Transcript 7 LBS AUI VF

METIS First Master Training & Seminar
Localization-Based Systems (LBS)
Al Akhawayn University in Ifrane
Professor Driss Kettani
Ahmed Eloufir
email: (D.Kettani/Ah.Eloufir)@aui.ma
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Localization-Based Systems (LBS):
Plan of the Presentation
1.
2.
3.
4.
5.
6.
7.
8.
9.
Introduction
LBS and GIS
Components of LBS
Context of use of LBS
What are LBS used for?
Architectural aspects
Categories of LBS
Overview of most known LBS systems
Applications
The METIS project is managed by the European GNSS Supervisory
Authority through Euro-MED GNSS I project
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METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007
1. Introduction
 It is an information System whose main value is related to the
processing/exploitation of the spatial position of its data… Device
independent…
 LBS allow to define the location of a point situated on the surface of Earth…
 The need of a Projection system… UTM, Lambert Planar, Albers Conic
Equal Area, etc.
 The SADD effect… Shape, Area, Distance, Direction distortion due the
projection system…
 The link between the physical feature on earth and its “spatial coordinates”
is not always accurate…
 The use of the appropriate projection system impacts directly the accuracy
of the LBS added value…
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METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007
1. Introduction
Most Distorted
3D spherical
coordinates are
projected onto the
projection surface
(a map sheet) to
create a flat planar
coordinate system.
Least Distorted
Most Distorted
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METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007
2. LBS and GIS
 LBS allows to locate an object on the earth surface, whereas GIS
allows to describe the location of the object.
 Having a coordinate location is, generally, of little value: i.e. knowing
that object A is located in (-6.85,34) would make a little sence,
however, if we say that object A is located in the intersection of
“Boulevarde de France” and street “Oued Oum Rabii” in Rabat,
Agdal, would definitely make more sence.
 LBS allows mapping in GIS:
 Collect points coordinates (x,y) with LBS...
 Calibrate image map using those points and LBS coordinate system...
 Create features on the new calibrated map...
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METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007
3. Components of an LBS
 Most of the time: LBS = Location/Communication infrastructure +
GIS + user device…
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4. Context of use of an LBS
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METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007
5. What are LBS used for?
 Location: determining a basic position. Example…
 Navigation: getting from one location to another . Example…
 Tracking: monitoring the movement of people and things.
Example…
 Mapping: creating maps of the world. Example…
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LBS
Components
6. General Architecture (1/2)
LBS Components and Information Flow
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METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007
6. General Architecture (2/2)
L
Signal
B
Ground
Stations
Signal
Satellite
Constellation
S
GPS
Receiver
Mobile Phone
(GSM)
Coordinate System
G
I
S
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7. Categories of LBS:
7.1. Satellite-based localization
 Generally, they are composed of:
Space segment: a constellation of satellites…
Control Segment: The monitoring stations continually monitor
satellite positions and provide updated times and ephemeris for
the satellites to keep them in synchronism with standards of time
and position on the Earth…
User Segment: Receivers…
 A receiver obtains signals from the satellites so as to calculate
its coordinates
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7. Categories of LBS:
7.1. Satellite-based localization
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METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007
7. Categories of LBS:
7.1. Satellite-based localization
 If you know you are 10 miles from satellite A in the sky, you could be
anywhere on the surface of a huge, imaginary sphere with a 10-mile
radius.
 If you also know you are 15 miles from satellite B, you can
overlap the first sphere with another, larger sphere. The spheres
intersect in a perfect circle.
 If you know the distance to a third satellite, you get a third sphere,
which intersects with this circle at two points.
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7. Categories of LBS:
7.2. GSM-based localization
GSM Network: System Architecture
GSM Network: Geographical Structure
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METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007
7. Categories of LBS:
7.2. GSM-based localization
 Positioning with GSM:
Cell of Origin (COO)
Timing Advance (TA)
Time of Arrival (TOA)
Time Difference of Arrival (TDOA)
Angle of Arrival (AOA)
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METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007
7.2.1. Positioning with GSM: COO
 The method uses the cell area in which the mobile station is
registered by identifying the cell-ID of serving cell, BTS can be
found.
 The BTS has a fix position and known properties, such as signal
strength
 An area around the BTS can be calculated in which the handset
should be located to receive signals in this cell.
 This method is fairly inaccurate. The area calculated around the BTS
is based on transmitted signal strength and known signal
attenuation, which would give a radius around the BTS.
 This method depends upon the network cell size, which can vary
from 150m in an urban area up to 35,000m in a rural area.
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7.2.2. Positioning with GSM: TA
 A way to improve COO is to enhance the method using the Timing
Advance value, (TA).
 TA is used to synchronize the signals between the MS and the BTS.
 Each increment of the TA value corresponds to a distance of about
550m (e.g. TA value of 0 means the MS is between 0 and 550m away
from the BTS, a value of 5 means between 2750 and 3300m away).
 By using the TA value, in addition to the COO, the circle around the
BTS will be narrowed down to an approximate 550m wide arc.
 The TA value is stored in both the network and the MS, and can be
retrieved at both positions.
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7.2.3. Positioning with GSM: TOA
 TOA works by measuring signals sent from the MS to three or more
BTSs.
 By sending a known signal the BTS can receive the signal and hand
it over to a Location Measurement Unit (LMU).
 The LMU measures the time it took for the signal to travel between
the MS and the BTS, the TOA value.
 These values can be used to calculate a circle around the BTS,
since the propagation time of the radio wave is directly proportional
to its traversed distance. Calculating where the circles from three
different BTSs intersect will give the proximate location of the MS
(Triangulation).
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7.2.4. Positioning with GSM: TDOA
 TDOA is a variation of the TOA, and can be used if the time the
signal was sent isn’t known or not accurate.
 The LMU at the BTS marks the time when the signal arrived from the
MS, d1.
 This value is compared against when the signal arrived to another
BTS, d2.
 The difference between the two arrival times, d1-d2, is called the
TDOA value.
 A curve is calculated along the line where the TDOA value is
constant, a hyperbola.
 By using two pairs of BTSs, at least three BTSs, two hyperbolas can
be calculated and an intersection found where the MS is located.
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METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007
7.2.5. Positioning with GSM: AOA
 If the angle in which the signal from the MS arrives to the BTS can
be measured, a line can be drawn from the BTS using this angle…
 By measuring the angle at two or more different BTSs an
intersection of the lines can be calculated where the MS would be
located…
 An advantage of this method is that only two BTSs are required to
find an intersection…
 The main disadvantage is the need of complex antennas to measure
the angle…
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METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007
7. Categories of LBS:
7.3. Other types of localizations
Wireless signal positioning…
TV signal positioning…
IP address positioning…
Domain name system (DNS) positioning…
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METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007
8. Overview of most known LBS systems:
8.1. Global Positioning System (GPS)
 Name: NavStar Global Positioning System (GPS)
 Owner: US Department of Defense
 Dates:
 Launching :1973
 Operational: 1978
 Cost: 13M$
 Characteristics:
 24 satellites
 6 orbits (55°)
 Altitude: 20180km
 Revolution: 11h58min
 Frequencies:
 1575.42 MHz civilian
 1227.60 MHz military
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METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007
8. Overview of most known LBS systems:
8.2. Galileo
 Name: Galileo
 Owner: ESA (European Space Agency)
 Dates:
 Launching :2006
 Operational: 2008
 Cost: 3.6M€
 Characteristics:
 30 satellites
 3 orbits (56°)
 Altitude: 23222km
 Frequencies:
 1164-1215 MHz
 1215-1300 MHz
 1559-1592 MHz
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METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007
8. Overview of most known LBS systems:
8.3. GLONASS
 Name: Global Navigation Satellite System (GLONASS)
 Owner: USSR
 Dates:
 Launching :1982
 Operational: 1993
 Cost: N/A
 Characteristics:




24 satellites
3 orbits (64.8°)
Altitude: 19130km
Revolution 11h15min40s
 Frequencies:
 1602.94-1614.94 MHz civilian
 12240-1260 MHz military
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METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007
9. Applications:
9.1. e-Tourism
 Remote Tourist Tracking (RTT): The
RTT is a tool that allows tracking,
monitoring and helping tourists
exploring harsh regions.
 It requires tourist vehicles to be
equipped with spatial localization
devices (a GPS receiver) and
connected, thanks to a wireless
communication media (e.g. GSM),
to a Central Tourist Server. The RTT
is based on a tracking system that
localizes in real time groups of
tourists around the region.
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9. Applications:
9.2. e-Transport
E-Transport allows companies to manage their fleet
in an effective/optimized way…
Back office and front office…
E-Transport includes three components:
 A tracking and guidance component…
 An intelligent delivery schedule and
component…
 A driving follow up component…
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METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007
9. Applications:
9.2. e-Transport Architecture
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METIS First Master Training & Seminar, Ifrane (Morocco), 15-16.03.2007
9. Applications:
9.3. Geo-GSM
 Geo-GSM: The objective of the Geo-GSM tool is to provide
proximity information services to GSM users using SMS/MMS
messages and without any specific localization device…
 Typical queries that the Geo-GSM can handle are:
 What is the nearest Café?
 What is the phone numbers of the hotels that are in proximity?
 What is the address of the nearest Pizzeria?
 How far is the train Station?
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9. Applications:
9.3. Geo-GSM Architecture
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Thank You!
http://www.aui.ma/GNSS/metis/
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