Sidelink Channel Access Using Adaptive Contention Window Control

Solution Overview

Problem

Existing wireless communication systems face challenges in efficiently transmitting signals, particularly in sidelink communications with high reliability requirements, where explicit hybrid automatic repeat request acknowledgment (HARQ-ACK) feedback is not available, leading to inefficiencies in channel access procedures.

Innovation Solution

A user equipment (UE) in a wireless communication system adjusts the contention window (CWp) for sidelink (SL) transmission based on priority class, using the minimum value when no previous CWp is available and the next higher allowed value when a specific CWp is used consecutively without HARQ-ACK feedback, to optimize channel access.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the same CWp value is used for consecutive PSSCH transmissions without HARQ-ACK feedback, then device complexity is reduced, but channel access efficiency deteriorates

Engineering Contradiction:

ImproveCWp management complexityVSAvoidchannel access efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent implements dynamic CWp adjustment where the contention window value changes based on transmission outcomes. When HARQ-ACK feedback is received, CWp is adjusted according to the feedback; when no feedback is received after K1 consecutive transmissions, CWp is doubled. This dynamic adaptation resolves the contradiction by making the system simple when possible but efficient when needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent introduces a feedback mechanism where the absence of HARQ-ACK feedback after K1 consecutive PSSCH transmissions triggers CWp adjustment. This feedback-based approach allows the system to maintain simple operation under normal conditions while automatically improving channel access efficiency when transmission failures are detected, thus resolving the technical contradiction.

Inventive Principle:

Principle #23Feedback

2Productivity

If CWp is adjusted frequently to optimize channel access, then channel access efficiency is improved, but device complexity increases

Engineering Contradiction:

Improvechannel access efficiencyVSAvoidCWp adjustment complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent implements dynamic CWp adjustment where the contention window value changes based on transmission outcomes. When HARQ-ACK feedback is received, CWp is adjusted according to the feedback; when no feedback is received after K1 consecutive transmissions, CWp is doubled. This dynamic adaptation resolves the contradiction by making the system simple when possible but efficient when needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the CWp parameter based on specific conditions (HARQ-ACK feedback reception or lack thereof after K1 transmissions). This conditional parameter adjustment allows the system to optimize channel access efficiency only when necessary, avoiding unnecessary complexity while maintaining performance where needed.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the contention window size is increased to reduce collisions, then reliability is improved, but transmission latency increases

Engineering Contradiction:

Improvetransmission reliabilityVSAvoidtransmission latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent implements dynamic CWp adjustment where the contention window value changes based on transmission outcomes. When HARQ-ACK feedback is received, CWp is adjusted according to the feedback; when no feedback is received after K1 consecutive transmissions, CWp is doubled. This dynamic adaptation resolves the contradiction by making the system simple when possible but efficient when needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent employs periodic CWp adjustment triggered by specific events (receipt of HARQ-ACK feedback or expiration of K1 consecutive transmissions without feedback). This event-driven periodic adjustment allows the system to maintain smaller CWp values most of the time (reducing latency) while periodically increasing reliability when transmission failures are detected.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS20260052582A1Signal transmission method and device in wireless communication system

Publication Date: 2026.02.19 WILUS INSTITUTE OF STANDARDS & TECHNOLOGY INC

AI summary

The present invention relates to a wireless communication system, and specifically to a method used by a terminal in a wireless communication system, and a wireless device therefor, the method comprising the steps of: carrying out CW adjustment in order to transmit a SL transmission; and carrying out a channel access procedure on the basis of the adjusted CW, wherein, if, with respect to the CW adjustment, the SL transmission is not associated with an explicit HARQ-ACK feedback, the adjusted CW is determined according to a proposed method.