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Energy Conservation in wireless sensor networks. Kshitij Desai, Mayuresh Randive , Animesh Nandanwar. Basic Design. Sensor Network Architecture. Sink. Sensor Network. Internet. Architecture of a Sensor Node. Ref: Energy Conservation in Wireless Sensor Networks – a Survey. Observations.
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Energy Conservation in wireless sensor networks Kshitij Desai, MayureshRandive, AnimeshNandanwar
Basic Design • Sensor Network Architecture Sink Sensor Network Internet
Architecture of a Sensor Node • Ref: Energy Conservation in Wireless Sensor Networks – a Survey
Observations • Communication Sub-system consumes more energy than computation sub-system • Energy to transmit one bit = Energy for execution 1000 . instructions • Radio component requires same order of energy for reception, transmission and idle states • Sensing sub-system might also require significant amount of energy based on the type of sensor node.
Three Main enabling Techniques • Duty-cycling • Data-Driven approaches • Mobility
Duty-cycling • Topology Control • Power Management • Sleep/Wake Protocols • On-demand, scheduled rendezvous and Async • MAC Protocols with low Duty-cycle • TDMA, Contention-based and hybrid
Data-driven approaches • Data reduction • In-Network Processing • Data-Compression • Data-prediction • Stochastic, Time-series Forecasting and algorithmic approaches • Energy-efficient data acquisition • Adaptive Sampling • Hierarchical Sampling • Model-Driven active sampling
Mobility-based approaches • Mobile-sink • Mobile-relay
ATPC: Adaptive Transmission Power Control for WirelessSensor Networks
Main Points • What is this paper about? • Power saving for wireless communication • Paper style? • Empirical study + a little theory work • What is the contribution? • Study of spatial-temporal impact on communication • Mechanism to adaptively achieve an optimal transmission power consumption
Motivation TP1 TP2 TP2
Motivation T2 TP1 T1 TP2 T2 TP1 The minimum transmission power level to save energy and maintain specified link quality
Design Goals • Achieve energy efficiency • The minimum transmission power • Maintain Link Quality • Reliable links • In runtime systems, dynamic environments • Spatial impact • Temporal impact
Roadmap Data Analysis Empirical Observation PART 1 Algorithm Design PART 2 Algorithm Evaluation
Part 1-Transmission Power vs. Link Quality • Link Quality Metrics • RSSI (Received Signal Strength Indication), LQI (Link Quality Indication), and PRR (Packet Reception Ratio) • Transmission Power Level Index (3~31) • Experiments on Spatial Impact • 5 pairs of motes, 3 environments • 100 packets at each transmission power level • RSSI/LQI/PRR measured at different distances
Part 1- Investigation of Spatial Impact (a) RSSI measured on a grass field (b) RSSI measured in a corridor • Different shapes at the same distance in different environments • Different degree of variation in different environments • Approximately linear (c) RSSI measured in a parking lot
Investigation of Temporal Impact • Experiment on Temporal Impact • In brushwood where human activity is rare, over 72 hours • 9 MicaZ motes in a line, 3 feet apart • A group of 20 packets at each power level every hour (a) RSSI measured every 8-hour (b) RSSI measured every hour • 1. Vary gradually but noticeably over time • 2. Approximately parallel
Part 1- Link Quality Threshold (a) RSSI Threshold on a grass field (b) LQI Threshold on a grass field Binary link quality thresholds Slight different in different environments
Part 2- Model Design of ATPC • Use a linear model to approximate a non-linear correlation • rssi(tp) = a · tp +b • Least-square approximation • Dynamic model • a and b vary from time to time
Part 2- ATPC Overview 25 8 Initialization Phase: build models from linear approximation Runtime Tuning Phase: pairwise closed loop control
Part 2 – Closed Loop Control Start here RSSI, LQI and PRR
Part 2- Experiment Setup • Current transmission power control algorithms • A node-level non-uniform solution (Non-uniform) • Network-level uniform solutions • Max transmission power level (Max) • The minimum transmission power level over nodes in a network that allows them to reach their neighbors (Uniform) • A 72-hour continuous experiment with MicaZ • A spanning tree of 43 nodes, 24 leaf nodes • Leaf nodes send 32 packets to the base every hour
Part 2- Experimental Setup (a) Weather Conditions over 72 Hours (b) Spanning Tree Topology (c) Experimental Site
Part 2- Packet Reception Ratio • E2E packet reception ratio • Max ~ 100% • ATPC ~ 98.3% • Uniform ~ 98.3% • Non-Uniform ~ 58.8% (b) PRR at a chosen link ATPC ~ constantly 100% Static transmission power ~ vary from 0% to 100%
Part 2- Transmission Energy Consumption Relative energy consumption Max ~ 100% ATPC ~ 58.3% (1% control overhead) Uniform ~ 68.6% Non-Uniform ~ 43.2%
Conclusions and Future Work • Benefits of ATPC lie in three core aspects: • ATPC maintains above 98% E2E PRR over time • ATPC achieves significant energy savings • 53.6% of the transmission energy of Max • 78.8% of the transmission energy of Uniform • ATPC accurately adjusts the transmission power • Adapting to spatial and temporal factors • Towards reliable and energy-efficient routing • Spatial reuse for concurrent transmissions
Questions? Thank you very much!