PDCP MBS Bearer Handling for Lossless 5G Handover
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Solution Overview
Problem
Existing mobile communication systems face challenges in supporting multicast and broadcast services (MBS) efficiently, particularly in next-generation systems with high frequency bands, leading to data loss during handovers and mode transitions.
Innovation Solution
A method and apparatus are provided to support MBS services by configuring multicast and unicast bearers, with specific data processing methods at the PDCP, MAC, and RLC layers, enabling seamless transitions between RRC modes and minimizing data loss during handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCP re-establishment is performed during handover or mode transition, then service continuity is improved, but data loss occurs due to initialization of state variables
Solution Approach 1:
The patent changes the state of PDCP state variables based on the RLC mode parameter. When RLC AM mode is detected, the patent prevents initialization of PDCP state variables during PDCP re-establishment, thereby maintaining data continuity and avoiding data loss while ensuring service continuity.
Solution Approach 2:
The patent preserves the existing PDCP state variables by copying/maintaining them during re-establishment when RLC AM mode is active, rather than reinitializing them. This allows the system to retain valuable state information and avoid data loss while maintaining service continuity.
2Stability of the object's composition
If PDCP state variables are reinitialized during re-establishment, then system state consistency is improved, but data loss increases
Solution Approach 1:
The patent modifies the reinitialization behavior of PDCP state variables based on the RLC mode parameter. When RLC AM mode is detected, the patent changes the parameter to prevent reinitialization, thereby maintaining both system state consistency through alternative means and avoiding data loss.
Solution Approach 2:
The patent performs preliminary checking of the RLC mode before executing PDCP re-establishment. By detecting RLC AM mode in advance, the patent can prepare to preserve state variables and avoid data loss while still maintaining system consistency through controlled re-establishment procedures.
3Reliability
If MBS bearer is configured with RLC AM mode, then data transmission reliability is improved, but uplink retransmission overhead increases
Solution Approach 1:
The patent changes the effective behavior of PDCP re-establishment based on the RLC mode parameter. When RLC AM mode is configured for MBS bearer, the patent modifies the re-establishment procedure to preserve state variables, thereby reducing the need for uplink retransmissions and reducing energy overhead while maintaining the reliability benefits of RLC AM mode.
Data Source
AI summary
The disclosure relates to a communication technique for fusing a 5G communication system with IoT technology to support higher data rate after the 4G system and a system thereof. The disclosure may be applied to an intelligent service (e.g., smart home, smart building, smart city, smart or connected car, healthcare, digital education, retail, security and safety related services, etc.) based on 5G communication technology and IoT-related technology. The disclosure discloses a method for allowing a UE to normally receive a MBS service in various scenarios.