PDCP Entity Redelivery Mechanism for 5G Handover Data Integrity
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Solution Overview
Problem
In 5G mobile communications systems, data packet loss occurs due to the preprocessing of the PDCP entity when a cell handover happens, as the PDCP entity does not re-establish sequence numbers and fails to retransmit preprocessed data, leading to loss of data packets.
Innovation Solution
The PDCP entity determines and redelivers service data units (SDUs) associated with sequence numbers that have not been transmitted through the air interface by delivering protocol data units (PDUs) to the RLC entity, using indication information and maintaining count values from before the handover to ensure data integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the PDCP entity preprocesses data packets before air interface transmission, then transmission efficiency is improved, but data packet loss occurs during cell handover
Solution Approach 1:
The patent applies preliminary action by having the PDCP entity pre-process data packets (compression, encryption) before transmission. The innovation adds a re-delivery mechanism when handover is detected, ensuring pre-processed packets are retransmitted to the new cell. This resolves the contradiction by maintaining the efficiency benefit of preprocessing while adding reliability through conditional re-delivery.
Solution Approach 2:
The patent implements feedback by monitoring handover events and transmission status. When a handover is detected or acknowledged, the system feedbacks to the PDCP entity to re-deliver packets that were pre-processed but not yet transmitted. This feedback loop ensures reliability without sacrificing the initial preprocessing efficiency.
2Device complexity
If the PDCP entity does not re-establish sequence numbers during handover, then processing complexity is reduced, but data integrity is compromised
Solution Approach 1:
The patent extracts the sequence number re-establishment requirement from the general PDCP re-establishment process. Instead of fully re-establishing PDCP (which would increase complexity), the system selectively handles only the sequence number continuity aspect by re-delivering packets with their original sequence numbers intact. This maintains data integrity while avoiding the complexity of full PDCP re-initialization.
Solution Approach 2:
The patent applies partial action by performing only the necessary sequence number preservation through re-delivery, rather than complete PDCP re-establishment. This partial measure is sufficient to maintain data integrity during handover without incurring the full complexity overhead of complete protocol layer re-initialization.
3Measurement precision
If the PDCP entity restarts packet loss timer after re-establishment, then packet loss detection is improved, but data packets may be incorrectly discarded
Solution Approach 1:
The patent applies local quality by differentiating the timer behavior based on the specific handover context. For packets that were pre-processed and need re-delivery, the timer is not restarted to prevent incorrect discarding. For other packets, normal timer operation continues. This localized differentiation maintains detection accuracy where needed while preserving reliability where re-delivery is occurring.
Data Source
AI summary
This application provides a data processing method and apparatus, and a computer storage medium. When a PDCP entity over a UM DRB is re-established, or when a cell handover occurs and the PDCP entity over a UM DRB uses a key used before the handover, the PDCP entity determines a first SDU, where the first SDU is an SDU that is associated with a sequence number by the PDCP entity but whose corresponding data has not been transmitted through an air interface; and delivers a PDU corresponding to the first SDU to an RLC entity. Data corresponding to the first SDU is redelivered, to avoid a data packet loss caused by preprocessing of the PDCP entity.