MBS Handover QoS Flows for Seamless 5G Service Continuity
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Solution Overview
Problem
In 5G networks, user equipment (UE) experiences disruption in multicast broadcast services when moving from a base station supporting MBS to one that does not, requiring a switch to unicast mode, which disrupts service continuity.
Innovation Solution
A method for implementing multicast broadcast service handover by obtaining a PDU session associated with the MBS session and establishing quality of service flows using SMF and MB-SMF, ensuring continuity by transitioning to a unicast PDU session when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UE switches to unicast transmission mode when moving from MBS-supporting base station to non-MBS base station, then service continuity is maintained, but system complexity increases
Solution Approach 1:
The source base station performs preliminary actions by obtaining the PDU session associated with the MBS session and acquiring quality of service flow information before the handover occurs. This preparation ensures that when the UE switches to the target base station, the necessary session context and QoS parameters are already ready, enabling seamless transition without increasing procedural complexity at the target side.
Solution Approach 2:
The PDU session acts as an intermediary mechanism that bridges the MBS session and the target base station. By establishing a unicast PDU session at the target base station with the same S-NSSAI and DNN as the MBS session, the system maintains service continuity while using the PDU session as an intermediate structure that simplifies the handover process.
2Reliability
If UE switches to unicast mode for MBS service, then service availability is ensured, but transmission efficiency decreases
Solution Approach 1:
The system changes the transmission mode parameter from multicast to unicast when the target base station does not support MBS. By maintaining the same PDU session parameters (S-NSSAI, DNN) and establishing quality of service flows with equivalent QoS characteristics, the system ensures service availability while minimizing the impact on transmission efficiency through parameter preservation.
3Reliability
If MBS session is established on source base station, then service quality is improved, but handover flexibility is reduced
Solution Approach 1:
The system implements dynamic adaptation during handover by detecting whether the target base station supports MBS. If MBS is supported, the session continues in multicast mode; if not, it automatically transitions to unicast mode via PDU session establishment. This dynamic behavior maintains service quality while enhancing handover adaptability to different network conditions.
Solution Approach 2:
The solution applies local quality by maintaining MBS session characteristics (QoS parameters, S-NSSAI, DNN) locally at the PDU session level in the target base station. This allows the system to preserve the quality benefits of MBS even when the radio access network does not support it, by localizing the session management functions.
Data Source
AI summary
Embodiments of the present disclosure provide a method for implementing multicast broadcast service handover at a computer device acting as user equipment. The method includes: obtaining a PDU session associated with the MBS session, S-NSSAI of the PDU session being the same as S-NSSAI of the MBS session, and a DNN of the PDU session being the same as a DNN of the MBS session; obtaining an MBS session identity of the MBS session; obtaining, from an MB-SMF according to the MBS session identity, quality of service flow information corresponding to the activated MBS session; and establishing, on the PDU session according to the quality of service flow information corresponding to the activated MBS session, a quality of service flow corresponding to the activated MBS session, the quality of service flow corresponding to the activated MBS session including one or more quality of service flows.