ENERGY EFFICIENT INDOOR LOCALIZATION IN WIRELESS SENSOR NETWORKS Ph.D Student: Sadaf TANVIR Co-Supervisor: Benoît PONSARD Supervisor: Andrzej Duda Insert compass image 17-10-07 Sadaf Tanvir-INPG 2007

Localization in WSNs To achieve Better interpretation of sensed data Inventory monitoring Environment/forest monitoring Smart battlefield To achieve Better interpretation of sensed data Quality of network coverage Geographic Routing Target movement Monitoring Machine survillance Smart hospital Capability of WSNs to self organize Soil moisture monitoring system at Camalie Vineyards California Courtesy: www.timedomain.com 17-10-07 Sadaf Tanvir-INPG 2007

Contents Introduction Preliminary Work Conceived steps of future work Localization using: Beacon approach Beaconless approach Conceived steps of future work 17-10-07 Sadaf Tanvir-INPG 2007

Introduction Types of localization processes: Intrinsic Extrinsic -Endogenous process -Exogenous process Extrinsic more approapriate for WSN Coordinate system Absolute Relative 17-10-07 Sadaf Tanvir-INPG 2007

Related work Localization approaches: Exogenous systems Active badge Active bat RADAR Endogenous systems Cricket GPS based. GPS less GPS-less: Netwide wide coherence(Relative coordinate system) GPS-based: A percentage of networks nodes know their position: Anchor nodes (Absolute coordinate system) 17-10-07 Sadaf Tanvir-INPG 2007

Our focus GPS based localization process involving: Anchor/beacon nodes Unlocalized/free/unknown/blindfolded nodes Unlocalized Nodes Anchor Nodes 17-10-07 Sadaf Tanvir-INPG 2007

Collaborative Process The Process 1D Measurement Position Refinement MAC 2-3D Local Process Collaborative Process 17-10-07 Sadaf Tanvir-INPG 2007

1D Measurement Range free method Range based method 2 Techniques of Distance Measurement: Range free method For achieving coarse grained accuracy 3 methods of distance estimation Sum-Dist DV-hop Euclidean Range based method For fine grained accuracy TOA/TOF TDOA RSSI AOA 17-10-07 Sadaf Tanvir-INPG 2007

Ranging Implementation Ultrasound Radio frequency Many others RF TOF -Provides long range -Good wall penetration -No additional hardware required -Pair wise roundtrip TOF do not require clock synchronization -Ranging accuracy is reported to be between 1-3m(rms) -To pave way for Ultra wide band(UWB) systems (infrared,Laser, Bluetooth, 802.15.4,RFID) Nonradio frquency Communication Optical medium 17-10-07 Sadaf Tanvir-INPG 2007

2-3D Local Process Coversion of 1D distances in 2-3D coordinates If range-free 1D techniques are used Centriod/proximity DV-hop Amporphous Positioning Approximate Point in Triangulation If range based 1D techniques are used Trilateration Maximum Likelihood/Minimum Least Squares Many others Taxonomy of techniques available for position estimation from 1D distance measurement 17-10-07 Sadaf Tanvir-INPG 2007

Collaborative Process Iterative propagation of information across the network through collaboration of neighboring nodes Enables each unlocalized node of the network to calculate its position 5 1 4 3 6 2 17-10-07 Sadaf Tanvir-INPG 2007

Collaborative Process Position Refinement Causes of errors in pair wise TOF Interference, obstruction and multipath fading Clock drift Two kinds of errors Ranging errors Localization errors 1D Measurement 2-3D Local Process Collaborative Process MAC Position Refinement 17-10-07 Sadaf Tanvir-INPG 2007

Indoor Localization Active Research Area More difficult GPS signals not available Signals are affected by walls, furniture, people Reflection, refraction, diffraction and scattering cause interference of RF signals 17-10-07 Sadaf Tanvir-INPG 2007

Collaborative Process Energy Consumption Major source of energy consumption The radio transceiver 1D measurement Position refinement MAC 2-3D local Process Collaborative Process 17-10-07 Sadaf Tanvir-INPG 2007

Our Objectives Design and evaluate indoor WSN localization techniques that are energy efficient To evaluate the Accuracy vs. Energy Consumption trade-off of our suggested approaches 17-10-07 Sadaf Tanvir-INPG 2007

Preliminary work Understanding the localization phenomenon Localization using: Beacon messages Beaconless approach 17-10-07 Sadaf Tanvir-INPG 2007

Beacon Approach(1/2) based on the work of L. De Nardis and M. -G Beacon Approach(1/2) based on the work of L. De Nardis and M.-G. Di Benedetto UN gathers BMs from the three ANs BM from AN1 BM from AN2 BM from AN3 AN1 AN2 AN3 UN AN: Anchor node UN: Unlocalized node ANs receive Query message and reply with a unicast response message (RM) ANs broadcast beacon messages(BM) UN Broadcasts Query message(QM) UN estimates 1D distance between itself and the anchor nodes 17-10-07 Sadaf Tanvir-INPG 2007

Beacon Approach(2/2) The UN only broadcasts QM when there is Pros The UN only broadcasts QM when there is surety of getting 1D measurement through 2 way ranging process Addition of new nodes is easy Cons Constant emission of BM RM emission by LN on its scheduled time highly unsuitable for the 2 way ranging process. 17-10-07 Sadaf Tanvir-INPG 2007

Simulation Results Energy consumption measured as the no. of messages exchanged Node degree(η) =14 17-10-07 Sadaf Tanvir-INPG 2007

Beaconless Approach(1/2) AN3 UN AN: Anchor node UN: Unlocalized node AN2 UN starts the process by broadcasting Query message(QM) AN1 ANs receive Query message and reply with a unicast response message (RM) UN estimates 1D distance between itself and the anchor nodes 17-10-07 Sadaf Tanvir-INPG 2007

Beaconless Approach(2/2) Pros Energy not wasted in broadcasting Beacon messages RM emission by LN: a reaction to the QM making 1D measurement possible Addition of new nodes is easy once the network has converged Cons Redundant QM emission from UNs far from the Anchor group 17-10-07 Sadaf Tanvir-INPG 2007

Simulation Results Node degree(η) =14 17-10-07 Sadaf Tanvir-INPG 2007

Comparison of Beacon vs. Beaconless approach Convergence Latency 17-10-07 Sadaf Tanvir-INPG 2007

Tx/Rx messages 17-10-07 Sadaf Tanvir-INPG 2007

Scope of Current Work Only analyses MAC level message exchange 1D measurement Position Refinement MAC 2-3D local Process Collaborative Process 17-10-07 Sadaf Tanvir-INPG 2007

Drawback of Current Approach Information propagation over a large number of hops Error accumulation and poor accuracy 17-10-07 Sadaf Tanvir-INPG 2007

Collaborative Process Future work Step 1: Study AN placement in the network Its effect on: Accuracy of location estimation Communication cost Convergence latency 1D measurement 2-3D local Process Collaborative Process MAC Position refinement 17-10-07 Sadaf Tanvir-INPG 2007

Future work Step 2: Study and analyse the energy consumption during collaborative process 1D measurement Position Refinement MAC Through the use of Robust least squares 2-3D local Process Collaborative Process 17-10-07 Sadaf Tanvir-INPG 2007

Future work Study comunication cost, convergence latency and accuracy w.r.t AN placement in the network Implement the RLS approach and evaluate it in terms of Accuracy achieved vs. Energy consumed Evaluate our suggested approach on energy efficient MAC protocol designed for WSNs and realistic indoor propagation models Direct my work towards application oriented localization e.g. Localization for geographic routing To evaluate the accuracy vs. Energy trade-off 17-10-07 Sadaf Tanvir-INPG 2007

THANK YOU! Questions Comments Feed back Critique 17-10-07 Sadaf Tanvir-INPG 2007