LR (Location Register)

Introduction

Location Register (LR) is a critical component in a cellular network. It is a database that stores information about the location of each mobile subscriber in the network. The Location Register is essential for the proper functioning of the network, as it enables calls and messages to be routed to the correct mobile device. In this article, we will explain in detail what a Location Register is, how it works, and its different types.

What is a Location Register?

In a cellular network, a Location Register (LR) is a database that contains information about the current location of each mobile subscriber. This information includes the current cell or location area where the subscriber is currently located. The LR is an essential component of the mobile network, as it allows the network to route calls and messages to the correct mobile device.

The LR is divided into two types: Home Location Register (HLR) and Visitor Location Register (VLR). The HLR is responsible for storing the permanent subscriber information, while the VLR stores the temporary information of the subscribers who are currently located in the VLR's coverage area.

Home Location Register (HLR)

The HLR is the central database that contains information about all subscribers registered in a particular cellular network. The HLR stores the permanent subscriber information, such as the International Mobile Subscriber Identity (IMSI), the Mobile Station International ISDN Number (MSISDN), and the subscriber's current location area.

The IMSI is a unique identifier assigned to each subscriber, which is used to identify and authenticate the subscriber when they connect to the network. The MSISDN is the subscriber's phone number, which is used to route calls and messages to the subscriber.

The HLR also stores the subscriber's service profile, such as the type of services they have subscribed to, and any restrictions or preferences they may have specified. The HLR also stores information about the subscriber's billing, such as their billing address, billing preferences, and payment history.

When a subscriber makes a call or sends a message, the network uses the HLR to retrieve the subscriber's information and route the call or message to the correct destination. The HLR is also responsible for updating the subscriber's location information in the LR when they move to a new location area.

Visitor Location Register (VLR)

The VLR is a temporary database that contains information about subscribers who are currently located in the VLR's coverage area. When a subscriber enters a new location area, their information is stored temporarily in the VLR.

The VLR stores the subscriber's current location area, the Mobile Station Roaming Number (MSRN), and the subscriber's service profile. The MSRN is a temporary number assigned to the subscriber by the VLR, which is used to route calls and messages to the subscriber while they are located in the VLR's coverage area.

The VLR is responsible for authenticating and authorizing subscribers who are roaming in the VLR's coverage area. When a subscriber makes a call or sends a message, the network uses the VLR to retrieve the subscriber's information and route the call or message to the correct destination.

When a subscriber leaves the VLR's coverage area, their information is deleted from the VLR, and their location information is updated in the HLR.

How does the Location Register work?

The Location Register works by maintaining a database of all the subscribers registered in the network and their current location information. When a subscriber makes a call or sends a message, the network uses the LR to retrieve the subscriber's information and route the call or message to the correct destination.

The LR works in conjunction with other network components, such as the Base Station Controller (BSC) and the Mobile Switching Center (MSC). The BSC is responsible for managing the radio resources in the cell, while the MSC is responsible for managing the switching of calls and messages between the different cells in the network.

When a subscriber moves from one location area to another, the LR is updated with their new location information. The network uses this information to route calls and messages to the subscriber's current location.

For example, if a subscriber moves from one cell to another while making a call, the LR is updated with their new location information. The network then uses this information to route the call to the new cell, allowing the subscriber to continue the call without interruption.

Types of Location Registers

There are two main types of Location Registers in a cellular network: Home Location Register (HLR) and Visitor Location Register (VLR).

Home Location Register (HLR)

The HLR is the central database that stores permanent subscriber information, such as the subscriber's IMSI, MSISDN, and service profile. The HLR is responsible for managing the subscriber's billing information, service subscriptions, and preferences. The HLR also stores the subscriber's current location information, which is updated when the subscriber moves to a new location area.

The HLR is responsible for routing calls and messages to the correct destination based on the subscriber's location information. The HLR is also responsible for authenticating and authorizing subscribers when they connect to the network.

Visitor Location Register (VLR)

The VLR is a temporary database that stores subscriber information for subscribers who are currently located in the VLR's coverage area. The VLR stores the subscriber's current location information, service profile, and temporary MSRN.

The VLR is responsible for authenticating and authorizing roaming subscribers who are located in the VLR's coverage area. The VLR is also responsible for routing calls and messages to the correct destination based on the subscriber's current location information.

Conclusion

In conclusion, the Location Register is an essential component of a cellular network that stores subscriber location information. The LR consists of two main types: Home Location Register (HLR) and Visitor Location Register (VLR). The HLR stores permanent subscriber information, while the VLR stores temporary subscriber information for subscribers who are located in the VLR's coverage area.

The LR is responsible for routing calls and messages to the correct destination based on the subscriber's location information. The LR works in conjunction with other network components, such as the BSC and the MSC, to provide seamless connectivity and reliable network performance for subscribers.

The LR is a critical component in ensuring the proper functioning of the cellular network and providing subscribers with uninterrupted connectivity and services.