Leach-Protocol
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This document describes the LEACH (Low-Energy Adaptive Clustering Hierarchy) protocol for wireless microsensor networks. LEACH utilizes randomized rotation of cluster heads to distribute the energy load evenly among the sensors and achieves longer system lifetime. It uses localized coordination and control for data transfers to reduce global network communication. LEACH allows adaptive clustering and uses data aggregation in the clusters to reduce global data transmission and improve system scalability and energy efficiency. Simulation results show that LEACH distributes energy load evenly and outperforms other routing protocols by achieving up to a factor of 4 times increase in system lifetime.
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Leach-Protocol
- 1. An Application-Specific Protocol Architecture for Wireless MicrosensorNetworksbyWendi RabinerHeinzelmanAnathaChandrasakanHariBalakrishnanPresenter: ZhendongLun1
- 3. Background
- 6. Conclusion
- 7. Reference2
- 10. Limited energy
- 13. System lifetime
- 14. Latency
- 15. Quality
- 16. Neighboring nodes may have same data
- 17. End user cares about a higher-level description of events3
- 18. LEACH (Low-Energy Adaptive Clustering Hierarchy)Techniques (to achieve the design goals)Randomized, adaptive, self-configuring cluster formation.
- 19. Localized control of data transfers
- 20. Low energy media access control (MAC)
- 21. Application specific data processing, such as data aggregation and compression. 4
- 22. BackgroundSome application-specific protocols developed for MSNTime division multiple-access(TDMA) MAC protocol for low-energy operation.
- 23. “Power-aware” routing protocols for wireless networks.
- 24. “Minimum transmission energy”(MTE) routing
- 25. Clustering
- 26. Nodes send data to central cluster head
- 27. Cluster head forwards data
- 28. Cluster head has to be high energy node
- 30. LEACH Protocol ArchitectureLEACH in briefRandomized rotation of cluster heads among the sensors
- 31. All non-cluster head nodes transmit data to their cluster head
- 32. CH receives this data and performs signal processing functions on the data and transmits data to the BS6
- 33. 7
- 34. 8
- 35. LEACH Protocol ArchitectureLEACH Step by StepCluster Head Selection
- 38. LEACH-C: BS Cluster Formation9
- 39. Cluster Head Selection AlgorithmsPi(t) is the probability with which node i elects itself to be Cluster Head at the beginning of the round r+1 (which starts at time t) such that expected number of cluster-head nodes for this round is k. k= # of clusters during each round (1) N= # of nodes in the networkEach node will be Cluster Head once in N/k rounds.
- 40. Probability for each node i to be a cluster-head at time t(2)Ci(t) = it determines whether node i has been a cluster head in most recent (r mod(N/k))rounds.10
- 41. Cluster Head Selection Algorithms (cont.)(3) = total no. of nodes eligible to be a cluster-head at time t.This ensures energy at each node to be approx. equal after every N/k rounds.Using (2) and (3), expected #of Cluster Heads per round is,11
- 42. Cluster Formation AlgorithmCluster Heads broadcasts an advertisement message (ADV) using CSMA MAC protocol.
- 43. ADV = node’s ID + distinguishable header.
- 44. Based on the received signal strength of ADV message, each non-Cluster Head node determines its Cluster Head for this round.
- 45. Each non-Cluster Head transmits a join-request message (Join-REQ) back to its chosen Cluster Head using a CSMA MAC protocol.
- 46. Join-REQ = node’s ID + cluster-head ID + header.
- 47. Cluster Head node sets up a TDMA schedule for data transmission coordination within the cluster.
- 48. TDMA Schedule
- 49. Prevents collision among data messages.
- 50. Energy conservation in non cluster-head nodes.12
- 51. Flowchart of the distributed cluster formation algorithm for LEACH13
- 52. Steady State Phase Time line showing LEACH operationTDMA schedule is used to send data from node to cluster head.
- 53. Cluster head aggregates the data received from nodes in the cluster.
- 54. Communication is via direct-sequence spread spectrum (DSSS) and each cluster uses a unique spreading code to reduce inter-cluster interference.Data is sent from the cluster head nodes to the BS using a fixed spreading code and CSMA. 14
- 55. Steady State Phase Time line showing LEACH operationAssumptions
- 56. Nodes are all time synchronized and start the setup phase at same time.
- 57. BS sends out synchronized pulses to the nodes.
- 58. Cluster Head must be awake all the time.
- 59. To reduce inter-cluster interference, each cluster in LEACH communicates using direct-sequence spread spectrum (DSSS).
- 60. Data is sent from the cluster head nodes to the BS using a fixed spreading code and CSMA.15
- 61. Flow chart for steady state phase16
- 62. LEACH-C: BS Cluster FormationUses a central control algorithm to form clustersDuring setup phase each node sends its location and energy level to BS
- 63. BS assigns cluster heads and clusters
- 64. BS broadcasts this information
- 65. The steady-state phase is same as LEACH17
- 66. Analysis and Simulation100 node random test network18
- 67. Analysis and Simulation (cont.)Optimum Number of Clusters19
- 68. LEACH distributes more data per unit energy than MTE
- 69. LEACH-C delivers 40% more data per unit energy than LEACH20
- 70. LEACH and LEACH-C’s nodes lifetime is much longer than MTE’s
- 71. LEACH can deliver 10 times the amount of effective data to the BS for the same number of node deaths21
- 72. ConclusionMicrosensor network protocols must be designed for
- 75. High quality
- 76. LEACH
- 77. Better energy utilization and system lifetime
- 78. Load balancing is achieved
- 79. All nodes die at a time22
- 80. ReferenceHeinzelman Wendi Rabiner, ChandrakasanAnantha, and BalakrishnanHari. An Application-Specific Protocol Architecture for Wireless Microsensor Networks. IEEE Transactions On Wireless Communication, Vol. 1, No. 4, October 200223