Location update
With Location Update (German location update ) or location update procedure is the mobile is the sum of the technical steps which are necessary to a mobile device to provide access to a foreign network or to a new location in the current network. With the location update, the network or the network components for the new location of the mobile device is consequently updated (update). Although the term location update originally comes from the GSM world, it has also established itself for other network standards such as WLAN .
Each location update includes at least authentication and authorization of the mobile device by the local network access components. In cellular networks such as GSM, this happens e.g. B. by the local Base Transceiver Station (BTS) and the Base Station Controller (BSC), as well as the Mobile Services Switching Center (MSC), while the authentication and authorization z. B. is carried out by access point and access server. If bidirectional connections are to be guaranteed through the network, a so-called “location registration” based on the new location is also carried out. In GSM networks, this happens e.g. B. by updating the user location in the Home Location Register (HLR); B. by reporting the new location to the home agent using Mobile IP .
Cellular cellular networks
A cellular cellular network , such as B. a GSM network is divided into radio cells . The radio cells of larger mobile radio networks are typically combined into groups, one group of radio cells being called the location area . The management of a large number of location areas is taken over by an MSC in GSM mobile radio networks. The location area in which a participant is located can be used by the network as location information ("location"). The current location area can be stored in a central unit assigned to the respective participant. In GSM networks, this central unit is the home location register. If the subscriber is not in the home network, a copy of this subscriber data record is transferred to the Visitor Location Register (VLR) of the MSC that manages the location area.
Location registration
If a mobile radio subscriber changes his location to a different location area, a location update is carried out. This is initiated by the mobile device that has noticed the change in the location area. After successful authentication and authorization at the new location, the new location area is registered in the VLR of the responsible MSC. If there is not yet a subscriber data set there, for example because the new location area is in the area of another MSC, the subscriber data set is first downloaded from the HLR. After the new subscriber location has been registered in the VLR, the central subscriber data record is updated accordingly in the HLR by entering the new location area and, if applicable, the new VLR address.
There are the following reasons for a location update:
- Change of location area
- after a time specified by the network operator
- Switch on the mobile phone
Phone call
If the mobile radio subscriber is called, the MSC area in which he is located is first determined in his subscriber data record in the HLR based on the VLR address entered there. In the MSC, the location area is determined from the subscriber data and the subscriber is searched for in all radio cells in the location area. After the answer from the mobile radio device, the telephone call can then be set up.
Terminology
Originally, the term location update was used exclusively in GSM cellular networks. Due to the growing together of the different network standards with mobile radio devices with cross-network interfaces, the term is now also used in heterogeneous network structures.
See also
The following terms are related to location update :
- Handover : Change of radio cell during a telephone call, e.g. B. because of change of location. If the new radio cell belongs to another MSC, it is known as an inter-MSC handover .
- Cancel Location : Process that deletes the subscriber data from the VLR of the previous MSC during the inter-MSC handover.
- Routing Area Update : A process similar to the location update for GPRS or UMTS .