cellular positioning

1. 1
Cellular Positioning
Pabitra kumar chhatai
Reg no- xxxxxxxxx
GUIDED BY: Ast.prof Dillip kumar
bhadra
Dept. of : Electronics &
Telecommunication
30.11.2012
Koustuv institute of Technology , BBSR

2. Outline
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Introduction.
Positioning Systems.
Global positioning system(GPS).
Differential global positioning system (DGPS).
Wide Area Augmentation Signal(WAAS).
Method of Measurement.
Time of Arrival(TOA).
Time Differential of Arrival(TDOA).
Signal Strength(SS).
Angle of Arrival(AOA).
Comparison Of 4 methods
Conclusion
Dept of : Electronics & Telecommunication.,KIT,BBSR

3. What is cellular positioning ?
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Determining the position of a Mobile Station
(MS),using
location sensitive parameters .
GNNS(Global Navigation Satellite System)
 A network of satellites that used for positioning
and navigation around the globe.
 US- Global Positioning System(GPS)
 Russian- GLObal NAvigation Satellite
System(GLONASS)
 European-GALILEO System
Dept of : Electronics & Telecommunication.,KIT,BBSR

4. Why we need cellular positioning ?
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To provide location based services like...
 Tracking criminals.
 Providing emergency services .
 Military - defence system .
 Map-making.
 Navigation-car navigation system .
 Mountain climbing .
Dept of : Electronics & Telecommunication.,KIT,BBSR

5. Types of positioning systems.
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Mobile centric systems.
Positioning technology inserted inside the
cell.
Currently there 200 millions of cell phones with
out GPS receiver.
Network centric systems.
Positioning technology resides in the network.
This type of systems are compatible with the
phones currently in use.
Dept of : Electronics & Telecommunication.,KIT,BBSR

6. Positioning of a mobile.
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Dept of : Electronics & Telecommunication.,KIT,BBSR

7. What is GPS ?
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Global positioning system(GPS).
 A network of satellites that continuously
transmit coded information, which makes it
possible to precisely identify locations on earth
by measuring distance from satellite.
 Developed in 1980s by U.S Department of
defence.
 24 satellites approximately 20200 km above
the earth
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Dept of : Electronics & Telecommunication.,KIT,BBSR

8. Differential GPS(DGPS)
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By placing additional GPS receiver(called
reference station)
A technique where a data receiver at a known
location is used to correct the data at an
unknown location.
DGPS corrected solution is significantly more
accurate , typical DGPS accuracy is 1-5
meters.
Dept of : Electronics & Telecommunication.,KIT,BBSR

9. DGPS
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Dept of : Electronics & Telecommunication.,KIT,BBSR

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Wide Area Augmentation
Signal.
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Wide Area Augmentation Signal.
A satellite navigation system designed by the
U.S Federal Aviation Administration(FAA) to
boost the accuracy of GPS satellite navigation
.
Wide Area refers to a network of 25 ground
reference stations cover the U.S and some of
Canada and Mexico.
Each station connected to a master station.
Dept of : Electronics & Telecommunication.,KIT,BBSR

11. WAAS
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12. Accuracy of positioning system
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Range
100 m
GPS
With SA
15 m
GPS
Without SA
3-5 m
DGPS
<3m
Dept of : Electronics & Telecommunication.,KIT,BBSR
Positioning
System
WASS

13. Methods of measurement
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Time Of Arrival(TOA)
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Estimated by distance between transmitter and
receiver.
Transmitted by the MS and received at
multiple BSs.
Requirement:
-Position of satellite
-Timestamp
Dept of : Electronics & Telecommunication.,KIT,BBSR

14. TOA
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15. Location probability figures
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16. TOA
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Specific positioning
Algorithms
Measurements
Estimated position
d1,d2,d3
Xm, Ym
 Where distance between MS and BS =
Propagation time * Propagation velocity.
 Al least 3 BSs are required to find the exact
position of MS.
Dept of : Electronics & Telecommunication.,KIT,BBSR

17. 17
Time Different Of
Arrival(TDOA)
Hyperbolic system.
 Converted to a constant distance difference to
two base stations.
 Intersection of
two hyperbolas.
 Requirement:
-Geographical coordinates.
-Precisely synchronized clocks.
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Dept of : Electronics & Telecommunication.,KIT,BBSR

18. TDOA
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Specific positioning
Algorithms
Measurements
Estimated position
d32,d31
Xm, Ym
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Al least 3 BSs are required to find the exact
position of MS from a couple of TDOAs.
When the TOT of MS is unavailable.
Dept of : Electronics & Telecommunication.,KIT,BBSR

19. TDOA
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20. Signal Strength
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Distributed Receiving System(monitoring
post).
Distributed Transmission System(Sing post.)
Similar to TOA.
Measures signal attenuation.
Path-loss ∆P(dB)=10α.log(f/c)-10βlog(4πd).
Okumura-Hata model (OH).
Long distance model.
Dept of : Electronics & Telecommunication.,KIT,BBSR

21. Signal Strength at diff. distance
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22. Angle Of Arrival(AOA)
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Measuring the direction angles.
Least two antenna array systems
The position of the cell phone is determined by
the intersection of the two bearings of the cell
sites.
Require:
-Two dimensional positioning
-Antennas installation
-Interconnection of antennas
Dept of : Electronics & Telecommunication.,KIT,BBSR

23. AOA
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Dept of : Electronics & Telecommunication.,KIT,BBSR

24. Comparison OF 4 methods
Measurement Type
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Advantages
Disadvantages
Time of Arrival (TOA)
• time measurement
required for
TDMA/CDMA network
operation
• simple computations
• synchronized network
required
receiver must know time
of
transmission
• expensive measurement
Time Difference of
Arrival (TDOA)
•time measurement
required for
TDMA/CDMA network
operation
• receiver does not need
time of
transmission
• synchronized network
required
expensive measurement
• complex calculations
Signal Strength
• low cost measurements
•low accuracy in large
cells
• simple computations
•low accuracy in large
cells
Angle of Arrival (AOA)
Dept of : Electronics•simple computations
& Telecommunication.,KIT,BBSR
• specialized antennae
• low accuracy in large

25. Conclusion
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We have described about accurate
positioning of mobile telephones, which can be
used for several applications.
 The important considerations to be undertaken
while selecting a location based technology
are location accuracy , implementation cost,
reliability, increasing functionality.
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Dept of : Electronics & Telecommunication.,KIT,BBSR

26. 26
Questions ?
“Thank YOU”
Dept of : Electronics & Telecommunication.,KIT,BBSR