GPS-IN MOBILE NETWORKS

CONTENTS INTRODUCTION TO GPS OVERVIEW OF GPS. HOW MOBILE PHONE SYSTEM WORKS. HOW LBS WORKS. PROBLEMS WITH MOBILE POSITIONING.

INTRODUCTION TO GPS GPS stands for Global Positioning System. It is a constellation of 24 well-spaced satellites that orbit the earth and make it possible for people with ground receivers to pinpoint their geographic location. the location accuracy is anywhere from 1 to 100 Mt/Km/Mile depending on the type of equipment used. GPS is an only geostationary satellite based positioning system. GPS is founded by and controlled by the U. S. Department of Defense (DOD). While there are many thousands of civil users of GPS worldwide, the system was designed for and is operated by the U. S. military.

GPS receivers enable users to geographically locate their position anywhere on the surface of the earth through the assistance of GPS satellite. Over the past decade, global positioning system (GPS) technology has evolved from a sophisticated and expensive geographic positioning system .

GPS is based on 24 satellites and 5 monitoring stations around the world that enable the satellites to broadcast a signal that can be used as a reference in determining the position of user. Global Positioning System is the only system today able to show you your exact position on the Earth anywhere, in any weather, anytime. GPS satellites, 24 in all, orbit at 11,000 nautical miles above the Earth. Ground stations located worldwide continuously monitor them. The satellites transmit signals that can be detected by anyone with a GPS receiver. Using the receiver, you can determine your location with great precision .

OVERVIEW OF GPS There are currently two public GPS systems. -The NAVSTAR system -The GLONASS system The NAVSTAR system is owned by the United States and is managed by the Department of Defense. The GLONASS system is owned by the Russian Federation.

GPS consist of three parts. -The space segment -The user segment -The control segment The space segment  It consists of satellites.Each one moves in its own orbit. These space vehicles (SVs) send radio signals from space. The user segment  It consists of receivers, which you can hold in your hand or place it anywhere else. It consists of the GPS receivers and the usercommunity GPS receivers convert SV signals into position, velocity, and time estimates.

 Four satellites are required to compute the four dimensions of X, Y, Z (position) and Time. GPS receivers are used for navigation, positioning, time dissemination, and other research. The control segment  It consists of ground stations (five of them, located around the world) that make sure the satellites are working properly.

HOW MOBILE PHONE SYSTEM WORKS. 1 AUC MPC MSC HLR BSC VLR BTS EIR SIM Switching Subsystem Mobile station with SIM-card Base station subsystem OMC

MOBILE PHONE POSITIONING Mobile telephone systems keep track of the users. The system always knows where you are. Automatic when the phone activates Information from the mobile operator is sent to a security center.  Privacy, personal integrity aspects Several different technologies.  Depends on the mobile system.

Time of Arrival

Time Difference of Arrival

Cell ID All cells have an ID which is centrally assigned. 1 All networks have a number in the ITU global numbering plan. 1 6 7 2 5 3 4

HOW LBS WORKS Template database Application server Positioning service Request with identity Content database HTTP API Application Response with position Response with positioned information Request with identity or appendix HTTP API Mobile positioning centre mobile phone

TRANSFORMATION OF DATA TO MAP Transformation engine Transformation sheet library Web feature server GML content Styled maps

Problems with mobile phone positioning. Relies on the mobile telephone infrastructure  Some operators may not be ready Low precision  Depends on cell size, antenna configuration Battery life and malicious disconnection  Requires the phone to be on to work

Advantages of mobile phone positioning. Nearly ubiquitous (at least in urban areas) Works indoors  To a large extent No user action required to start positioning Position history can be registered

General problems of persistent positioning. Giving up privacy  Even if it is to a trusted party  How to prevent misuse? System needs to be 100 % up  Only telecom companies have this kind of experience  Nobody can foresee when the system is needed

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