AMPDU Preemption via TRX Frame for Low Latency
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Solution Overview
Problem
Current wireless communication systems face delays in transmitting low-latency data due to the aggregation of multiple medium access control (MAC) service data units (MSDUs) into aggregated MAC protocol data units (AMPDUs), which can lead to undesirable delays in delay-sensitive data transmission.
Innovation Solution
The implementation of a trigger to receive (TRX) frame within an AMPDU to indicate preemption of non-low latency data, allowing for immediate acknowledgment of low-latency data and separate acknowledgement of non-low latency data, thereby enabling the transmission of low-latency data without waiting for completion of the AMPDU.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple MSDUs are aggregated into an AMPDU to reduce transmission overhead, then transmission efficiency is improved, but latency increases for delay-sensitive data
Solution Approach 1:
The patent segments the acknowledgment process into two distinct parts: immediate acknowledgment for low-latency data and deferred acknowledgment for non-low-latency data. This is achieved by inserting a Block Ack Request (BAR) frame within the AMPDU structure, allowing the receiver to send immediate ACKs for urgent frames while maintaining the aggregated transmission structure for overall efficiency.
Solution Approach 2:
The patent implements preliminary action by sending low-latency data frames within the AMPDU before the aggregated transmission completes, and immediately requesting acknowledgment via BAR frame. This allows critical data to be acknowledged and processed without waiting for the entire AMPDU to be transmitted and acknowledged, effectively preempting the acknowledgment sequence for time-sensitive data.
2Productivity
If the transmitter waits for AMPDU completion before sending another transmission, then aggregation overhead is reduced, but responsiveness to new low-latency data decreases
Solution Approach 1:
The transmitter performs preliminary action by inserting a BAR frame within the ongoing AMPDU transmission to solicit immediate acknowledgment for low-latency data. This allows the transmitter to maintain the aggregated transmission structure while simultaneously initiating the acknowledgment process for urgent data, enabling faster response without completing the entire AMPDU first.
Solution Approach 2:
The patent introduces dynamic behavior into the otherwise static AMPDU transmission process. By allowing mid-AMPDU acknowledgment requests and processing, the system becomes adaptable to time-varying latency requirements, enabling the transmission structure to flexibly accommodate both aggregated efficiency and immediate responsiveness based on data priority.
3Device complexity
If a single acknowledgment is sent after AMPDU completion, then acknowledgment overhead is reduced, but latency for individual low-latency frames increases
Solution Approach 1:
The patent segments the acknowledgment mechanism by introducing a Block Ack Request (BAR) frame that can be sent mid-AMPDU for specific low-latency frames. This creates separate acknowledgment streams: immediate BAR/ACK exchanges for urgent data and the final Block Ack for remaining frames, reducing the effective latency for time-sensitive data while maintaining aggregated transmission structure.
Solution Approach 2:
The BAR frame acts as an intermediary mechanism between the standard ACK and Block Ack processes. It enables selective immediate acknowledgment for low-latency frames within the aggregated AMPDU context, bridging the gap between individual frame urgency and aggregated transmission efficiency without requiring complete AMPDU completion.
Data Source
AI summary
Systems, methods, and mechanisms for preemption of non-low latency data within an aggregated medium access control (MAC) protocol data unit (AMPDU), e.g., such as in current and future IEEE 802.11 systems. A wireless device (e.g., an access point or wireless station) may transmit, during an AMPDU, a trigger to receive (TRX) frame. The TRX frame may indicate preemption of non-low latency data intended for a first wireless station with low latency data intended for a second wireless station, e.g., via an acknowledgement policy change. Additionally, the wireless device may be configured to transmit, to the second wireless station, the low latency data within the AMPDU. Further, the wireless device may be configured to receive, after the AMPDU transmission is complete, a multi-block acknowledgement (M-BA) frame from the second wireless station. The M-BA frame and completion of the AMPDU transmission are separated by a short inter-frame space (SIFS).