Report

788.11J presentation “Localization in Underwater Sensor Networks” Presented by: Ola Ibrahim EL naggar introduction Deployment of low cost wireless sensors is proving to be a promising technique for several applications. Challenge in large scale wireless networks: 1- the limited processing capability 2- power constraints on each sensor. 1. Underwater application Underwater Environmental Observation For Scientific Exploration Oil Drilling Commercial Exploitation Coastline Protection Military Applications 1.1 Oil Drilling to 1- vessels are generally huge and are anchored the seabed with multiple anchors. 2- smart sensors can monitor environmental and system parameter can be deployed on the seabed. 3- work with Remotely Operated Vehicles (ROV). 4- controlled from - ship -Autonomous Underwater Vehicles (AUV) 1.1 Oil Drilling 5- The sensors, anchors and ROVs/AUVs collect information from the seabed and feed the data to the vessel. 6- sensors and anchor can measure parameters like foundation strength and mooring tensions, and ideally provide accurate position references to the AUVs. 7- They survey the deep sea environment e “The location of the sensors, anchors and the AUVs need”. 1.1 Oil Drilling 1.2 Challenges location of the sensors This problem is especially challenging for deep water applications. Localization underwater is challenging as Radio Frequency (RF) waves are heavily attenuated under water and hence, employing technology like GPS is not feasible. 2. UWSNs Localization Schemes Range-based Schemes Range-free Schemes Infrastructurebased Hop-countbased Distributed Positioning Centroid With Mobile Beacons Area Localization Without Anchors Approximate Point In Triangle Signal Processing Schemes 2.1 Range-based Schemes Estimate distance to other nodes. Time of Arrival (ToA) Time Difference of Arrival (TDoA) Angle of Arrival (AoA) Received Signal Strength Indicator(RSSI). 2.1.1 Infrastructure-based schemes Anchor Nodes on Seabed Pre-determined Locations Surface Buoys as Anchor Nodes GPS-equipped Distance Estimation ToA 2.1.2 Distributed Positioning Schemes Limited Communication Only With One-hop Neighbor Three Phases 1-Distance Estimation Phase 2-Position Estimation Phase System of Linear Equations 3-Refinement Phase 2.1.3 Schemes that use Mobile Beacons/Anchors No Fixed Anchors Mobile Anchors Traverse The Network Send Beacon Packets Location Coordinates of Anchor Node Localization RSSI 2.1.4 Schemes without Anchor/Reference Points No Anchors Central Server Model: Series of Equations Sophisticated Optimization Techniques 2.2 Range-free Schemes 1-Do not use range or bearing information: -No ToA, TDoA, or AoA 2-Coarse Location Estimation 2.2.1 Hopcount based Schemes Distance Vector Exchange Exchange updates with neighbors. Anchor estimates average one-hop distance. Performs Well: Uniform and Dense Node Distribution. 2.2.2 Centroid Scheme Dense Rectangular Mesh of Anchors Anchor Locations in Beacon Signals Location is anchor nodes centroid. Hard to Implement Underwater 2.2.3 Area-based Localization Has two examples: 2.2.3.1 Area Localization Scheme (ALS) 2.2.3.2 Approximate Point In Triangle (APIT) 2.2.3.1 Area Localization Scheme (ALS) 2.2.3.2 Approximate Point In Triangle (APIT) Point-In-Triangle Test Only In Air. Approximate Point-In-Triangle Test Use RSSI from three anchors. Try all combinations. Central Server 2.3 Signal Processing/Probabilistic Schemes Relies on signal characteristics. Not Signal Timing Not Signal Strength Signature Database Hard to Generate Schemes Comparison Thank you