Energy-Efficient Communication Protocol for Wireless Microsensor networksW. R. Heinzelman, A. Chandrakasan, and H. BalakrishnanPresented by Dezhen Song, EE 228AContents• Introduction• First order radio model• Energy analysis of routing protocols• LEACH: Low-Energy Adaptive Clustering Hierarchy• LEACH Algorithm details• ConclusionIntroduction• Characteristic of the sensor network– Base station is fixed and far way from the sensors– Homogeneous nodes and energy constrained Sensors Base stationEnergy model• Energy for run circuitry• Energy for radio transmission• Energy for sending k bits over distance d• Energy for receiving k bitsnJ/bit50=elecE2pJ/bit/m100=ampε2),( kdkEdkEampelecTxε+=kEdkEelecRx=),(Energy analysis of routing protocols• Direct communicationBase stationSensorsEnergy analysis of routing protocols• Minimum transmission energy2),( kdkEdkEampelecTxε+=Base stationSensorsEnergy analysis of routing protocols• Minimum transmission energy– Save on transmission energy– Waste on circuitry energy used for receiving– Direct communication requires less energy if22nrEampelec≥εEnergy analysis of routing protocols• A 100 node caseBase station(0, -100)Energy analysis of routing protocols• Energy dissipated for the 100-node caseEnergy analysis of routing protocols• System lifeEnergy analysis of routing protocols• Remaining nodes after 180 roundsDirect Communication MTELEACH: Low-Energy Adaptive Clustering Hierarchyt1t1+dLEACH: Low-Energy Adaptive Clustering Hierarchy• Number of clustersHow do we get the optimal number of clusters in real system?LEACH: Low-Energy Adaptive Clustering Hierarchy• Energy consumption comparisonLEACH: Low-Energy Adaptive Clustering Hierarchy• System lifetime comparisonSynchronized die out Vs Gradual die out?LEACH: Low-Energy Adaptive Clustering Hierarchy• Remaining nodes after 1200 roundsNot complete even distributionLEACH Algorithm Details• How to generate cluster head?– P: the desired percentage of cluster heads– r : the current round– G: set of nodes that have not been cluster-heads in the last 1/P rounds∈−=Otherwise 0 If )1mod(1)(GnprPPnTResults• Reduce communication energy by 8X• The first node death in LEACH occurs over 8X later the counterpart in direct transmission, MTE, and static routing. The last node death occurs 3X times later than the last node death in the other
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