Location based services

Networking Basics and Technologies

1. Location Based services By: Karina Aggarwal

2. DEFINATION Q. What does  Location Based Services (LBS)  mean ? Location based services (LBS) are services offered through a mobile phone and take into account the device’s geographical location. LBS typically provide information or entertainment. Because LBS are largely dependent on the mobile user’s location, the primary objective of the service provider’s system is to determine where the user is. For Example,it can point a user to the nearest restaurant. An LBS can send an SMS message advertising a sale at a nearby shopping mall.

3. METHODS To specify the mobile user's location, one method involves using the mobile phone network. For example, the current cell ID can be used for identifying the base transceiver station (BTS) that the phone is communicating with. Once that is determined, the only thing left is to pinpoint the location of the BTS . Other systems use GPS satellites . This method is much more accurate than the one previously mentioned and are now made easier by some smartphones that already have built-in GPS receivers.

4. Another common method is the use of short-range positioning beacons . Such devices typically employ WiFi or Bluetooth technologies and are ideal for indoor LBS applications.

5. Classification The global LBS market is broadly classified on the basis of technologies, services provided, applications, end users, regions, and target audience. The technologies under LBS market constitute cell ID, E-OTD, A-GPS, E-GPS, and hybrid technology. Among the various technologies, hybrid technology is emerging and is expected to grow tremendously in the near future . The sub segments of applications include mapping, infotainment and discovery , emergency support and disaster management, leisure and social networking, location-based advertising, and tracking

6. TECHNIQUES The market research report categorizes the global Location based services market on the following basis: On the basis of Products : Hardware Software Services On the basis of Services: Consulting Managed Services System Integration Other Services On the basis of Technologies : Cell Identification (Cell-ID) Enhanced Observed Time Difference (E-OTD )

7. Observed Time Difference Of Arrival (OTDOA) Assisted GPS (A-GPS) Enhanced GPS (E-GPS) Hybrid Technology On the basis of End Users : Academia and Education BFSI Healthcare Government and Defense Retail Media and Advertisement Manufacturing Oil and Gas Transportation and Logistics

8. Triangulation It is the process of determining the location of a point by measuring   angles  to it from known points at either end of a fixed baseline, rather than measuring distances to the point directly trilateration. The point can then be fixed as the third point of a triangle with one known side and two known angles .

9. TYPES OF TRIANGULATION Denzin (1970) extended the idea of triangulation beyond its conventional association with research methods and designs. He distinguished four forms of triangulation: Data triangulation , which entails gathering data through several sampling strategies, so that slices of data at different times and social situations, as well as on a variety of people, are gathered. Investigator triangulation , which refers to the use of more than one researcher in the field to gather and interpret data. Theoretical triangulation , which refers to the use of more than one theoretical position in interpreting data.

10. Methodological triangulation , which refers to the use of more than one method for gathering data . Triangulation today is used for many purposes including   surveying navigation metrology astrometry binocular vision Model rocketry and gun direction of  weapons .

11. Applications Optical 3d measuring systems use this principle as well in order to determine the spatial dimensions and the geometry of an item. Basically , the configuration consists of two sensors observing the item. One of the sensors is typically a digital camera device, and the other one can also be a camera or a light projector. The projection centers of the sensors and the considered point on the object’s surface define a (spatial) triangle. Within this triangle, the distance between the sensors is the base  b  and must be known. By determining the angles between the projection rays of the sensors and the basis, the intersection point, and thus the 3d coordinate, is calculated from the triangular relations.

12. AlGorithms Delaunay Triangulation Polygon Triangulation 3D Triangulation

13. CGI - Cell Global Identity CGI (Cell Global Identity) is the global identity of the cell in the whole system. It is composed of four different parameters : MCC - Mobile Country Code, MNC - Mobile Network Code LAC - Location Area Code, CI - Cell Identity within the location area. CGI is sent to the mobile station (MS) as a part of the system information message (GSM Rec. 04.08). The combination MCC-MNC-LAC is also known as the location area identity (LAI ). It is a standard identifier for mobile phones cells, providing means to geographically locate connected mobile phones.

14. If a cell phone is connected to a GSM network then the position of that particular cell phone can be determined using CGI of the cell which is covering that cell phone. There is a series of related technologies that were developed based on CGI that enhances the location precision: Cell Global Identity with Timing Advance (CGI+TA), Enhanced CGI (E-CGI), Cell ID for WCDMA, Uplink Time Difference Of Arrival (U-TDOA) Any Time Interrogation (ATI), and Assisted Global Positioning System (A-GPS)

15. Enhanced cell global identity ( ecgi) Enhanced Cell ID provides the next-level of accuracy over Cell ID through the use of Radio Frequency parameters such as Timing Advance (TA) to estimate a position within the cell-sector.  In the GSM cellular mobile phone standard, timing advance value corresponds to a step change in an approximation of the number of microseconds the signal from the mobile phone requires to travel to the base transceiver station (BTS—essentially the cell tower to which the phone is connected at the time). Specifically, TA uses time offset information sent from the BTS to adjust a mobile handset's relative transmit time to correctly align the time at which its signal arrives at the BTS. These measurements can be used to determine the distance from the mobile device to the BTS further reducing the position error, as indicated in the following diagram.

16. GPS-Global Positioning System The  Global Positioning System  ( GPS ) is a space-based satellite navigation system that provides location and time information anywhere on or near the earth. The system provides critical capabilities to military, civil, and commercial users around the world. The United States government created the system, maintains it, and makes it freely accessible to anyone with a GPS receiver .

17. STRUCTURE The current GPS consists of three major segments. The U.S. Air Force develops, maintains, and operates the space and control segments. Space segment (SS ):: The space segment is composed of 24 to 32 satellites in medium earth orbit and also includes the payload adapters to the boosters required to launch them into orbit. C ontrol segment ( CS):: The control segment is composed of a master control station (MCS), an alternate master control station, and a host of dedicated and shared ground antennas and monitor stations.

18. User segment ( US):: The user segment is composed of hundreds of thousands of U.S. and allied military users of the secure GPS Precise Positioning Service, and tens of millions of civil, commercial, and scientific users of the Standard Positioning Service. APPLICATIONS Civilian Communication Navigation Military

19. AGPS-ASSISTED GPS Assisted GPS (A-GPS) is used to speed up start-up times of GPS-based positioning systems. GPS may have problems getting a lock when the signal is weak and in such a case A-GPS would assist in getting a lock. This, however, is achieved by the use of an Assistance Server, so a data connection is required and charges may apply for the data transfer . It enhances the performance of standard GPS in devices connected to the cellular network. A-GPS improves the location performance of cell phones (and other connected devices) in two ways :

20. By obtaining a faster "time to first fix" ( TTFF) By helping position a phone or mobile device

21. Working Of AGPS