Priority-Based UE Feedback Triggering for Half-Duplex NAK Conflicts

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Solution Overview

Problem

In wireless communication systems, particularly in half-duplex mode, user equipment (UE) faces challenges in transmitting negative acknowledgement (NAK) messages due to simultaneous reception and transmission conflicts, leading to data loss and potential congestion in multicast or broadcast environments.

Innovation Solution

UEs determine whether to transmit NAKs based on priority levels of incoming messages, using probabilistic frameworks and congestion thresholds, to avoid conflicts and reduce congestion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE transmits the NAK message at the scheduled time, then the feedback transmission is timely and reliable, but the reception of the other packet is punctured resulting in data loss

Engineering Contradiction:
Improvefeedback transmission reliabilityVSAvoiddata loss
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The UE performs preliminary checking before transmitting the NAK message to determine if a packet reception is scheduled at the same time. This advance detection allows the UE to prevent the harmful transmission puncturing the received packet, thereby avoiding data loss while maintaining feedback reliability when conditions permit.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the NAK transmission decision based on real-time scheduling information. The UE checks whether packet reception is scheduled at the feedback transmission time and adapts its transmission behavior accordingly, enabling flexible control to avoid conflicts between transmission and reception in half-duplex mode.

Inventive Principle:
Principle #15Dynamics

2Reliability

If the UE transmits NAK messages in multicast or broadcast environments, then decoding failures are reported, but congestion is caused in the system

Engineering Contradiction:
Improvedecoding failure reportingVSAvoidsystem congestion
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The UE transmits the NAK message only when necessary - specifically when decoding fails and no packet reception is scheduled at the feedback time. This partial action approach avoids unnecessary NAK transmissions that would cause congestion, while still reporting actual decoding failures to maintain reliability.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The system uses feedback mechanisms where the UE reports decoding failures through NAK messages, but this feedback is conditioned on avoiding transmission conflicts. The base station receives these controlled feedback signals to understand which packets need retransmission without being overwhelmed by excessive NAK traffic in multicast or broadcast scenarios.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3909174B1Priority-based feedback triggering
Publication Date: 2025.10.29 QUALCOMM INC
  • EP3909174B1 patent drawingFigure 1
  • EP3909174B1 patent drawingFigure 2
  • EP3909174B1 patent drawingFigure 3

AI summary

Methods, systems, and devices for wireless communication are described. A user equipment (UE) may utilize priority levels associated with packets or transmissions to determine whether to transmit feedback for a received transmission. The UE may compare priority levels between a transmission subject to a feedback condition and a transmission scheduled to be received when the feedback is scheduled to be transmitted to determine whether to send the feedback. The UE may communicate with the transmitting device according to the comparison and the determining. The UE may determine signal conditions causing a NAK and determine to send the NAK based on the signal conditions.