Abbreviation for Visitor Location Register. Within the
GSM Network Switching Subsystem,
the VLR is connected to the MSC via the B-Interface.
- Though initially, the VLR was designed as a separate network element
to the MSC, today the VLR is integral
part of what is called MSC/VLR. In other words, the B-interface
between MSC and VLR is no more finely specified but proprietary.
- Like the HLR, the
VLR is basically a huge database that administrates the mobility of thousands of
subscribers.
- Compared to the HLR with its more static
functions, the VLR dynamically administrates the subscribers that are currently present in
the very area that the VLR covers.
- The VLR is the peer of the mobile station
during authentication, "Location Updating" and "IMSI Attach".
Accordingly, the VLR "knows" a subscriber's precise location (location area).
- The VLR is also in charge to allocate a TMSI to a mobile subscriber.
- As the figure illustrates, each PLMN is defined by the area that all the
MSCs / VLRs cover.

[2GTS 03.02 / 2GTS 12.02 / 2GTS 12.03 ] |