Multi-Link Trigger Frame Scheduling for Wireless Interference Mitigation
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Solution Overview
Problem
In wireless communication systems, multi-link operations face significant performance loss due to in-device coexistence interference (IDC) when devices transmit and receive data simultaneously over different frequency bands, particularly between the 5 GHz and 6 GHz bands, making it difficult to synchronize transmissions to avoid interference.
Innovation Solution
The method involves transmitting trigger frames with a carrier sense (CS) required field over one wireless link and ensuring that responses are sent only after the completion of the trigger frame transmission on another link, with a predetermined time margin to prevent simultaneous transmission and reception, using techniques like MAC padding, PHY padding, or packet extension to adjust the ending times of protocol data units (PPDUs).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multi-link operation is used to increase bandwidth, then communication bandwidth is improved, but in-device coexistence interference occurs causing performance loss and packet loss
Solution Approach 1:
The patent applies preliminary action by having the AP transmit a trigger frame that schedules future TB PPDU transmissions in advance. The trigger frame includes a Scheduling Information field that specifies the timing and resource allocation for upcoming transmissions, allowing the device to prepare and align its transmission schedule before actual data transmission occurs, thereby preventing IDC interference through proactive timing coordination
Solution Approach 2:
The patent implements dynamics by making the TB PPDU transmission timing flexible and adjustable based on trigger frame scheduling. The transmission time is not fixed but dynamically determined by the AP's trigger frames, allowing the system to adapt transmission schedules across multiple links to avoid simultaneous transmission and reception, thus resolving the bandwidth-reliability contradiction
2Productivity
If simultaneous transmission and reception over multiple bands is performed, then communication efficiency is improved, but IDC interference substantially impacts performance
Solution Approach 1:
The patent applies segmentation by dividing the communication process into distinct phases: trigger frame reception phase and TB PPDU transmission phase. The trigger frame is received on one link while the TB PPDU transmission is scheduled for a different time on another link, segmenting the simultaneous transmission and reception operations into sequential phases that avoid interference while maintaining multi-link efficiency
Solution Approach 2:
The trigger frame acts as an intermediary that mediates between the AP's scheduling decisions and the device's transmission actions. It carries scheduling information that coordinates timing across multiple links, serving as a control mechanism that enables efficient multi-link operation while preventing IDC interference through centralized scheduling
3Adaptability or versatility
If trigger frames are transmitted without scheduling coordination, then transmission flexibility is maintained, but synchronization difficulty prevents avoidance of simultaneous transmission and reception
Solution Approach 1:
The trigger frame performs preliminary scheduling action by specifying future transmission times in the Scheduling Information field. This allows the receiving device to know in advance when TB PPDU transmissions will occur on different links, enabling it to align its reception and transmission operations to avoid simultaneous operations without requiring complex real-time synchronization mechanisms
Solution Approach 2:
The system implements feedback through the trigger frame mechanism, where the AP monitors channel conditions and device status, then provides scheduling instructions in subsequent trigger frames. This closed-loop control maintains transmission flexibility while managing synchronization complexity by allowing the AP to adjust schedules based on observed interference patterns and channel states
Data Source
AI summary
Embodiments of the present invention prevent interference caused by the simultaneous transmission and reception of data in a constrained multi-link operation of a wireless network. According to one embodiment, a frame from a first affiliated AP of a multi-band wireless AP is transmitted for receipt by an STA, and a second affiliated wireless AP of the multi-band wireless AP is scheduled to transmit a trigger frame to the wireless STA over a second wireless link. Accordingly, the trigger frame is transmitted from the second affiliated wireless AP to the wireless STA over the second wireless link, and the response frame solicited by the frame is scheduled for transmission after the predetermined value has expired following an end of the PPDUs containing the trigger frame.