Location area

from Wikipedia, the free encyclopedia

Location Area ( LA ; German stay area ) describes the current location of a mobile phone within a cellular network in mobile communications ( GSM and UMTS ) .

Definition and characteristics

A location area is defined by the Location Area Identity (LAI), consisting of Mobile Country Code (MCC), Mobile Network Code (MNC) and Location Area Code (LAC, a 2-byte ID, German location area code ). So: LAI = MCC + MNC + LAC.

A location area consists of a variable number of radio cells (BTS) that are connected to the same Mobile Services Switching Center (MSC); they are usually even controlled by the same Base Station Controller (BSC). In combination with the Cell-ID (CID), which clearly differentiates the individual radio cells within a location area, LAI + CID becomes the globally unique Global Cell-ID (GCID).

The geographical size of a location area varies depending on the network density (number of BTS ), the volume of calls and data and the individual configurations specified by the network operator.

Location in the cellular network

As long as a GSM mobile phone is in "idle mode", i.e. no connection is active, the location area is the only location-related information known to the network. If the mobile phone changes to a radio cell that belongs to a different location area, a location update takes place, i.e. the network is informed that you are now in a different location area. If there is a change to another cell within the same location area, no location update takes place. This makes the LA the smallest addressable unit in which a mobile phone can be called using paging .

The exact location of the cell phone in a GSM cellular network via the CID is only known to the network when a connection is established, for example through a call or the sending or receiving of a short message. Using a “ silent SMS ”, this process can also be triggered without the user noticing. In newer third-generation cellular networks, including UMTS and CDMA2000 , the global cell ID (GCID) can also be determined by the network operator without a "silent SMS".

Individual evidence

  1. ↑ ITWissen.info: LAC :: location area code :: location area code
  2. ↑ ETSI: GSM 03.03, Numbering, addressing and identification. Retrieved January 1, 2014 .
  3. ↑ ETSI: 3G TS 29.002, Mobile Application Part (MAP) specification. Retrieved January 1, 2014 .