Camping in an exclusive cell
View Patent ↗In a mobile communications system exclusive location areas comprising exclusive cells are defined in order to separate cells from the mobile stations not belonging to the user group allowed to camp in the cell and still to allow emergency calls for all mobile stations in these cells. During location update it is checked whether the cell belongs to an exclusive location area ( 202 ) and if it does, it is determined whether or not the subscriber is allowed to camp in the cell.
1. A method, comprising:
determining, by a mobile station, that a location area broadcast by a Base Station Subsystem (BSS) has changed and triggering, by the mobile station, a location update procedure when the location area broadcast has changed, the BSS comprising a plurality of cells;
receiving, by a Mobile Switching Center (MSC), a Location Area Code (LAC) and Location Service Area Identifier (LSA-ID) of one of the cells in the BSS in which the mobile station wants to camp, and an identity of the mobile station;
checking, by the MSC, whether the received LAC is an Exclusive Access Location Area Code (EA-LAC); and
continuing the location update if the LAC is not an EA-LAC or, if the LAC is an EA-LAC, retrieving the LSA-ID from a Visitor Location Register (VLR), comparing the retrieved LSA-ID with the LSA-ID of the cell received by the MSC and, if there is a match, accepting the location update; else rejecting the location update and displaying a message on the mobile terminal that roaming is not permitted by the mobile station in the location area,
wherein all the cells in the location area are exclusive access cells or all of the cells in the location area are non-exclusive access cells.
2. The method according to claim 1 , wherein the identity of the mobile station is retrieved from an International Subscriber Mobile Identity (IMSI) within a Subscriber Identity Module (SIM) card in the mobile station.
3. The method according to claim 1 , wherein the checking by the MSC comprises comparing the received LAC to stored exclusive LACs.
4. The method according to claim 1 , wherein the VLR is within a Network SubSystem (NSS).
5. The method according to claim 1 , wherein the EA-LAC is indicative of an exclusive cell in which only mobile stations belonging to a specified user group are permitted to camp.
6. The method according to claim 5 , wherein a mobile station not belonging to the specified user group may still make emergency calls within the exclusive cell.