LTE to CS Domain Handover for Reduced Voice Call Setup Delay
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Solution Overview
Problem
In current communication networks, the handover process from LTE to 2G or 3G networks for voice calls often results in significant access delays and user experience issues due to the need for circuit switched fallback (CSFB), leading to prolonged wait times before a voice session is connected.
Innovation Solution
A network handover method that allows direct handover from an LTE network to a CS domain of a 2G or 3G network, eliminating the need for a common called procedure post-handover, thereby reducing wait times by generating a voice session during the handover process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UE falls back to 2G or 3G network for voice service, then voice service can be provided on LTE network, but access delay increases and user experience deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-establishing the voice session context during the handover process from LTE to 2G/3G network. The network side (MSC) proactively creates the voice session before the UE completes the fallback, so that when the UE arrives at the target network, the session is already ready and can be immediately activated without waiting for post-handover call setup procedures.
2Reliability
If common called procedure is performed after handover, then call connection is established, but wait time is prolonged and call may fail
Solution Approach 1:
The patent eliminates the need for common called procedure after handover by performing the session establishment in advance. The MSC generates the voice session during the handover process itself, based on the handover request message, so that no additional call setup procedures are needed after the UE completes the network transition.
3Loss of time
If handover from LTE to CS domain is triggered, then access delay to CS domain is reduced, but complexity of handover process increases
Solution Approach 1:
The patent merges the voice session establishment process with the handover process. The MSC combines the handling of handover request messages with the creation of voice sessions, so that a single message triggers both the handover execution and the session setup, eliminating the need for separate call setup procedures after handover.
Data Source
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AI summary
The present invention discloses a network handover method, where in a process of implementing circuit switched fallback, handover from an LTE network to a 2G or 3G network is triggered, so that UE can be directly handed over from the LTE network to a CS domain of the 2G or 3G network, and the network or the UE uses a session generated in the process in which the called party is handed over from the LTE network to the CS domain of the 2G or 3G network. Therefore, a common called procedure does not need to be performed after the UE is handed over from the LTE network to the 2G or 3G network, thereby shortening time for which a user waits before the voice session is connected.