Differential Beamforming Feedback Matrix Encoding
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Solution Overview
Problem
Next-generation wireless local area networks (WLANs) face challenges in efficiently transmitting and receiving feedback frames for beamforming matrices, particularly in high-dimensional scenarios, leading to increased feedback overhead and transmission time due to the large quantity of data required for accurate beamforming feedback.
Innovation Solution
A differential feedback method is proposed, where the difference in quantized values between adjacent subcarriers is fed back, reducing the number of feedback bits and transmission time by only transmitting the differences in index values of quantized phi and psi between subcarriers, rather than the full values for each subcarrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full beamforming feedback matrix is transmitted for each subcarrier, then beamforming accuracy is improved, but feedback overhead and transmission time increase significantly
Solution Approach 1:
The feedback matrix for each subcarrier is segmented into two parts: a common part (first matrix) that is identical across all subcarriers, and a differential part (second matrix) that contains only the differences between adjacent subcarriers. This segmentation allows the receiver to reconstruct the full feedback information by combining the common part with the differential parts, significantly reducing the total feedback overhead while maintaining beamforming accuracy.
Solution Approach 2:
Instead of transmitting complete feedback matrices for every subcarrier, the patent transmits only the essential differential information that captures the variations between adjacent subcarriers. This partial action approach is sufficient because the common part is already known to the transmitter, and the differential parts provide the necessary corrections to achieve accurate beamforming without the excessive overhead of full matrix transmission.
2Quantity of substance
If differential feedback method is used, then feedback overhead is reduced, but feedback information completeness may be compromised
Solution Approach 1:
The transmitter first sends a null data packet announcement (NDPA) frame followed by a null data packet (NDP) frame that contains the common feedback matrix information before the actual data transmission. This preliminary action ensures that both transmitter and receiver have the common part information available, so that when the differential feedback is transmitted later, the complete information can be reconstructed without loss.
Solution Approach 2:
The patent implements a feedback mechanism where the receiver calculates the differential feedback matrices by comparing the channel state information with the common feedback matrix, and then feeds back only these differential parts to the transmitter. The transmitter uses this feedback along with the pre-transmitted common part to reconstruct the complete beamforming information, ensuring information completeness while minimizing feedback overhead.
Data Source
AI summary
Proposed are a method and device for receiving a feedback frame in a wireless LAN system. Specifically, a first STA transmits an NDPA frame to a second STA. The first STA transmits an NDP frame to the second STA. The first STA receives, from the second STA, a feedback frame transmitted on the basis of the NDP frame. The feedback frame includes information about a beamforming feedback matrix. The information about the beamforming feedback matrix includes a first bit for the index difference between quantized phi of adjacent subcarriers, and a second bit for the index difference between quantized psi of the adjacent subcarriers. The adjacent subcarriers are two adjacent subcarriers starting with the first subcarrier among all of the subcarriers. The first subcarrier is either the left edge subcarrier or the right edge subcarrier. The quantized phi and psi are information about beamforming angles.