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.
1. An Application-Specific Protocol Architecture for Wireless MicrosensorNetworksbyWendi RabinerHeinzelmanAnathaChandrasakanHariBalakrishnanPresenter: ZhendongLun1
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
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
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