluster head to avoid excessive energy consumption.  Incorporates data aggregation.
  4. 4. LEACH two phases  It has two phases  The set-up phase and the steady- state phase  The set-up phase where cluster heads are chosen  The steady state phase the cluster head is maintained where data is transmitted between nodes
  5. 5. Set-up phase/ Thresold algorithm  Cluster-heads can be chosen stochastically (randomly based) on this algorithm: T(n) =P/1-P*(r mod/p) if n€G 0 , otherwise Where n is a random no. between 0 and 1 and P is cluster head probability and G is the set of nodes that were not cluster head in the last round.  If n <T(n), then that node becomes a cluster head  The algorithm is designed so that each node becomes a cluster-head at least once
  6. 6. Algorithm - Setup Phase | Advertisement  Each node that elected itself a cluster-head for current round broadcasts advertisement message to rest of nodes  All cluster-heads transmit advertisement using same transmit energy  Non-cluster-head nodes must keep receivers on during this phase to hear advertisements  now they decide which cluster to belong to for this round by choosing cluster-head that requires minimum communication energy  In case of ties, random cluster-head chosen
  7. 7. Algorithm - Setup to Steady Phase  After node picks cluster, must inform cluster- head  Cluster-head now knows number of members  cluster-head then creates a TDMA schedule telling each node when it can transmit  allows radio components of each non-cluster- head node to be turned off during its transmit time, thus minimizing energy dissipated in individual sensors  cluster-head now has all data from the nodes in its cluster, aggregates data & transmits to base
  8. 8. Weakness in LEACH LEACH assumes that  all nodes can communicate with each other and are able to reach the sink (therefore, it is only suitable for small size networks)  all nodes have data to send and so assign a time slot for a node even though some nodes might not have data to transmit.  all nearby nodes have correlated data which is not always true  all nodes are continuously listening ( this is not realistic in a random distribution of the sensor nodes, for example, where cluster-heads would be located at the edge of the network),
  9. 9. DECSA (Distance Energy Cluster Structure Algorithm)  DECSA is improvement over LEACH.  It considers both the distance and residual energy information of nodes.  Three level hierarchy structure of DECSA consists of BS(Base Station), BCH(Base Station Cluster Head), CH( ordinary Cluster head), SN(sensor nodes)
  10. 10. Initialization Stage  The process of cluster head select consists of following 2 parts: election of ordinary cluster head node (CH) and election of Base Station Cluster head (BCH)  First round cluster head is called false-cluster-head  All nodes compare their k(i) with the false cluster head.  If k(i) < false cluster head’s k(i), then false cluster head becomes CH otherwise the node. k(i)=En(i)/do(i) k(i)=thresold of elected CH En(i)=residual energy of node i do(i)=average distance of node I from all other nodes in the network
  11. 11. Initialization Stage Selection of BCH 1.TBCH of all CH is calculated and compared with predefinedTBCH0 2. CH whoseTBCH are larger than the predefined thresholdTBCH0 becomes the base-station cluster- head( BCH). TBCH(i)=(En(i)/Eo)+(En(i)/d(i)) En(i)=current residual energy of node I Eo is the initial energy of node in the network d(i)= distance between node I and the base station
  12. 12. Stable working Stage  base station broadcasts the message to the entire network forming a communication path.  Common nodes (SN) in the cluster will transmit data packet to their closest cluster-head  luster-head will collect and fusion those data and transmit them to the base-station cluster- head, rather than transmit them to the base station directly  then, base-station-cluster-head will communicate with the base station
  13. 13. Comparison  DECSA prolongs 31% of the lifetime, reduces 40% of the energy consumption and has a better performance than the original LEACH protocol.  . Residual energy relationship of nodes between DECSA and LEACH
  14. 14. Conclusion  DECSA considering both the distance and residual energy of nodes  It improved the process of cluster head election and the process of data transmission of network  Reduces the adverse effect on the energy consumption of the cluster head  prolongs 31% of the lifetime, reduces 40% of the energy consumption.
  15. 15. Bibiliography  “Low Energy Adaptive Clustering Hierarchy with Deterministic Cluster-Head Selection”; M.J.Handy, M. Haas, D.Timmermann; 2002; http://www.vs.inf.ethz.ch/publ/se/IEEE_MWCN2 002.pdf  “Probabilistic Modeling of Leach Protocol and Computing Sensor Energy Consumption Rate in Sensor Networks”; Song, Dezhen; February 22,2005; http://www.cs.tamu.edu/academics/tr/tamu-cstr- 2005-2-2

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