UL MU-MIMO Precoding with Per-Station Feedback to Cut Interference
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently implementing beamforming techniques for uplink multi-user multiple-input multiple-output (UL MU-MIMO) communications due to high computational costs and interference issues, particularly in determining precoding coefficients for multiple stations.
Innovation Solution
A wireless access point (AP) transmits a first packet to trigger UL sounding packets from multiple stations, receives feedback, and provides per-station UL beamforming feedback using unitary precoder matrices, obtained through channel matrix projections and Givens rotation, to reduce computational overhead and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If per-station UL beamforming feedback is provided using unitary precoder matrices, then beamforming efficiency and reliability are improved, but computational complexity and feedback overhead increase
Solution Approach 1:
The patent transforms the channel matrix into a unitary precoder matrix through parameter transformations (QR decomposition and Givens rotations). This changes the representation of beamforming coefficients from raw channel measurements to unitary matrix parameters, improving beamforming reliability while controlling computational complexity through efficient parameter transformations.
Solution Approach 2:
The patent implements a feedback mechanism where the access point provides per-station UL beamforming feedback to wireless stations based on sounding packets. This feedback loop enables the stations to use unitary precoder matrices for beamforming, improving reliability through adaptive feedback while managing computational complexity through efficient feedback formats.
2Productivity
If multi-user beamforming is implemented, then communication speed and capacity are improved, but interference between stations increases
Solution Approach 1:
The patent segments the multi-user beamforming problem by providing separate per-station unitary precoder matrices to each wireless station. This segmentation allows independent beamforming control for each user, improving communication capacity through parallel transmissions while reducing inter-station interference through spatial separation and individual precoding.
Solution Approach 2:
The patent applies local quality by customizing beamforming parameters for each individual station based on its specific channel conditions. Each station receives per-station feedback with unitary precoder matrices tailored to its local channel characteristics, enabling optimized beamforming that improves capacity while minimizing interference specific to each user's spatial location.
3Ease of operation
If existing feedback formats are leveraged, then ease of operation is improved, but manufacturing precision and computational efficiency are reduced
Solution Approach 1:
The patent makes existing feedback formats universal by adapting them to serve dual purposes: traditional feedback functionality and new unitary precoder feedback. The per-station feedback format is designed to work with existing station capabilities while enabling enhanced beamforming, improving ease of operation through compatibility while maintaining computational efficiency through efficient feedback processing.
Data Source
AI summary
Various aspects relate generally to wireless communication and more particularly to beamforming techniques in wireless communication networks. Some aspects more specifically relate to beamforming techniques for uplink MU-MIMO communications, and the techniques can include UL MU-MIMO precoding using per-STA feedback. In some examples, an AP can support STA-side precoding for UL MU-MIMO communications by providing STAs with feedback representative of unitary matrices that correspond to block diagonal components of a matrix projection of channel matrices for the STAs in accordance with a linear equalizer. In some examples, the AP can trigger the STAs to transmit sounding packets concurrently, but can use the block diagonal matrix projection to process the various STAs' channels independently.