tailieunhanh - Signaling System No.7 Protocol Architecture And Sevices part 48

Mobility Management Mobility management operations can be divided into the following categories | Mobility Management Mobility management operations can be divided into the following categories Location Management Paging and Search Access Management Handover Authentication Management Security Management IMEI Management Subscriber Management Identity Management Fault Recovery The following section examines the MAP operations that are used in each of these categories excluding Paging and Search Access Management Security Management and Identity Management because these categories were removed at Phase 2. Location Management To minimize transactions with the HLR it only contains location information about the MSC VLR to which the subscriber is attached. The VLR contains more detailed location information such as the location area in which the subscriber is actually roaming. See Chapter 12 Cellular Networks for more information about location areas. As a result the VLR requires that its location information be updated each time the subscriber changes location area. The HLR only requires its location information to be updated if the subscriber changes VLR. Location management operations include the following updateLocation cancelLocation sendIdentification purgeMS updateLocation This message is used to inform the HLR when an MS in the idle state has successfully performed a location update in a new VLR area. In this way the HLR maintains the location of the MS VLR area only . In Appendix L Tektronix Supporting Traffic Figure 13-3 contains a trace that shows an HLR s decode calling a VLR to perform cancel location . In Figure 13-1 the MS has roamed from a VLR area that is controlled by VLR-A to an area that is controlled by VLR-B. Note that the purgeMS operation is optional in a location update procedure. Figure 13-3. MAP Operation Sequences in a Handover Figure 13-1. Showing the MAP Operation Sequences Involved in a Location Update View full size image cancelLocation The cancelLocation operation is used to delete a subscriber s profile from the previous VLR .