MBS Session Maintenance During 5G to 2/3G Intersystem Handover
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Solution Overview
Problem
The challenge in maintaining Multicast Broadcast Services (MBS) sessions after intersystem changes, such as from 5G to 2/3G or during 5G-SRVCC handover from NG-RAN to UTRAN, is undefined in current wireless communication systems, leading to disruptions in service continuity.
Innovation Solution
A method where User Equipment (UE) maintains a PDU session in the 5G network, joins MBS sessions, and upon intersystem change or handover, locally releases or transfers the PDU session, determining association with the MBS session, while the network considers the UE removed from the MBS session accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If intersystem change from 5G to 2/3G or handover from NG-RAN to UTRAN is performed, then mobility and network flexibility are improved, but MBS session continuity is disrupted
Solution Approach 1:
The patent applies preliminary action by establishing MBS session parameters and configuration information before the intersystem change occurs. The source gNB prepares and forwards MBS session context to the target gNB or core network in advance, ensuring that the session can be quickly reestablished after handover without disruption to service continuity.
Solution Approach 2:
The patent uses the core network (AMF/SMF) or target gNB as an intermediary to maintain MBS session continuity during intersystem change. The intermediary receives MBS session context from the source network, stores it temporarily, and facilitates the session transfer to the target system, ensuring seamless continuity across network boundaries.
2Productivity
If PDU session is released during intersystem change, then resource allocation is optimized, but MBS service reception is interrupted
Solution Approach 1:
The patent segments the PDU session and MBS session management into independent components. The PDU session can be released for resource optimization while the MBS session context is preserved separately and reestablished independently in the target system, allowing resource efficiency without service interruption.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining MBS session context and configuration information throughout the intersystem change process. Even though the PDU session is released, the MBS service reception continues uninterrupted through preserved session parameters and rapid reestablishment in the target network.
3Reliability
If MBS session maintenance procedure is defined, then service continuity is improved, but system complexity increases
Solution Approach 1:
The patent applies universality by using existing 5G MBS session management mechanisms and signaling procedures for intersystem change. The same MBS session context structure, signaling messages, and management functions are reused across different system boundaries (5G to 2/3G, NG-RAN to UTRAN), avoiding the need for separate complex procedures while ensuring service continuity.
Data Source
AI summary
A method for maintaining MBS session when UE performs intersystem change is provided. UE maintains a PDU session in 5G network. UE then joins an MBS session for receiving MBS service over the associated PDU session. Later on, UE performs intersystem change from 5G to 2/3/4G. The PDU session is then released or transferred to a PDN connection. From UE perspective, UE determines that the released or transferred PDU session is associated with the MBS session, and therefore locally leaves the MBS session. From NW perspective, NW determines that the released or transferred PDU session is associated with the MBS session, and therefore considers the UE is removed from the MBS session.