MBS Handover Request Signaling with Unicast QoS Mapping
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Solution Overview
Problem
The 5G communication system does not support multicast broadcast service (MBS) and terminates it when a terminal is handed over from a source base station supporting point to multipoint to a target base station that does not, leading to service disruption.
Innovation Solution
A communication method where a source access network element sends a handover request to a target access network element with information about a unicast QoS flow corresponding to a multicast QoS flow, enabling data transmission via unicast QoS flow to ensure continuity and reliability of the MBS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the 5G communication system uses point to multipoint solution for MBS, then radio resource utilization is improved, but the MBS service is terminated when terminal is handed over to target base station that does not support point to multipoint
Solution Approach 1:
The patent changes the transmission mode parameter from point-to-multipoint to unicast during handover. When the target base station does not support point-to-multipoint, the MBS data transmission switches to unicast QoS flow, maintaining service continuity while adapting to different network capabilities.
Solution Approach 2:
The patent implements dynamic transmission mode selection based on target base station capabilities. The system dynamically switches between point-to-multipoint and unicast modes during handover, allowing the MBS service to adapt to varying network conditions and base station capabilities.
2Reliability
If dedicated resource is reserved for MBS in 4G system, then MBS service is supported, but radio resource utilization decreases
Solution Approach 1:
The patent makes unicast QoS flow resources serve dual purposes: supporting both regular unicast services and MBS services. By mapping MBS data to unicast QoS flows, the same radio resources can be dynamically allocated to different service types based on demand, eliminating the need for dedicated MBS resources.
3Device complexity
If target base station does not support point to multipoint, then device complexity is reduced, but MBS service is terminated during handover
Solution Approach 1:
The patent introduces unicast QoS flow as an intermediary transmission mechanism. When point-to-multipoint is not available at the target base station, the unicast QoS flow acts as a mediator to carry MBS data, ensuring service continuity without requiring the target base station to have advanced point-to-multipoint capabilities.
Data Source
AI summary
A communication method implemented by an apparatus includes that a source access network element sends information of a unicast quality of service (QoS) flow of a protocol data unit (PDU) session corresponding to a multicast QoS flow of a multicast broadcast service (MBS) to a target access network element in a handover procedure. The target access network element forwards the information to a session management network element. The session management network element then indicates a user plane network element connected to the target access network element to send data of the MBS to a terminal device through the target access network element and by using a resource of the unicast QoS flow corresponding to the multicast QoS flow of the MBS.