Target RAN Cell Selection for Fast UE Return
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Solution Overview
Problem
Existing mechanisms for returning user equipment to a source radio access network after a CS service via a target radio access network are too slow, leading to poor transmission quality and dropped calls.
Innovation Solution
A method and device in a target radio access network that receives a request for service, connects with user equipment, receives information about source cells, and uses this information to select and return the user equipment to a specific source cell after service termination, utilizing PS handover, blind PS handover, Cell Change Order, or redirect at release procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If existing mechanisms are used to return user equipment to the source radio access network after CS fallback, then the user equipment can return to the source network, but the return process is too slow causing poor transmission quality and dropped calls
Solution Approach 1:
The source E-UTRAN cell information is provided to the target RAN in advance during the PS handover preparation phase, before the CS service actually terminates. This allows the target RAN to have the necessary information ready to quickly return the UE to the source network without delay, resolving the contradiction between return speed and transmission quality.
2Adaptability or versatility
If information about source cells is exchanged during handover preparation, then the target radio access network can select an appropriate source cell for return, but the signaling complexity increases
Solution Approach 1:
The MME acts as an intermediary that facilitates the exchange of source E-UTRAN cell information between the source E-UTRAN and target RAN during the handover preparation phase. This intermediary approach allows the information exchange to occur through existing standardized interfaces without requiring direct complex signaling between the source and target radio access networks, thus maintaining adaptability while managing signaling complexity.
Data Source
AI summary
A device receives a request for a service for a user equipment associated with a source radio access network, and establishes a connection with the user equipment via a circuit switched fallback procedure. The device also receives, from the source radio access network, information associated with one or more source cells, and provides the service to the user equipment through a target radio access network. The device further uses the information to select one of the one or more source cells for the user equipment to return after the service terminates, terminates the service, and returns the user equipment to the selected source cell.