GSM tracking

from Wikipedia, the free encyclopedia

GSM positioning refers to the determination of the location of a device ( mobile phone ) that is switched on and logged into a radio network and operated on the basis of the Global System for Mobile Communications (GSM ) via the cellular network .

Basics

The position of a cell phone is known to the cell phone operator due to the permanent registration on the network within certain accuracy limits. In standby mode, it is at least given by the assignment to the currently used location area . This information is updated regularly when the mobile station (mobile phone) moves and is stored in a database, the Home Location Register (HLR) . During conversation or data traffic (SMS, MMS), the position of a cell phone with a known phone number ( SIM card ) can be determined more precisely, since at least the cell ID of the active base station (cell phone transmitter) is known here. There are several refinements to this.

Depending on the application, GSM positioning represents a simple alternative to the Global Positioning System (GPS) , as no additional infrastructure is required for the mobile device. However, compared to location determination using GPS, GSM positioning is usually less precise, as the signals used to determine the location have system-related tolerances and, due to the infrastructure used, factors such as strongly changing propagation conditions, topography of the underlying cellular network, geographical conditions and equipment of the the end device used can influence the result.

variants

A GSM localization can be done with different measurement methods, whereby the available possibilities differ and complement each other with regard to the accuracy, the necessary hardware expenditure in the mobile radio network and the requirements for the end device.

  • Method without additional equipment, neither on the power supply nor on the device side
    • Cell ID or Cell of Origin : This method is not specified by the 3GPP , but was and is used by network operators for rough position determination. With this method, only the cell in which the terminal is located at the time of the measurement is determined and its position is used. No changes whatsoever are necessary on the network or terminal side, but the accuracy achieved is low and is directly related to the density of the base stations.
  • Methods with mains-side but without additional equipment on the device side
    • Timing Advance (TA): With this method, the position of the terminal is determined based on the position of the radio cell used and the Timing Advance parameter, which specifies the runtime of the radio signal between the base station and the mobile device (there and back). However, since the timing advance is only transmitted in steps of 3.7 µs due to the system, the distance between the mobile device and the base station can only be determined in steps of approx. 550 m ( speed of light × 3.7 µs / 2 ).
    • Uplink Time Difference of Arrival (U-TDOA): With this method, the position of the terminal is determined based on the transit times of the signals from the terminal to certain points in the mobile network, the so-called Location Measurement Units (LMU).
  • Methods with additional equipment on the mains and device side
    • Enhanced Observed Time Difference (E-OTD): With this method, the position of the end device is determined on the basis of runtimemeasurementsfrom several neighboring base stations carried out by the end device.
    • Global Navigation Satellite System (GNSS): With this method, the position of the device is determined by the device itself and forwarded to the cellular network. The end device determines its position with the help of any satellite-supported system for determining position ( GPS , Galileo , GLONASS , QZSS ).
      • A special form of this process is Assisted GNSS (A-GNSS), in which the auxiliary data necessary for determining the position are made available by the cellular network. When referring to this method, instead of the general name GNSS, the name of the satellite navigation system used in the respective case is normally used, e.g. A-GPS .

The accuracy of the determined positions is between several kilometers when using Cell ID under unfavorable circumstances, 25 m for E-OTD and U-TDOA and less than 5 m when using GNSS .

use cases

  • Location-based services : The user is provided with location-dependent information, for example information on the nearest pharmacy, the cinema program or nearby restaurants.
  • Location of stolen or lost devices: Despite the system-related inaccuracies, stolen or lost devices can be found more easily.
  • Location determination and tracking of objects and people: The location of objects or people can be determined using small and lightweight GSM devices (without telephony function). So parents can z. B. find out the whereabouts of your children or the location of a stolen bicycle or motor vehicle can be determined. Cell phone location is possible free of charge for O 2 customers , provided that the cell phone finder service located in the customer area of ​​the website is used. The automatic monitoring of people using their mobile device, for example a spouse without their consent, is a violation of their informational self-determination .
  • Fleet management for transport companies
  • Location determination after emergency calls: With newer smartphones, the location is already recorded via satellite using AML and transmitted to the control center via the cellular network. If the coordinates are not received automatically, the location of the caller can be determined at the instigation of the emergency services. The use for emergency services enables accident victims to be found quickly, as they often do not know their whereabouts exactly or give them incorrect information.
  • Police investigations: In the course of police investigations into serious criminal offenses or in the event of imminent danger , a device can be located after a prior judicial order. A special case is the silent SMS , with which the network can be forced to precisely locate a mobile phone without the user being aware of the establishment of a connection. This procedure is used in criminal prosecution as a tool for the police, with reference to “imminent danger” this is sometimes done without judicial review. However, this practice is controversial. According to information from federal authorities, over 1.7 million silent SMS messages have been sent in Germany to locate suspicious people in recent years. In Austria in 2015 the police spoke of a "cell phone tracking device" to search for a lost hiker.
  • German customs use their Patras system to locate suspicious people.

See also

  • IMEI serial number for the unique identification of mobile radio devices
  • IMSI for the unique identification of network subscribers in GSM and UMTS cellular networks
  • IMSI catcher for eavesdropping on cell phone customers
  • SIM card to identify the user in the cellular network
  • Stealth Ping - also Silent SMS or Silent SMS for the location of cell phones up to the creation of movement profiles
  • Cell-ID is a method of mobile positioning in the GSM cellular network
  • Patras (customs software) - secret location system of the German customs, operated in cooperation with mobile network operators, exact functionality is not known

Individual evidence

  1. ↑ a b 3GPP TS 22.071: Location Services; Service description; Stage 1; Release 8.1.0. (ZIP / DOC; 110 KB) December 18, 2008, accessed on September 15, 2009 (English).
  2. ↑ 3GPP TS 45.010: Radio subsystem synchronization; Release 8.4.0. (ZIP / DOC; 207 KB) June 12, 2009, accessed on September 15, 2009 (English).
  3. ↑ a b 3GPP TS 43.059: Functional stage 2 description of Location Services in GERAN; Release 8.1.0. (ZIP / DOC; 381 KB) September 23, 2008, accessed on September 15, 2009 (English).
  4. ↑ heise-online: "Public prosecutor's office criticizes" spy SMS "from the police", April 6, 2003
  5. ↑ http://kaernten.orf.at/news/stories/2740710/ Hikers found dead at the foot of rock face, orf.at, November 5, 2015, accessed November 5, 2015.