Subject: Mobile Computing

Difficulty: Medium

Marks: 4 Marks

In this case, two LAs belong to different MSCs of the same VLR. The location update procedure is as follows:

Steps 1 and 2:

• The location update request is sent from the MS to the VLR

Step 3:

• VLR updates the LAI and the MSC fields of VLR record, and derives the HLR address of the MS from the MS‘s IMSI

• VLR sends the MAP_UPDATE_LOCATION message to the HLR. It gives the following details

  • IMSI of the MS
  • Address of the target MSC (i.e., MSC2)
  • Address of the target VLR (i.e., VLR1)

Step 4:

• HLR identifies the MS‘s record by using the received IMSI
• MSC number field is updated
• An acknowledgment is sent to the VLR