Multi-link RTS CTS Collision Avoidance in Non-STR MLDs
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Solution Overview
Problem
In wireless local area networks (WLANs), the transmission of Clear to Send (CTS) frames during multi-link operations can lead to collisions, especially when non-Simultaneous Transmit and Receive (STR) Multi-Link Devices (MLDs) receive Request to Send (RTS) frames through different links, causing interference and reducing efficiency.
Innovation Solution
A method where a receiving Multi-Link Device (MLD) skips transmitting CTS frames when it is a Transmission Opportunity (TXOP) responder, allowing for efficient channel access by avoiding collisions between links, particularly in non-STR MLDs, by not transmitting CTS frames even if an RTS frame is received through other links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a receiving MLD transmits CTS frames in response to RTS frames received through different links, then channel access coordination is improved, but collisions occur between links in non-STR MLDs
Solution Approach 1:
The patent inverts the conventional RTS/CTS response behavior by having the receiving MLD send CTS frames back through the same link where the RTS was received, rather than through different links. This inversion prevents collisions in non-STR MLDs while maintaining channel access coordination, as the CTS transmission on the same link avoids interfering with other link operations.
2Reliability
If CTS frames are transmitted in multi-link operations, then acknowledgment of RTS is improved, but transmission efficiency decreases due to collisions
Solution Approach 1:
The patent applies local quality by making the CTS transmission behavior link-specific rather than uniform across all links. The receiving MLD determines whether to transmit CTS on each link based on local conditions (whether it's a TXOP holder on that link), allowing efficient channel access in some links while maintaining reliability in others, thus optimizing overall transmission efficiency.
3Adaptability or versatility
If non-STR MLD performs reception through some links, then link utilization is improved, but CTS transmission causes interference on other links
Solution Approach 1:
The patent segments the CTS transmission decision by link, allowing the non-STR MLD to independently control CTS transmissions on each link based on its reception status. This segmentation enables efficient utilization of available links for reception while preventing CTS transmissions on links where the MLD is actively receiving, thereby eliminating interference between links.
Data Source
AI summary
In a wireless local area network system. a reception multi-link device (MLD) may not transmit a CTS frame, even if the reception multi-link device receives an RTS frame via a second link, in the case that an STA operating via a first link is a TXOP responder.