EMLSR Channel Access Collision Prevention
Solution Overview
Problem
In wireless local area networks (WLANs) following IEEE 802.11 specifications, collisions occur when multiple stations affiliated with a multi-link device initiate frame exchanges without performing a backoff procedure after receiving group-addressed MPDUs, leading to undesirable interference on EMLSR links.
Innovation Solution
Implementing a method where a first multi-link device (MLD) determines overlap between frame receptions and exchanges on multiple links, either deferring or refraining from initiating frame exchanges upon backoff timer expiration or receiving soliciting frames, ensuring coordinated channel access to prevent collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple STAs affiliated with a non-AP MLD initiate frame exchanges after receiving group-addressed MPDUs without performing backoff procedure, then channel utilization is improved, but collision probability increases
Solution Approach 1:
The patent applies preliminary action by requiring STAs to perform a backoff procedure before initiating frame exchanges after receiving group-addressed MPDUs. This backoff mechanism is executed in advance to randomize transmission timing and prevent simultaneous transmissions that would cause collisions, thereby maintaining reliable channel access while allowing multiple STAs to utilize the channel.
2Productivity
If a non-AP MLD allows multiple STAs to transmit simultaneously on different links, then throughput is improved, but interference between links occurs
Solution Approach 1:
The patent applies segmentation by dividing the multi-link device into multiple affiliated STAs, each responsible for specific link operations. The backoff procedure is applied at the individual STA level before frame exchange initiation, segmenting the transmission control to prevent simultaneous transmissions that would cause inter-link interference, while still allowing parallel operations across different links.
Solution Approach 2:
The patent applies local quality by implementing link-specific backoff procedures for each STA on each link. Instead of a uniform approach, each STA performs independent backoff calculations and transmissions are controlled locally at each link-STA combination, allowing optimized throughput while preventing harmful interference through localized transmission control.
3Loss of time
If frame exchanges are initiated immediately upon backoff timer expiration, then response time is improved, but overlap with frame reception on other links occurs
Solution Approach 1:
The patent applies feedback by implementing a mechanism where the non-AP MLD monitors frame reception status on all links before allowing frame exchanges to proceed. When a backoff timer expires for a STA, the system checks whether frame reception is occurring on other links and provides feedback to delay the frame exchange initiation if overlap is detected, ensuring reliable operation while minimizing time loss.
Data Source
AI summary
A first multi-link device (MLD) determines that there is an overlap between reception of one or more frames from a second MLD on a first link of a plurality of enhanced multi-link single-radio (EMLSR) links and a frame exchange with the second MLD on a second link of the plurality of EMLSR links in an event that the frame exchange is started upon either: (i) expiration of a backoff timer regarding the second link or (ii) receiving a soliciting frame regarding the second link. In response to the determining, the first MLD refrains from either: (i) initiating the frame exchange on the second link upon the expiration of the backoff timer (e.g., by deferring the frame exchange to a later time) responsive to the expiration of the backoff timer regarding the second link or (ii) transmitting a solicited frame on the second link responsive to receiving the soliciting frame.