PRESENTED BY :
ABINASH MOHAPATRA

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SEMINAR ON TRACKING & POSITIONING IN MOBILE COMMUNICATION
WHAT IS MOBILE TRACKING
It tracks the current position of a mobile phone even on the move. To locate the phone, it must emit at least the roaming signal to contact the next nearby antenna tower, but the process does not require an active call.
What is Mobile positioning
It is a location based service that discloses the actual coordinates of a mobile phone bearer, is a technology used by telecommunication companies to approximate where a mobile phone, and thereby also its user (bearer), temporarily resides.
EXISTING TECHNOLOGIES & CONSTRAINTS
 NETWORK ASSISTED GLOBAL POSITIONING SYSTEM (GPS)
 NETWORK BASED MOBILE POSITIONING
 TIME OF ARRIVAL (TOA)
 TIME DIFFERENCE OF ARRIVAL (TDOA)
GPS TECHNOLOGY
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.
NETWORK BASED MOBILE POSITIONING
 locating mobile – 3 BSs receive signal – calculate dist. between mobile & BSs-determine the position of mobile phone.
 It is carried out by LOCATION DATA PROCESSOR & BS CONTROLLER .
TIME OF ARRIVAL (TOA)
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.
 The distance is calculated by the following equation,
Ri = C τi = sqrt ( (xi – X ) 2 + (yi – Y) 2 ) where,
C – Propagation speed of electromagnetic wave,
τi – propagation of time from the mobile telephone to ith base station,
Xi, yi -- location of ith base station,
X, Y – mobile position.
TIME DIFFERENCE OF ARRIVAL (TDOA)
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
LOCATION TRACKING CURVE METHOD
 The positioning 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.
CONCLUSION
It is advantageous in that the location of a mobile telephone can be accurately tracked even in the multi-path fading and the NLOS environment .

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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. The evolution to location-dependent services and applications in wireless systems continues to require the development of more accurate and reliable mobile positioning technologies. The major challenge to accurate location estimation is in creating techniques that yield acceptable performance when the direct path from the transmitter to the receiver is intermittently blocked. This is the Non-Line-Of-Sight (NLOS) problem, and it is known to be a major source of error since it systematically causes mobile to appear farther away from the base station (BS) than it actually is, thereby increasing the positioning error.
In this paper, we present a simple method for mobile telephone tracking and positioning with high accuracy. Our paper 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 instead of the common chords defined by the circles. We use location tracking curves connecting the intersection points of the two circles which will be drawn by ordinary TOA method, instead of the common chord as in TDOA.
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 most immediate motivation for the cellular system to provide MT position is enhanced in accident emergency services. The positioning 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
1. 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.
 Increases the price and the size of the mobile telephone.
 The load on the mobile telephone is increased.
 Power consumption is high.
2. 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). Upon a request for service about the location of a specific mobile subscriber, the BSC selects the three adjacent BSs surrounding the mobile telephone for use in the location service, and these selected BSs are ready for communication with the mobile telephone.
3. TIME OF ARRIVAL (TOA)
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.