Fast BA Feedback for WLAN Link Adaptation Under SINR Changes
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Solution Overview
Problem
Current link adaptation algorithms in wireless communication systems, particularly in IEEE 802.11, struggle to track fast and varying signal-to-interference-plus-noise ratio (SINR) changes, leading to throughput loss and increased power consumption due to inefficient modulation and coding scheme selection, especially with bursty interference and varying channel conditions.
Innovation Solution
Implementing a fast feedback protocol in block acknowledgments (BAs) to provide immediate or solicited feedback on per-stream SINR, allowing devices to adjust modulation and coding schemes more effectively, and negotiating feedback protocols to enhance processing time and trust between transmitting and receiving devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional link adaptation algorithms are used, then device complexity is reduced, but throughput is lost due to inability to track fast SINR changes
Solution Approach 1:
The patent implements a fast feedback mechanism where the receiver immediately feeds back per-stream SINR measurements to the transmitter after receiving each PPDU. This feedback loop enables the transmitter to dynamically adjust MCS selection based on real-time channel conditions, resolving the contradiction by achieving high throughput through continuous adaptation while managing complexity through structured feedback protocols
Solution Approach 2:
The system dynamically adjusts the modulation and coding scheme based on real-time SINR measurements and feedback. The link adaptation algorithm transitions from static pre-configured rates to dynamic per-stream MCS selection, allowing the system to adapt to fast-changing channel conditions and maximize throughput under varying interference patterns
2Productivity
If link adaptation algorithms are used, then throughput is improved, but power consumption increases due to inefficient MCS selection
Solution Approach 1:
The immediate feedback of per-stream SINR measurements enables the transmitter to select optimal MCS rates that match actual channel conditions. This prevents using overly conservative rates that waste energy and avoids retransmissions that consume additional power, thereby reducing overall energy consumption while maintaining high throughput
Solution Approach 2:
The system changes the MCS parameters (modulation order, coding rate) based on real-time SINR measurements. By dynamically adjusting these parameters to match actual channel conditions rather than using fixed or conservative settings, the system optimizes the energy-efficiency trade-off and reduces power consumption while maintaining throughput
3Productivity
If fast feedback is implemented, then link adaptation is enhanced, but processing time is reduced for feedback transmission
Solution Approach 1:
The patent extracts only the essential feedback information (per-stream SINR measurements) from the full PPDU reception process and transmits only this critical data back to the transmitter. This selective feedback approach maintains fast adaptation performance while minimizing the time required for feedback transmission and processing
Solution Approach 2:
The receiver performs SINR measurements and prepares feedback information immediately after PPDU reception, before any potential retransmission or next transmission cycle begins. This preliminary feedback preparation eliminates processing delays and ensures the transmitter receives accurate channel state information in time for immediate MCS adjustment
Data Source
AI summary
This disclosure relates to methods for link adaptation with fast feedback in a wireless local area network. A wireless device can receive a physical protocol data unit (PPDU), e.g., from another wireless device such as from an access point. The wireless device can transmit a block acknowledgment (BA) frame that includes fast feedback information to the other wireless device. The BA frame that includes fast feedback information can be transmitted in an unsolicited or solicited manner and/or can be transmitted after a negotiation with the other wireless device to include fast feedback information in the BA frame. Fast feedback information can include at least a per stream effective signal to interference plus noise ratio (SINR) or SINR margin.