“Localization in Underwater Sensor
Networks”
Presented by:
Ola Ibrahim EL naggar

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.

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

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.

Range-based
Schemes
Infrastructurebased
Distributed
Positioning
With Mobile
Beacons
Without
Anchors
Range-free
Schemes
Hop-countbased
Centroid
Area
Localization
Approximate
Point In
Triangle
Signal Processing
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

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