NSTR Multi-Link Control Frames for Medium Sync Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communications, multi-link devices operating on a non-simultaneous-transmission-and-reception link pair face issues with medium synchronization due to in-device coexistence interference, leading to collisions and loss of synchronization, particularly when one link is transmitting a PPDU with a length greater than a threshold, affecting the network allocation vector update and medium access recovery.
Innovation Solution
Proposed schemes involve transmitting a control frame with a medium sync lost indication as an initial frame of a TXOP, using modified CCA-ED thresholds for channel access, and resetting MediumSyncDelay timers based on synchronization status to facilitate medium access recovery for peer multi-link devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an NSTR MLD transmits on link 1, then transmission completes successfully, but the MLD cannot listen to transmissions on link 2 and update NAV due to interference from transmit power leakage
Solution Approach 1:
The patent applies preliminary action by having the TXOP initiator send a control frame (RTS) before the actual data transmission. This control frame carries information about the intended transmission, allowing the receiver to prepare for medium access recovery before the main transmission occurs. The control frame is transmitted when the MediumSyncDelay timer is non-zero, enabling proactive synchronization recovery rather than reactive correction after collision occurs.
Solution Approach 2:
The patent implements feedback through the control frame exchange mechanism. The TXOP initiator sends a control frame indicating medium sync loss status, and the TXOP responder responds with a control response frame. This feedback loop allows both devices to synchronize their medium access recovery processes, ensuring that the receiver is properly synchronized before data transmission begins, thus preventing collisions.
2Loss of time
If the MediumSyncDelay timer is non-zero, then medium synchronization is lost, but the device cannot properly access the medium without updated NAV information
Solution Approach 1:
The patent enables medium access recovery by performing preliminary actions before the actual data transmission. The TXOP initiator sends a control frame when the MediumSyncDelay timer is non-zero, initiating the synchronization recovery process in advance. This allows the device to regain medium access capability without waiting for the timer to expire naturally, reducing the loss of time while maintaining ease of operation.
Solution Approach 2:
The control frame acts as an intermediary mechanism between the TXOP initiator and responder. It carries information about the medium sync loss status and enables coordination during the recovery period. This intermediary allows devices to navigate the synchronization delay period smoothly, maintaining operational ease while addressing the time loss issue.
3Reliability
If virtual channel sensing is not feasible during blindness period, then collision may occur on link 2, but the device cannot detect ongoing transmissions without updated NAV
Solution Approach 1:
The patent applies preliminary action by having the TXOP initiator send a control frame before the data transmission begins. This control frame is received by the TXOP responder even when the MediumSyncDelay timer is non-zero, allowing the responder to update its NAV and synchronize before the main transmission occurs. This prevents collisions by ensuring medium access information is available in advance, making transmission detection feasible without waiting for the blindness period to end.
4Productivity
If an NSTR AP MLD transmits on primary link alone, then downlink transmission completes, but the non-primary link STA loses medium synchronization and cannot initiate TXOP
Solution Approach 1:
The patent applies preliminary action by having the TXOP initiator send a control frame before data transmission on the non-primary link. This control frame is transmitted when the MediumSyncDelay timer is non-zero, initiating the synchronization recovery process in advance. This allows the non-primary link STA to regain medium synchronization before attempting to initiate a TXOP, ensuring reliable operation while maintaining downlink transmission productivity.
Data Source
AI summary
A station (STA) affiliated with a non-simultaneous-transmission-and-reception (NSTR) multi-link device (MLD) obtains a transmission opportunity (TXOP) on a first link of an NSTR link pair as a TXOP initiator while a medium synchronization delay timer of the STA is non-zero. STA determines that an intended TXOP responder has lost medium synchronization. The STA then transmits a control frame as an initial frame in the TXOP to the intended TXOP responder on the first link responsive to the determining.