Non-STR MLD Channel Access Collision Prevention

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Solution Overview

Problem

In wireless local area networks (WLANs), non-simultaneous transmit and receive (non-STR) multi-link devices (MLDs) face challenges in preventing collisions between links during channel access, especially when some links are in the middle of receiving.

Innovation Solution

The method involves a channel access method where a transmitting MLD, comprising multiple stations (STAs), performs back-off operations based on the transmission/reception status of other STAs. Specifically, if a STA's back-off counter is 0 and another STA is in the middle of receiving, the first STA will perform an additional back-off operation after obtaining information about the second STA's status.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a non-STR MLD performs channel access on multiple links simultaneously, then channel utilization and productivity are improved, but collision between links occurs due to inability to receive while transmitting

Engineering Contradiction:

Improvechannel utilizationVSAvoidcollision prevention

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by having STAs exchange reception status information before performing back-off operations. The first STA obtains information about whether the second STA is in the middle of receiving a PPDU before deciding whether to perform channel access, thereby preventing collisions in advance while maintaining multi-link productivity

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If a STA performs back-off operation independently without considering other STAs' reception status, then device complexity is reduced, but collision occurs when back-off counter reaches 0 while another STA is receiving

Engineering Contradiction:

Improvechannel access controlVSAvoidcollision prevention

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent implements feedback by having STAs share reception status information with each other. The first STA receives feedback about the second STA's reception status and adjusts its back-off operation accordingly, maintaining simple device complexity while improving collision prevention through inter-STA communication

Inventive Principle:

Principle #23Feedback

3Reliability

If the first STA performs additional back-off operation when BC is 0 and second STA is receiving, then collision prevention is improved, but channel access efficiency deteriorates due to extended waiting time

Engineering Contradiction:

Improvecollision preventionVSAvoidchannel access delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies partial action by performing additional back-off operation only when necessary - specifically when the back-off counter reaches 0 and the other STA is in the middle of receiving. This selective application prevents unnecessary delays while ensuring collision prevention only when actually needed

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS20250168884A1Channel access of non-STR MLD in multi-link

Publication Date: 2025.05.22 LG ELECTRONICS INC

AI summary

A transmitting multi-link device (MLD) in a wireless local area network system enables a first station (STA) to perform a back-off operation again without transmitting PPDU, if a second STA is in the middle of receiving even when a back-off counter (BC) of the first STA becomes 0. The first STA and the second STA are included in the same transmitting MLD. The first STA operates on a first link and the second STA operates on a second link. The first and second links are included in a non-simultaneous transmit and receive (NSTR) link pair.