Tracking and positioning of mobile systems in telecommunication networks

Tracking and posiTioning of a mobile
By: 1) S.Shravan Kumar,
E.C.E, 2nd Year,
R.No.11681A0496,
Christu Jyothi Engineering College,
Jangaon.

Introduction:
 Mobile positioning technology has become
an important area of research, for emergency as
well as for commercial services. Mobile
positioning in cellular networks will provide
several services such as, locating stolen mobiles,
emergency calls, different billing tariffs
depending on where the call is originated, and
methods to predict the user movement inside a
region

Introduction (contd.)
 I present a simple method for
mobile telephone tracking and positioning
with high accuracy. Which presents the
location of a mobile telephone by drawing
a plurality of circles with the radii being
the distances between a mobile telephone
and a several base stations (it will be
found using Time Of Arrival (TOA)) and the
base stations at their centers, and using
location tracking curves connecting the
intersection points between each circle
pair.

Need For Mobile Tracking:
Recent demands from new applications require positioning
capabilities of mobile telephones or other devices. The ability to obtain
the geo-location of the Mobile Telephone (MT) in the cellular system
allows the network operators to facilitate new services to the mobile
users The positioning of the mobile user could provide services like:
Emergency service for subscriber safety.
Location sensitive billing.
Cellular Fraud detection.
Intelligent transport system services.
Efficient and effective network performance and management.

Existing Technologies & Constraints
NETWORK ASSISTED GLOBAL POSITIONING SYSTEM (GPS)
A mobile telephone can be located by a mobile telephone itself or
through a mobile telecommunication network. To locate the mobile
telephone by itself, the mobile telephone is provided with a GPS receiver to
calculate its location in latitude and longitude coordinates based on the
location information received from a satellite through the GPS receiver.
It increases the price and the size of the
mobile telephone.
The load on the mobile telephone is increased.
Power consumption is high.

NETWORK BASED MOBILE POSITIONING
In the case that the mobile telephone network locates the mobile
telephone, at least three base stations (BSs) receive a signal from the
mobile telephone; calculate the distances between the BSs and the mobile
telephone using the arrival time of the signals at the BSs, then determine
the location of the mobile telephone using the trigonometry. This location
service is provided generally by a location data processor included in a base
station controller (BSC).

TIME OF ARRIVAL (TOA)
METHOD :
The TOA method calculates the
distance of a mobile telephone and a BS
based on the TOA of a signal transmitted
from the mobile telephone at the BS. It is
assumed that the mobile telephone is
located at the intersection point of three
circles having the radius of the distances
between the BSs and the mobile
telephone.

TIME DIFFERENCE OF ARRIVAL
(TDOA) METHOD :
The TDOA method assumes that
the TDOAs of a signal transmitted from
the mobile telephone at the three BSs
define a set of points on a hyperbola, and
the mobile telephone is located at the
intersection point of at least three
hyperbolas.
Figure 2: Illustrates a typical TDOA method
for locating a mobile telephone.

Location Tracking Curve Method
When a location service is requested about a specific mobile telephone
by a user or a network, the location data processor draws two circles C1 and
C2 with their respective centers set at BSs T1 and T2 based on the TOAs of a
signal transmitted from the
corresponding mobile telephone M1 or M2
to the two BSs T1 and T2
located near the mobile
telephone M1 or M2.
The two circles C1 and C2
define a common chord L1
Figure: Illustrates a Location Tracking Curve
Method.

Figure: Illustrates determination of
location Tracking Curve
DETERMINATION OF
LOCATION TRACKING CURVE METHOD :
The two curves TR1 and TR2 have
their middle points intersecting the line ST,
which connects the positions of the two BSs
T1 and T2 and the parts of two circles C1 and
C2 drawn to connect the two intersection
points P1 and P2.
This method prevents the location error
caused by the multi-path fading or the NLOS
path characteristics.

REFERENCE CIRCLE SELECTION :
The variances of the TOAs of a signal which arrives at the two BSs T1
and T2 from different paths are
used to find the curve on which
the actual location of the mobile
telephone is determined.
Figure: Illustrates positioning of mobile telephone by the Location Tracking Curve Method

REFERENCE CIRCLE SELECTION (contd.)
After the location of the mobile telephone, that is, the
intersection points among the curves are obtained, the location data
processor represents the intersection points in the latitude and the
longitude coordinates and transmits the position coordinates to the
network (BS/BSC/MSC) and the mobile telephone.

Advantages :
•Used to trace a missing mobile or a theft mobile.
•Used in case of emergency services.
•Used to trace a thief.
•To predict the user movements inside a region.
•Cellular fraud detection.
•Marketing purpose.
•Efficient & effective network performances

Conclusion :
This proposal is advantageous in that the location of a mobile
telephone can be accurately tracked even in the multi-path fading and the
NLOS environment, by using more accurate tracking curves connecting the
intersection points among circles with the radii being the distances between
corresponding BSs and the mobile telephone in a cellular mobile
communication system.
I 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.

Tracking and positioning of mobile systems in telecommunication networks

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Tracking and positioning of mobile systems in telecommunication networks