In
mobile network
A cellular network or mobile network is a telecommunications network where the link to and from end nodes is wireless and the network is distributed over land areas called ''cells'', each served by at least one fixed-location transceiver (suc ...
s, location area identity (LAI) is a
unique identifier
A unique identifier (UID) is an identifier that is guaranteed to be unique among all identifiers used for those objects and for a specific purpose. The concept was formalized early in the development of computer science and information systems. ...
assigned to each location area of a
public land mobile network
In telecommunication, a public land mobile network (PLMN) is a combination of wireless communication services offered by a specific operator in a specific country. A PLMN typically consists of several cellular technologies like GSM/2G, UMTS/3G, L ...
(PLMN).
Overview
This internationally unique identifier is used for location updating of mobile subscribers. It is composed of a three decimal digit
mobile country code
The ITU-T Recommendation E.212 defines mobile country codes (MCC) as well as mobile network codes (MNC).
The mobile country code consists of three decimal digits and the mobile network code consists of two or three decimal digits (for example: M ...
(MCC), a two to three digit
mobile network code
The ITU-T Recommendation E.212 defines mobile country codes (MCC) as well as mobile network codes (MNC).
The mobile country code consists of three decimal digits and the mobile network code consists of two or three decimal digits (for example: M ...
(MNC) that identifies a Subscriber Module Public Land Mobile Network (SM PLMN) in that country, and a
location area code
Mobility management is one of the major functions of a GSM or
a UMTS network that allows mobile phones to work. The aim of mobility management is to track where the subscribers are, allowing calls, SMS and other mobile phone services to be deliv ...
(LAC) which is a 16 bit number with two special values, thereby allowing 65534 location areas within one GSM PLMN.
Broadcast
The LAI is broadcast regularly through a
broadcast control channel A broadcast control channel (BCCH) is a point to multipoint, unidirectional (downlink) channel used in the Um interface of the GSM cellular standard.
The BCCH carries a repeating pattern of system information messages that describe the identity, con ...
(BCCH). A
mobile station
A mobile station (MS) comprises all user equipment and software needed for communication with a mobile network.
The term refers to the global system connected to the mobile network, i.e. a mobile phone or mobile computer connected using a mobi ...
(e.g. cell phone) recognizes the LAI and stores it in the
SIM Card
A typical SIM card (mini-SIM with micro-SIM cutout)A SIM card or SIM (subscriber identity module) is an integrated circuit (IC) intended to securely store an international mobile subscriber identity (IMSI) number and its related key, which are u ...
. If the mobile station is moving and notices a change of LAI, it will issue a location update request, thereby informing the mobile provider of its new LAI. This allows the provider to locate the mobile station in case of an incoming call.
See also
*
Mobility management
Mobility management is one of the major functions of a GSM or
a UMTS network that allows mobile phones to work. The aim of mobility management is to track where the subscribers are, allowing calls, SMS and other mobile phone services to be del ...
*
GPRS roaming exchange A GPRS roaming exchange (GRX) acts as a hub for General Packet Radio Service (GPRS) connections from roaming users, removing the need for a dedicated link between each GPRS service provider. It was developed to facilitate a more efficient way for op ...
References
GSM standard
Mobile telecommunications standards
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