PSFCH Padding to Maintain Sidelink Channel Occupancy Time

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Solution Overview

Problem

In wireless communication systems, particularly in LTE and NR, the discontinuation of channel occupancy time (COT) occurs due to PSFCH gaps when HARQ feedback is not transmitted, leading to inefficiencies and resource wastage, especially in wideband COT transmissions.

Innovation Solution

Implementing padding signals within PSFCH gaps of both common and dedicated interlaces to maintain COT continuity by ensuring that neither the initiating nor responding UE transmits HARQ feedback, thereby allowing for efficient resource utilization and continuous COT.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If PSFCH gaps are introduced for HARQ feedback transmission, then HARQ feedback reliability is improved, but channel occupancy time continuity deteriorates causing COT discontinuation

Engineering Contradiction:

ImproveHARQ feedback reliabilityVSAvoidchannel occupancy time continuity

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent applies the continuity principle by transmitting padding signals during PSFCH gaps to maintain COT continuity. When HARQ feedback is not transmitted in a PSFCH gap, the initiating UE transmits a padding signal to keep the channel occupied, preventing COT discontinuation and maintaining continuous useful action throughout the channel occupancy period.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The padding signal acts as an intermediary element that bridges the gap between data transmissions. It fills the PSFCH gap period without carrying HARQ feedback, thereby maintaining channel occupancy continuity while allowing the PSFCH structure to remain intact for when feedback is actually needed.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Duration of action of stationary object

If padding signals are transmitted in PSFCH gaps, then channel occupancy time continuity is improved, but resource utilization efficiency worsens due to additional padding transmissions

Engineering Contradiction:

Improvechannel occupancy time continuityVSAvoidresource utilization efficiency

Core Design Contradiction:

Duration of action of stationary objectVSProductivity

Solution Approach 1:

The patent applies local quality by making the padding signal transmission conditional and localized. Padding signals are transmitted only in specific PSFCH gaps where HARQ feedback is not required, rather than continuously in all PSFCH gaps. This selective approach maintains COT continuity only where necessary without wasting resources in gaps where feedback is transmitted.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements partial action by transmitting padding signals only in the portion of PSFCH gaps where HARQ feedback is not needed. Rather than filling all PSFCH gaps with padding, the system selectively applies padding only where it serves the continuity function, avoiding excessive resource consumption.

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If PSFCH resources are allocated for potential HARQ feedback, then HARQ feedback capability is improved, but the number of unused PSFCH resources increases when feedback is not transmitted

Engineering Contradiction:

ImproveHARQ feedback capabilityVSAvoidunused PSFCH resources

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The PSFCH resources serve multiple functions: they are allocated for potential HARQ feedback transmission but can alternatively be used for padding signal transmission when feedback is not required. This multi-functionality allows the same resources to maintain both HARQ feedback capability and COT continuity, reducing waste by adapting resource usage based on actual needs.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

When HARQ feedback is not transmitted in a PSFCH gap, those PSFCH resources are effectively recovered and reused for padding signal transmission. This prevents the resources from being completely wasted while maintaining the structural allocation of PSFCH resources for when feedback is actually needed.

Inventive Principle:

Principle #34Discarding and recovering

Data Source

PatentUS12513718B2Physical sidelink feedback channel padding

Publication Date: 2025.12.30 QUALCOMM INC

AI summary

Various aspects of the present disclosure generally relate to wireless communication. Some aspects more specifically relate to sidelink communications and PSFCH padding. In some aspects, a channel occupancy time (COT) initiating UE may obtain physical sidelink feedback channel (PSFCH) information indicating that a PSFCH transmission is to occupy a common interlace and one or more physical resource blocks. The COT initiating UE may communicate a padding signal within a PSFCH gap of the common interlace in accordance with identifying that the COT initiating UE and the responding UE are not to transmit hybrid automatic repeat request (HARQ) feedback within the PSFCH gap of the common interlace. In some other aspects, the PSFCH information may indicate that the PSFCH transmission is to occupy a dedicated interlace, and the COT initiating UE may communicate a padding signal on a PSFCH resource within the dedicated interlace.