VLR

REMORA Category: V


The Visitor Location Register (VLR) is an essential component of a mobile communications network, closely associated with a Mobile Switching Centre (MSC). The primary purpose of the VLR is to manage and maintain information about the exact locations of mobile subscribers who are currently within the service area covered by a specific MSC. Here’s a detailed explanation of the VLR’s role and function:

  1. Database for Subscriber Location:
    • The VLR serves as a dynamic database that stores information about the whereabouts of all mobile subscribers currently present within the coverage area of a particular MSC.
    • Each entry in the VLR database corresponds to an individual mobile subscriber, and it includes details such as the subscriber’s identity (e.g., phone number or IMSI – International Mobile Subscriber Identity) and their current location.
  2. Routing Calls to the Right Base Station:
    • When a call or message is initiated for a mobile subscriber within the MSC’s service area, the VLR plays a crucial role in determining the subscriber’s location.
    • The VLR helps route the call or message to the appropriate base station or cell within the MSC’s coverage area where the subscriber is currently located.
    • This location-based routing ensures that the call reaches the subscriber’s current physical location.
  3. Dynamic Updating of Location:
    • The information stored in the VLR is continuously updated as mobile subscribers move within or leave the service area.
    • When a subscriber enters the service area and registers with the network (e.g., by powering on their mobile device or when crossing into the MSC’s coverage area), their current location details are added to the VLR.
    • Conversely, when a subscriber leaves the service area or switches off their device, their entry is removed or marked as inactive in the VLR to reflect their absence.
  4. Temporary Storage:
    • The VLR maintains a temporary record of subscriber locations. It doesn’t store historical location data or long-term subscriber information.
    • It focuses on the real-time management of active subscribers within the MSC’s service area.

In summary, the Visitor Location Register (VLR) is a vital database component in a mobile communications network, closely associated with an MSC. It serves as a dynamic repository of subscriber location information, allowing the network to route calls and messages to the correct base station or cell based on the current whereabouts of mobile subscribers. The VLR ensures that mobile communication is efficiently delivered to subscribers within the network’s coverage area. When subscribers move or leave the service area, their location information is updated or removed from the VLR accordingly.