Multi-Link Frame Alignment for WLAN Medium State Synchronization
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Solution Overview
Problem
Wireless local area network (WLAN) devices with multiple radios and media access control functions experience interference coupling during transmission, leading to drops in system throughput and performance due to simultaneous transmit and receive operations on multiple wireless links, causing deafness on one link and loss of medium state synchronization.
Innovation Solution
Implement mechanisms to align transmissions on different wireless links by initiating data units, requesting triggers, and synchronizing end times of response transmissions, ensuring correct medium state determination and maintaining system MAC synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If simultaneous transmit and receive operation is performed on multiple wireless links, then system throughput is improved, but medium state synchronization is lost and performance drops due to interference coupling
Solution Approach 1:
The patent segments the wireless communication operations by introducing alignment indicators that divide the transmission timeline into synchronized segments. Each link's transmissions are segmented to align with a reference link, preventing interference coupling while maintaining overall system productivity through coordinated multi-link operation.
Solution Approach 2:
The patent implements feedback mechanisms where alignment indicators are exchanged between devices to maintain medium state synchronization. The receiving device sends feedback about its medium state and alignment status, allowing the transmitting device to adjust its transmissions to maintain synchronization while operating on multiple links simultaneously.
2Reliability
If transmissions are aligned across multiple wireless links, then medium state synchronization is maintained, but transmission flexibility and adaptability are reduced
Solution Approach 1:
The patent introduces dynamic alignment indicators that can be adjusted on a per-transmission basis. Rather than rigidly fixing all transmissions to identical timing, the alignment indicators allow dynamic adjustment of transmission timing while maintaining synchronization, preserving adaptability for different traffic conditions and channel states.
Solution Approach 2:
The patent changes the parameter of transmission timing by introducing alignment indicators that specify relative timing offsets. This allows the system to maintain synchronization through controlled parameter changes rather than fixed rigid timing, enabling adaptability while preserving medium state synchronization.
3Reliability
If trigger frames are used to request transmissions on multiple links, then coordination is improved, but device complexity and protocol overhead increase
Solution Approach 1:
The patent makes the trigger frame multi-functional by incorporating alignment indicators that serve both as transmission triggers and as synchronization coordination signals. This single frame structure performs multiple functions (triggering transmission and maintaining alignment) rather than requiring separate frames for each function, reducing protocol overhead while improving coordination.
Solution Approach 2:
The patent merges the trigger function and alignment indication function into a single integrated frame structure. Rather than using separate trigger frames and alignment negotiation sequences, the alignment indicators are embedded within the trigger frame itself, combining multiple coordination functions into one message to reduce overhead and device complexity.
Data Source
AI summary
A multi-link device may be configured to initiate transmission of a first data unit on a first wireless link of a first multi-link device, and request transmission of a trigger from a second multi-link device on a second wireless link. In response to receiving the trigger, the multi-link device may align a last symbol end time of a response transmission on the second wireless link with a last symbol end time of the first data unit being transmitted on the first multi-link device.