SRVCC Handover Management via Forward Relocation Context
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Solution Overview
Problem
Current SRVCC procedures in 5G to 4G handover and subsequent 4G to 2G/3G transitions are incomplete and cause confusion due to missing considerations for Mobile Station Classmark3 and Supported Codec List, leading to inadequate handover management and SRVCC capability assessment.
Innovation Solution
Incorporating mobility management context for SRVCC, including session transfer number and correlation mobile subscriber integrated services digital network number, into forward relocation requests to enable accurate SRVCC operation possible indications and immediate triggering of SRVCC after handover, specifically by including Mobile Station Classmark2/3 and Supported Codec List in handover messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SRVCC procedures are implemented without including Mobile Station Classmark3 and Supported Codec List in handover messages, then the handover process is simpler, but SRVCC capability assessment is inaccurate and procedures are incomplete
Solution Approach 1:
The patent applies preliminary action by including Mobile Station Classmark2/3 and Supported Codec List in the forward relocation request message during the initial 5G to 4G handover. This ensures that the target MME receives complete SRVCC capability information in advance, enabling accurate SRVCC operation possible indication determination without requiring additional subsequent signaling exchanges.
2Reliability
If SRVCC procedure waits for TAU procedure before execution, then capability information is more complete, but SRVCC procedure time increases
Solution Approach 1:
The patent performs preliminary action by transferring SRVCC capability information (Mobile Station Classmark2/3 and Supported Codec List) during the forward relocation request before the TAU procedure. This allows the target MME to determine SRVCC operation possibility immediately after receiving the handover complete message, eliminating the waiting period for TAU and reducing overall SRVCC procedure time while maintaining information completeness.
Solution Approach 2:
The patent uses the forward relocation request message as an intermediary to transfer SRVCC capability information from the source AMF to the target MME. This intermediary mechanism enables the target MME to obtain necessary capability information without waiting for the TAU procedure, thus reducing delay while ensuring accurate capability assessment.
3Adaptability or versatility
If MME acts only as control plane relay in direct 5G to 2G/3G SRVCC, then the architecture is simpler, but MME cannot support 5G to 4G handover followed by 4G to 2G/3G SRVCC
Solution Approach 1:
The patent applies universality by enhancing the MME's functionality to handle multiple SRVCC scenarios. The target MME is configured to receive and process Mobile Station Classmark2/3 and Supported Codec List from the source AMF, determine SRVCC operation possible indication, and forward this information to the access network node. This multi-functional capability enables the MME to support both direct 5G to 2G/3G SRVCC and 5G to 4G handover followed by 4G to 2G/3G SRVCC scenarios.
Data Source
AI summary
Embodiments of the present disclosure provide method and apparatus for handover management. A method performed by a first mobility management function in a first system comprises obtaining mobility management context for single radio voice call continuity (SRVCC). The method further comprises sending a forward relocation request to a second mobility management function in a second system during a handover from the first system to the second system. The forward relocation request comprises mobility management context for the SRVCC.