NR PDCP Duplication Feedback for RLC Failure Prevention

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Solution Overview

Problem

Packet duplication at the PDCP sublayer in New Radio Access Technology (NR) leads to inefficiencies in RLC operation and radio link failure, particularly in AM mode, due to handling of duplicates across multiple carriers.

Innovation Solution

Implement novel PDCP operations to inform RLC of duplicate SDUs and prevent RLF triggering by discarding or ignoring duplicates, and ensuring successful delivery is confirmed before transmitting further duplicates, even if retransmissions reach a threshold.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If packet data convergence protocol data units are transmitted over multiple carriers simultaneously, then transmission reliability is improved, but false radio link failure triggers occur due to duplicate packets being misinterpreted as losses

Engineering Contradiction:

Improvetransmission reliabilityVSAvoidfalse failure indication

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent implements a feedback mechanism where the receiving end detects duplicate PDCP data units and sends back indication information to the transmitting end. This feedback loop allows the system to recognize that duplicates were transmitted over multiple carriers, preventing the false interpretation of duplicates as packet losses and subsequent false radio link failure triggers.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces an intermediary indication mechanism between the transmitting and receiving ends. The receiving end acts as an intermediary that identifies duplicate packets and communicates this information back to the transmitter, enabling the system to distinguish between intentional duplicates (from multi-carrier transmission) and actual packet losses.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If duplicate packet data convergence protocol data units are detected and handled, then false radio link failure triggers are prevented, but additional signaling overhead is introduced

Engineering Contradiction:

Improvefalse failure preventionVSAvoidsignaling overhead

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent extracts only the essential information needed to identify duplicates - specifically using packet counters and sequence numbers - rather than transmitting full packet content or extensive metadata. This extraction approach minimizes signaling overhead while still enabling effective duplicate detection and prevention of false radio link failure triggers.

Inventive Principle:

Principle #2Taking out (Extraction)

3Productivity

If packet data convergence protocol data unit duplicates are transmitted over multiple carriers, then transmission efficiency is improved, but difficulty in detecting actual packet losses increases

Engineering Contradiction:

Improvetransmission efficiencyVSAvoidpacket loss detection

Core Design Contradiction:

ProductivityVSDifficulty of detecting and measuring

Solution Approach 1:

The feedback mechanism provides continuous information about which packets were successfully received and which are duplicates. This feedback enables the transmitting end to distinguish between duplicates (which should not trigger retransmission) and actual packet losses (which require retransmission), maintaining accurate packet loss detection despite multi-carrier duplicate transmission.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces traditional packet loss detection mechanisms with a sequence number-based identification system. Instead of relying on complex analysis of transmitted data patterns, the system uses structured sequence numbers and counters that explicitly identify duplicates, simplifying the detection process while maintaining transmission efficiency.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP4447608B1Duplication and RLC operation in new radio access technology

Publication Date: 2026.05.13 NOKIA TECHNOLOGIES OY

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Figure 3a~3b
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AI summary

In accordance with example embodiments as described herein there is at least an apparatus and method to perform determining that at least one packet data convergence protocol data unit of a packet data convergence protocol sublayer are duplicate packet data convergence protocol data units of the packet data convergence protocol sublayer having been submitted for transmission on two or more carriers in a communication network; signaling to a control sublayer an indication of each packet data convergence protocol data unit that is a duplicate packet data convergence protocol data unit; and based on the indication, preventing a trigger of a radio link failure when a number of retransmissions based on the duplicate packet data convergence protocol data units reaches a threshold number of retransmissions. Further, there is at least an apparatus and method to perform transmitting packet data convergence protocol data unit duplicates over two or more carriers; receiving an indication that indicates packet data convergence protocol data unit has been correctly transmitted via one of two or more carriers; and upon receiving the indication, instructing to discard other packet data convergence protocol duplicates over carriers other than the one of two or more carriers with a successful delivery.