19.1.2 Location Cancellation

09.023GPPMobile Application Part (MAP) specificationTS

19.1.2.1 General

The purpose of this process is to delete a subscriber’s record from a previous visitor location register after she has registered with a new visitor location register. Also this process is used to delete a subscriber’s record from a old SGSN after she has registered with a SGSN. The procedure may also be used if the subscriber’s record is to be deleted for other operator determined purposes, e.g. withdrawal of subscription, imposition of roaming restrictions or modifications to the subscription which result in roaming restrictions. Location cancellation can be used to enforce location updating including updating of subscriber data in the VLR or in the SGSN at the next subscriber access.

In all cases, the process is performed independently of the invoking process (e.g. Location Updating).

The service as described in subclause 8.1.3 is invoked when an HLR receives a MAP_UPDATE_LOCATION indication from a VLR other than that stored in its table for this subscriber. Also the MAP_CANCEL_LOCATION service is invoked when the HLR receives a MAP_UPDATE_GPRS_LOCATION indication from a SGSN other than stored in its table for this subscriber. Additionally the service may be invoked by operator intervention. The MAP_CANCEL_LOCATION service is in any case invoked towards the VLR or the SGSN whose identity is contained in the HLR table.

+—-+ D +—-+ D +—-+
ªVLR +———–+————ªHLR ª——-+———ªPVLRª
+—-+ +—-+ +—-+
ª ª ªßß
ª MAP_UPDATE_LOCATION ª ªßß
ª—————————->ª ªßß
ª ª MAP_CANCEL_ ªßß
ª ª ———————>ªßß
ª ª LOCATION ªßß
ª ª ªßß
ª ª ªßß
ª ª MAP_CANCEL_LOCATION ªßß
ª ª<——————— ªßß
ª ª ack ªßß
ª ª ªßß

NOTE: The service shown in dotted lines indicates the trigger provided by other MAP signalling.

Figure 19.1.2/1: Interface and services for Location Cancellation

19.1.2.2 Detailed procedure in the HLR

The location cancellation process is started by an external process as stated above. The HLR opens a dialogue with the VLR or with the SGSN whose identity is contained in the HLR table (MAP_OPEN request without any user specific parameters), sending the MAP_CANCEL_LOCATION request primitive (see figures 16.1.2/2 and 16.1.2/4), containing the parameters:

– IMSI, to identify the subscriber to be deleted from that VLR or SGSN;

  • -LMSI, which is included if available in the HLR. LMSI is not applicable between HLR and SGSN;
  • – Cancellation Type if the Cancel Location is sent to SGSN. Cancellation Type is not applicable between HLR and VLR. If the VLR receives this parameter and do not understand it this parameter shall be ignored.

The HLR then waits for the MAP_OPEN confirmation (see macro Receive_Open_Cnf, subclause 21.1), indicating either:

– reject of the dialogue (process terminates);

– reversion to version Vr when the operation is sent to SGSN (process terminates);

– reversion to version Vr when the operation is sent to VLR (process will be performed according to MAP version Vr); or

– dialogue acceptance.

When the VLR or the SGSN accepts the dialogue, it will return a MAP_CANCEL_LOCATION confirmation, containing:

– no parameter, indicating successful outcome of the procedure;

– a user error, provider error or a data error indicating unsuccessful outcome of the procedure.

In case of unsuccessful outcome or if a MAP_P_ABORT indication has been received, the HLR may repeat the MAP_CANCEL_LOCATION request later, where the number of repeat attempts and time in between are HLR operator options, depending on the error returned by the VLR or the SGSN.

19.1.2.3 Detailed procedure in the VLR

Opening of the dialogue is described in the macro Receive_Open_Ind in subclause 25.1, with outcomes:

– reversion to version Vr procedure;

– procedure termination; or

– dialogue acceptance, with processing as below.

If the VLR process receives a MAP_NOTICE indication, it terminates the dialogue by sending a MAP_CLOSE request.

If the VLR process receives a MAP_CANCEL_LOCATION indication from the HLR (see figure 19.1.2/3), the parameters are checked first (macro Check_Indication, see subclause 25.2). In case of parameter problems the appropriate error is sent in the MAP_CANCEL_LOCATION response.

If the MAP_CANCEL_LOCATION indication contains both the IMSI and the LMSI, the VLR checks whether the stored IMSI matches the received IMSI. If it does not, the VLR attempts to process the request using the IMSI received from the HLR to define the subscriber record to be deleted.

Thereafter the VLR checks whether the subscriber identity provided is known in the VLR:

– if so, the data of the subscriber are deleted from VLR table and a MAP_CANCEL_LOCATION response is returned without any parameters;

– if not, location cancellation is regarded as being successful, too, and the MAP_CANCEL_LOCATION response is returned without any parameters.

In either case, after sending the MAP_CANCEL_LOCATION response the VLR process releases any TMSI which may be associated with the IMSI of the subscriber, terminates the dialogue (MAP_CLOSE with Release Method Normal Release) and returns to the idle state.

Figure 19.1.2/2: Process Cancel_Location_HLR

Figure 19.1.2/3: Process Cancel_Location_VLR

19.1.2.4 Detailed procedure in the SGSN

Opening of the dialogue is described in the macro Receive_Open_Ind in subclause 25.1, with outcomes:

– procedure termination; or

– dialogue acceptance, with processing as below.

If the SGSN process receives a MAP_NOTICE indication, it terminates the dialogue by sending a MAP_CLOSE request.

If the SGSN process receives a MAP_CANCEL_LOCATION indication from the HLR (see figure 19.1.2/4), the parameters are checked first (macro Check_Indication, see subclause 25.2). In case of parameter problems the appropriate error is sent in the MAP_CANCEL_LOCATION response.

Thereafter the SGSN checks whether the subscriber identity provided is known in the SGSN:

– if so, the data of the subscriber are deleted from SGSN table and a MAP_CANCEL_LOCATION response is returned without any parameters;

– if not, location cancellation is regarded as being successful, too, and the MAP_CANCEL_LOCATION response is returned without any parameters.

In either case, after sending the MAP_CANCEL_LOCATION response the SGSN process releases any P-TMSI which may be associated with the IMSI of the subscriber, terminates the dialogue (MAP_CLOSE with Release Method Normal Release) and returns to the idle state.

Figure 19.1.2/4: Process Cancel_GPRS_Location_HLR

Figure 19.1.2/5: Process Cancel_Location_SGSN