HARQ Feedback Timing for UE-Group Common PDSCH During Random Access

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Solution Overview

Problem

Existing wireless communication systems face inefficiencies in wireless signal transmission and reception procedures, particularly in handling hybrid automatic repeat request (HARQ) feedback during contention-based random access procedures, leading to potential collisions and suboptimal resource utilization.

Innovation Solution

A method and apparatus are introduced to manage HARQ feedback reports by enabling a hybrid automatic repeat request (HARQ) process for UE-group common physical downlink shared channels (PDSCH) and deferring HARQ feedback until a second random access procedure is completed, especially during contention-based random access, ensuring timely resource allocation and reducing collisions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If HARQ feedback report is transmitted for UE-group common PDSCH, then communication reliability is improved through error correction, but collision occurs between HARQ-ACK transmission and RACH transmission

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidtransmission collision

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by detecting whether a random access procedure is ongoing before transmitting the HARQ feedback report. The UE checks the state of the random access procedure in advance and determines to postpone HARQ-ACK transmission until the random access procedure completes, thereby preventing collision between HARQ feedback and RACH transmissions.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If HARQ feedback report is transmitted immediately after PDSCH reception, then communication efficiency is improved, but transmission collision with RACH occurs

Engineering Contradiction:

Improvecommunication efficiencyVSAvoidtransmission reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies dynamics by making the HARQ feedback transmission timing adaptive based on the random access procedure state. The UE dynamically adjusts the transmission timing of HARQ-ACK reports - transmitting immediately when no random access is ongoing, but postponing when a random access procedure is detected as ongoing, thus balancing efficiency and reliability.

Inventive Principle:

Principle #15Dynamics

3Reliability

If HARQ process is enabled for UE-group common PDSCH, then data transmission reliability is improved, but feedback transmission conflicts with ongoing random access procedure

Engineering Contradiction:

Improvedata transmission reliabilityVSAvoidprocedure coordination complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies feedback by implementing a state-aware feedback mechanism where the UE monitors the random access procedure state and provides HARQ feedback accordingly. The feedback transmission is conditioned on the absence of ongoing random access procedures, creating a coordinated feedback system that avoids conflicts while maintaining data transmission reliability.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12621869B2Method and apparatus for transmitting/receiving wireless signal in wireless communication system

Publication Date: 2026.05.05 LG ELECTRONICS INC

AI summary

According to an embodiment of the present disclosure, a UE may determine not to transmit the HARQ feedback report for a UE-group common PDSCH at least during a random access procedure is on-going, even though the HARQ process has been enabled for the UE-group common PDSCH.