Presentation on theme: "Presentation: Energy Efficient Communication Protocol for Wireless Microsensor Networks Wendi Rabiner Heinzelman, Anantha Chandrakasan, and Hari Balakrishnan."— Presentation transcript:
Presentation: Energy Efficient Communication Protocol for Wireless Microsensor Networks Wendi Rabiner Heinzelman, Anantha Chandrakasan, and Hari Balakrishnan Massachusetts Institute of Technology
Underlying Model Hundred to thousands of nodes A fixed basestation A distant basestation (from sensor patch) Basestation is not energy constrained Sensing nodes are heterogeneous Sensing nodes are energy constrained Sensing nodes can aggregate data
50 nano-Joules per bit to operate transmitter and receiver = 0.1 nano-Joules per bit per = Sending = Receiving = Operating the radio, not counting generating the signal, takes power equal to the signal amplifier transmitting 31m. Radio Characteristics
Direct Communication Protocol Givens: k bits, n nodes, r meters between each node Direct communication from furthest node to basestation = r r r … n
Minimum-Energy Multi-Hop Routing (MTE) Assumption: each node sends to nearest neighbor. Direct communication from furthest node to basestation = r r r … n
The Observation Directly sending to the basestation takes less global energy in certain situations Which for the numbers given occurs when exceeds 1000
Pattern of Sensor Node Deaths Direct Routing: nodes further from basestation die first MTE Routing: nodes closer to base station die first Static Clusters: cluster heads die first.
The LEACH Protocol (Summary) Divided into rounds, made of up of turns consisting of: Nodes decide to be a cluster heads this turn. Nodes picks the “closest” cluster head. Cluster heads broadcast transmit schedule. Nodes send data to their cluster head. Cluster head aggregate/compress data and send it to the basestation.
LEACH Comparison Ignoring cluster setup portion of algorithm. 8 times longer for first node to die. 3 times longer for last node to die.
Details of LEACH Deciding to be a cluster head uses a statistic method, where P is the optimal number of clusters (dependent on network parameters (5% in test cases)). Probability of being a cluster head = if haven’t been a cluster head this round 0 otherwise
Details of LEACH (continued) Each cluster head broadcasts a cluster- head-advertisement using CSMA MAC protocol. Nodes receiving the advertisement, choose a cluster head based on signal strength. Nodes (using CSMA protocol) inform chosen cluster head of their choice.
Details of LEACH (continued) Cluster heads generate a TDMA schedule and broadcast to member nodes (may also pick a spreading code for members). Nodes transmit data based on TDMA schedule. Radio’s turned off when not in use.
Details of LEACH (continued) After data has been received, cluster head perform signal processing/compression and send to basestation. After a certain time (determined a prior) a new turn begins. After 1/P turns, a new round begins.
LEACH Animated (P=33%) 1. Decide cluster heads 2. Broadcast advertisement 3. Nodes transmit membership 4. Heads broadcast schedule 5. Nodes transmit data 6. Heads compress data and send to basestation 7. New turn begins goto 1.
Future Work Hierarchical Clustering Cluster size should be variable with distance from basestation? Other thoughts?
Issues (things to think about) Does random picking of cluster heads result in occasional “bad” turns? Their example was hokey, what would the numbers be versus different network layouts? Their MTE routing algorithm always sent to nearest neighbor, how does it compare without this restriction? Is power consumption really “fair” (those far away still seem to consume more power)?