MSC Call Recovery via Standby Route PRN Request
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Solution Overview
Problem
In traditional GSM or UMTS networks, when a Mobile Switching Center (MSC) fails, users cannot receive calls unless they update their location, leading to prolonged service interruptions as the system waits for a periodical or mobile-originated location update, which can take hours to recover.
Innovation Solution
A method and system that send a Provide Roaming Number (PRN) request through a standby route to a functioning MSC, perform pre-paging to update user data, and return a roaming number to complete the call, configuring multiple standby routes to quickly transfer service from a faulty MSC to a normal one.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the system waits for periodical or mobile-originated location update to recover service, then the location information can be updated, but the service interruption duration becomes prolonged (can take hours)
Solution Approach 1:
The patent applies preliminary action by having the HLR proactively send a Provide Roaming Number (PRN) request to the VLR before the called party updates their location. This preliminary PRN request allows the system to prepare the roaming number and establish the call routing path in advance, so when the called party becomes available, the call can be immediately routed without waiting for location update completion. This resolves the contradiction by eliminating the need to wait for periodical or mobile-originated location updates, reducing service interruption duration from hours to minutes.
2Ease of manufacture
If the HLR sends a PRN request to the faulty MSC, then the call routing can be established, but the call fails when the MSC is unavailable
Solution Approach 1:
The patent introduces the VLR as an intermediary between the HLR and the called party's service area. When the HLR sends a PRN request, it is routed through the VLR, which then provides the roaming number to the HLR. This intermediary approach allows the HLR to establish call routing without directly contacting the faulty MSC, enabling the system to route calls to available MSCs through the VLR's mediation, thus ensuring call completion success while maintaining ease of routing establishment.
3Ease of operation
If the user does not update location after MSC failure, then the user can continue using services, but the user cannot receive calls during the location update interval
Solution Approach 1:
The patent ensures continuity of useful action by having the HLR continuously monitor the status of MSCs and proactively send PRN requests to the VLR even when the called party has not updated their location. This continuous monitoring and proactive PRN request mechanism allows the system to maintain call reception capability without requiring the user to initiate location updates, thus ensuring both user service continuity and call reception reliability simultaneously.
Data Source
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AI summary
A method and a system for recovering calls in the case of network failure are provided. The method includes: a normal MSC sends a PRN request to a normal MSC through a standby route after a called party MSC fails, obtains the information about the location area of the called party, performs pre-paging according to the location of the called party, updates the user data after receiving a pre-paging response from the user, and returns a roaming number through the route directed to the normal MSC to complete the subsequent call. The system includes a transferring unit, a first VLR and an MSC. After the network fails, the mobile termination service of the user corresponding to the faulty MSC is transferred to the normal MSC. This solves the problem in the prior art that it takes even hours for the user to recover the mobile termination service after an MSC fails.