PDCP Control PDU Duplication Handling in NR
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Solution Overview
Problem
In New Radio (NR) communications, the duplication of Packet Data Convergence Protocol (PDCP) control PDUs poses challenges for duplicate detection and discarding, as there is no sequence number defined in the PDU format, affecting Radio Link Control (RLC) and Medium Access Control (MAC) layer behaviors, and unclear transmission mechanisms.
Innovation Solution
A method where a processor in user equipment (UE) determines whether a PDCP entity is associated with two RLC entities and activates duplication, selecting one RLC entity to transmit PDCP control PDUs and adding a sequence number to them, enabling proper detection and discard of duplicates at the receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCP duplication is activated for PDCP control PDUs, then reliability is improved, but duplicate detection becomes impossible without sequence numbers
Solution Approach 1:
The patent changes the parameter of PDCP control PDU format by adding a sequence number field that was previously absent. This allows the receiver to detect duplicates while maintaining the control PDU functionality, resolving the contradiction between enabling duplication for reliability and the inability to detect duplicates without sequence numbers.
2Reliability
If PDCP control PDUs are transmitted to multiple RLC entities, then reliability is improved, but transmission mechanism complexity increases
Solution Approach 1:
The patent introduces dynamic selection of RLC entities for PDCP control PDU transmission based on duplication activation state. When duplication is activated, the transmitter can dynamically choose which RLC entity receives the control PDU, and the receiver dynamically determines which RLC entity's transmissions to expect, simplifying the transmission mechanism while maintaining reliability.
3Productivity
If PDCP duplication is configured, then data volume calculation becomes unclear, but resource allocation efficiency improves
Solution Approach 1:
The patent implements feedback mechanisms where the transmitter and receiver share information about duplication configuration and activation state. This feedback allows both sides to correctly calculate and report data volume for PDCP control PDUs, preventing information loss while maintaining efficient resource allocation through duplication.
Data Source
AI summary
Various solutions for handling packet data convergence protocol (PDCP) duplication with respect to user equipment and network apparatus in mobile communications are described. An apparatus may determine whether a PDCP entity is associated with two radio link control (RLC) entities. The apparatus may determine whether PDCP duplication is activated. The apparatus may select one of the two RLC entities to transmit a PDCP control protocol data unit (PDU) in an event that the PDCP entity is associated with the two RLC entities and the PDCP duplication is activated.