A visitor location register (VLR) is a server that stores information on cellular users who visit your premises. It is similar to a visitor log used for office or business contact. Unlike a regular log, however, the VLR is used in a cellular network, where roaming functions are supported when the user is outside the HLR coverage area.
Visiting Location Register (VLR)
The Visiting Location Register (VLR) is a centralized device that performs interface functions between a home base station and a private base station. It is also used to store call routing and registered position information. This data is used to administer the private base station’s operations and spectrum utilization. A private base station may have a private visiting location register separate from a public one.
The Mobile Switching Center and Visiting Location Register are essential components of mobile network roaming. The latter supports roaming functions by providing trusted access to a third party for core network services such as Home Location Register lookup. Moreover, in the case of international roaming, the Mobile Switching Centre is a core network server that stores the data of authorized GSM users.
When a mobile terminal is roaming in a new area, it automatically starts a registration process. It also reports its location to the VLR. The VLR exchanges information with HLR and stores call information from MTs roaming in the area. In some cases, the VLR requires additional information from the HLR to provide supplementary services. You might also like this What Does Network File System Mean?
The visiting location register is a central database of information associated with the mobile station. It contains information such as the service identifier and the address of the private base station. This information is used to route incoming calls to the appropriate location. Once this information is updated, the mobile station receives an incoming call that is routed to the private base station’s land-line number.
After the update is complete, the new HLR sends an encrypted message to the old system and acknowledges the message. The message may contain additional security information. The message may contain a number of fields – including the TMSI. This information is used by the HLR to locate the subscriber.
Random Replacement (RR) policy
Random Replacement (RR) policy in visitor location register is a mechanism that replaces one record with another if the current one is already full. This policy is recommended for applications where the number of roaming users is more than the capacity of the VLR. This strategy decreases the size of VLR by up to 9.5%.
Most-idle replacement (MR) policy
A visitor location register (VLR) is a temporary database that stores records for roaming users. If the VLR becomes full, it can lead to a problem called VLR overflow. To overcome this problem, a new policy called the most-idle replacement (MR) policy has been proposed. This new policy requires global information and extra cost, but it overcomes VLR overflow.
The tier manager keeps track of the currently visited high and low-tier VLRs. The signaling overhead is lower for this approach, but the loss is high when the wrong tier is selected. This policy has some limitations, but it is far more efficient than the previous one.
To avoid updating external networks with location update notifications, the GLR includes a number converter 510 that converts messages to the correct HLR and VLR. The conventional method only reports the subscriber’s address to the HLR and VLR. However, the GLR maintains multiple addresses and looks to the HLR as multiple virtual VLRs.
Adaptive p-persistent backoff database failure restoration scheme
In a mobile network, a mobility database, such as a Home Location Register or Visitor Location Register, may fail and severely degrade the services of subscribers. In this paper, we propose an adaptive p-persistent backoff database fail restoration scheme for a mobility network, and validate the model by performing simulations. This backoff strategy uses demand re-registration to restore a failed VLR.
The backoff rate parameter is a function of the DP value of the data packet transmitted by the node. Choosing a high value increases the probability of collisions, and setting a low value reduces the mean time between attempts. However, it reduces the normalized throughput. As b decreases, the backoff rate parameter goes to zero and then decreases, again decreasing the throughput.
The backoff rate can be increased after a cooling-off period or recovery time. This recovery rate, however, increases more slowly than the reduction in rate due to backoff, and requires careful tuning. Moreover, the exact recovery behavior is implementation-specific and may be informed by a variety of factors.