1. Localization in Wireless Sensor Networks
Poorya Ghafoorpoor Yazdi
Mohammad Zerrat Talab
Masoud Toughian
Maziar Movahedi

2. Outlines Definition about sensor node
Comparison of WSN with Ad Hoc Network
General Application of the wireless sensor networks
Manufacturing Application of WSN
Definition about Localization of WSN
Specific application of localization in manufacturing

3. Outline Definition about wireless sensors Wireless Sensor Networks
Application of WSN
Application of WSN in Manufacturing
Localization – What? Why?
Classification of Localization Algorithms
Examples of Localization Techniques

4. Energy Harvesting System
Node Hardware
1Kbps - 1Mbps,
3-100 Meters,
Lossy Transmissions
128KB-1MB
Limited Storage
Transceiver
8-bit, 10 MHz
Slow Computations
Memory
Embedded
Processor
Sensors
Battery
66% of Total Cost
Requires Supervision
Limited Lifetime
Energy Harvesting System

5. Wireless sensor network VS Ad Hoc Network
Wireless Sensor Networks are networks that consists of sensors which are distributed in an ad hoc manner.
These sensors work with each other to sense some physical phenomenon and then the information gathered is processed to get relevant results.
Wireless sensor networks consists of protocols and algorithms with self-organizing capabilities.

6. Wireless sensor network VS Ad Hoc Network
Wireless sensor networks mainly use broadcast communication while ad hoc networks use point-to-point communication.
Unlike ad hoc networks wireless sensor networks are limited by sensors limited power, energy and computational capability.
Sensor nodes may not have global ID because of the large amount of overhead and large number of sensors.

7. Fields of application of wireless sensor networks

8. Applications of sensor networks
Military applications:
Monitoring friendly forces, equipment and ammunition
Exploration of opposing forces and terrain
Battlefield surveillance
Battle damage assessment
Nuclear, biological and chemical attack detection

9. Applications of sensor networks
Health applications:
Tele-monitoring of human physiological data
Tracking and monitoring patients and doctors inside a hospital
Drug administration in hospitals

10. Example of Products Applicable for Health care
Pulse Oximeter
Glucose Meter
Electrocardiogram (ECG)
Social Alarm Devices

11. Smart Buildings
Sensors and sensor networks are used in multiple smart building applications:
Heating, ventilation, and air conditioning systems
Lightning 
Air quality and window control
Systems switching off devices 
Standard household applications (e.g. televisions, washing machines)
Security and safety (access control)

12. Example of Smart buildings
The headquarters of the New York Times is an example of how different smart building technologies can be combined to reduce energy consumption and to increase user comfort. Overall, the building consumes 30 % less energy than traditional office skyscrapers.

13. Environmental Monitoring
This sensor measures light, temperature, and humidity, and can be equipped to do soil- moisture measurements.
The system takes measurements every second and transmits over 40 meters.(about 3cm diameter)
It was developed for planetary monitoring by the Jet Propulsion Laboratory.

14. Some Interesting Applications
MIT d'Arbeloff Lab – The ring sensor
Monitors the physiological status of the wearer and transmits the information to the medical professional over the Internet
Oak Ridge National Laboratory
Nose-on-a-chip is a MEMS-based sensor
It can detect 400 species of gases and transmit a signal indicating the level to a central control station

15. iBadge - UCLA Investigate behavior of children/patient Features:
Speech recording / replaying
Position detection
Direction detection / estimation(compass)
Weather data: Temperature, Humidity, Pressure, Light

16. Wireless Sensor Networks Applications In manufacturing
WSNs can be used advantageously for rare event detection or periodic data collection for manufacturing applications. In rare event detection, sensors are used to detect and classify rare and random events, such as alarm and fault detection notifications due to important changes in machine, process, plant security or operator actions. On the other hand, periodic data collection is required for operations such as tracking of the material flows, health monitoring of equipment/process. Such monitoring and control applications reduce the labor cost and human errors.

19. End-User View of Manufacturing WSN
Likes
Mobility
Compactness
Flexibility
Low cost
Capability to monitor rotating equipment
Short range (security)
Ease of installation
High reliability
Impetus to enhance electronics support
Dislikes
Change to status quo
Complexity
High cost for coverage in large plants
Security issues
Portability issues (power)
Unproven reliability
Too risky for process control
Lack of experience in troubleshooting (staff)
Restricted infrastructure flexibility once implemented
Lack of analysis tools

20. Manufacturing Application
Inventory Tracking
In-Process Parts Tracking
Customer Tracking
Plant Equipment Maintenance and Monitoring

21. Example of Manufacturing Applications

22. Localization in Wireless Sensor Networks
What?
To determine the physical coordinates of a group of sensor nodes in a wireless sensor network (WSN)
Due to application context, use of GPS is unrealistic, therefore, sensors need to self-organize a coordinate system
Why?
To report data that is geographically meaningful
Services such as routing rely on location information; geographic routing protocols; context-based routing protocols, location-aware services
Low cost of nodes allows massive scale & highly parallel computation
Each node has limited power, limited reliability, and only local communication with neighbors

23. Localization in Wireless Sensor Networks
In general, almost all the sensor network localization algorithms share three main phases
DISTANCE ESTIMATION
POSITION COMPUTATION
LOCALIZATION ALGHORITHM

24. Obtain a Vague Position
End
Start
Exist an Unknown Node which has at least three reference node in its coverage area
End
Select an Unknown Node
Unknown Nod Selection
Obtain a Vague Position
Select Reference Node
Drive local Position for reference Node
Distance Estimation
Estimate the Distance to the Reference Node
Any Selected Reference Node Without Estimated Distance
Calculate the Position of the Selected Unknown Node
Position Computation

25. Localization in Wireless Sensor Networks
The distance estimation phase involves measurement techniques to estimate the relative distance between the nodes.
The Position computation consists of algorithms to calculate the coordinates of the unknown node with respect to the known anchor nodes or other neighboring nodes.
The localization algorithm, in general, determines how the information concerning distances and positions, is manipulated in order to allow most or all of the nodes of a WSN to estimate their position. Optimally the localization algorithm may involve algorithms to reduce the errors and refine the node positions.

26. Distance Estimation
There are four common methods for measuring in distance estimation technique:
ANGLE OF ARRIVAL (AOA)
TIME OF ARRIVAL (TOA)
TIME DIFFERENT OF ARRIVAL (TDOA)
THE RECEIVED SIGNAL STRENGH INDICATOR (RSSI)

27. Distance Estimation
ANGLE OF ARRIVAL method allows each sensor to evaluate the relative angles between received radio signals
TIME OF ARRIVAL method tries to estimate distances between two nodes using time based measures
TIME DIFFERENT OF ARRIVAL is a method for determining the distance between a mobile station and nearby synchronized base station
THE RECEIVED SIGNAL STRENGTH INDICATOR techniques are used to translate signal strength into distance.

28. Position Computation
The common methods for position computation techniques are:
LATERATION
ANGULATION

29. Position Computation
LATERATION techniques based on the precise measurements to three non collinear anchors. Lateration with more than three anchors called multilateration.
ANGULATION or triangulation is based on information about angles instead of distance.

30. Classifications of Localization Methods
According to the ways of Sensors implementation, we classify the current wireless sensor network localization algorithms into several categories such as:
Centralized vs Distributed
Anchor-free vs Anchor-based
Range-free vs Range-based
Mobile vs Stationary

31. Centralized vs Distributed
All computation is done in a central server
Distributed
Computation is distributed among the nodes

32. Anchor-Free vs Anchor-Based
Anchor Nodes:
Nodes that know their coordinates a priori
By use of GPS or manual placement
For 2D three and 3D four anchor nodes are needed
Anchor-free
Relative coordinates
Anchor-based
Use anchor nodes to calculate global coordinates
Disadvantages of anchor nodes:
GPS receivers are expensive.
cannot typically be used indoors
GPS receivers also consume significant battery
Alternative to GPS is preprogramming nodes with their locations, which can be impractical
(for instance, when deploying 10,000 nodes with 500 beacons) or even impossible
(for instance, when deploying nodes from an aircraft).

33. Range-Free vs Range-Based
Local Techniques
Hop-Counting Techniques
Range-Based
Received Signal Strength Indicator (RSSI)
Attenuation
RF signal
Time of Arrival (ToA)
time of flight
Time Difference of Arrival (TDoA)
requires time synchronization
electromagnetic (light, RF, microwave)
sound (acoustic, ultrasound)
Angle of Arrival (AoA)
Range-free:
Only use connectivity information
Not very accurate
Range-based:
require extra hardware therefore have a higher cost,
Much more accurate

34. Proposed Method
Range Based Centralized Localization using Neural Networks

36. Training

39. Experiment

41. (1,1)
(4,3)
(2,7)
(5,5)
(7.5,7.3)
(9,5)
Anchor node 1
-47
-66
-73
-72
-70
-69
Anchor Node 2
-74
-75
-63
Anchor Node 3
-71
Anchor Node 4