Access Network Handover Mapping for MBS Service Continuity
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Solution Overview
Problem
In the handover process of user equipment (UE) between base stations, data packets are lost due to inconsistencies in the transmission progress of multicast and broadcast services (MBS) across different base stations, leading to service discontinuity.
Innovation Solution
Implement a method where access network devices determine a mapping relationship between Quality of Service (QoS) flows and radio bearers based on indication information, setting Protocol Data Unit (PDCP) serial numbers to ensure consistent data packet transmission across handovers, using techniques like one-to-one mapping or mapping all QoS flows to the same radio bearer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional handover manner is used, then handover process is simple, but service continuity cannot be ensured and data packets are lost
Solution Approach 1:
The source base station performs preliminary actions by determining the mapping relationship between QoS flows and radio bearers before handover, and forwards this mapping information to the target base station through the core network device. This preliminary configuration ensures that the target base station can immediately continue data transmission without interruption when handover occurs, thus ensuring service continuity without significantly complicating the handover process.
2Reliability
If different base stations transmit MBS service independently, then each base station operates autonomously, but transmission progress inconsistency causes data packet loss during handover
Solution Approach 1:
The source base station provides feedback information about its data transmission progress (mapping relationship between QoS flows and radio bearers) to the target base station before handover. The target base station uses this feedback to synchronize its transmission state, ensuring consistent transmission progress across base stations. This feedback mechanism maintains data packet transmission reliability while avoiding the need for complex real-time coordination during active transmission.
3Reliability
If mapping relationship is not synchronized during handover, then handover is fast, but QoS flow to radio bearer mapping inconsistency causes data loss
Solution Approach 1:
The mapping relationship between QoS flows and radio bearers is determined and synchronized in advance by the source base station before handover occurs. This mapping information is forwarded to the target base station through the core network device as part of the handover preparation. When handover executes, the target base station already has the correct mapping relationship configured, eliminating the need for post-handover synchronization and preventing data loss while keeping handover time minimal.
Data Source
AI summary
A data transmission method includes receiving, by a first access network device, local service indication information and a service identifier from a core network device. The local service indication information indicates that a service to which a data packet of a first session belongs is a local service. The data transmission method also includes sending, by the first access network device, third indication information to a second access network device. The third indication information indicates that the service is the local service.