1) PLMN SERVICE AREA
The Public Land Mobile network (PLMN) is a geographical area served by one network operator and is defined as the area in which an operator offers radio coverage and possibility to access its network.
2) MSC/VLR (SERVICE AREA)
If the system has more than one MSC,the PLMN is subdivided into several MSC/VLR service areas. To be able to route calls to the right MSC and eventually to the right MS, it is necessary to know in which MSC/VLR service area the MS is.
The HLR stores the data ,about which MSC/VLR service area the MS is in. The VLR contains detailed information about all the MS:s in the MSC/VLR service area.
3) LOCATION AREA
Location area is an identity, which specifies a group of cells as defined by the technicians is called as location area.
Each MSC/VLR service area is subdivided into a number of location area (LA). Information about, in which location area an MS is registered, is also stored in the VLR together with subscriber data of all the visiting subscribers in that MSC/VLR service area.
If an MS move within the location area ,the system does not need to change the information in the subscriber register i.e.VLR and HLR.If the MS crosses over into a cell belonging to a new location area however, the system must be informed. This report done by the MS to the system is called “location updating”.
One LA may include cells from different BSC: s, and cells belonging to one BSC may be subdivided into several LA: s.
A group of neighboring cells using all the frequencies available in the system frequency band is called a cluster of cells.
Location area subdivided into a number of cells. A cell is the geographical area covered by one Base Transceiver Station. A cell is the smallest geographical entity in a PLMN.A cell could be any size, from a radius of tens of kilometers down to a radius of tens or hundreds of meters.
GSM SERVICE AREA
The GSM service area is the total geographical area in which subscriber can access the network. The more operators who sign contracts agreeing to work together, the more this area will increase.