MU-MIMO Precoding Vector Index Feedback for WLAN Throughput
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Solution Overview
Problem
In wireless local area networks (WLAN) using multi-channels and multi-user multi-input multi-output (MU-MIMO) methods, the large amount of feedback information required for channel state and beamforming matrices hinders throughput improvement.
Innovation Solution
The method involves an access point and station sharing precoding vector information, where the station transmits index information of a preferred precoding vector and channel quality information, allowing the access point to perform precoding operations without needing the full beamforming vector feedback, thereby reducing feedback information and improving throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the station feeds back channel state information matrix or beamforming matrix for MU-MIMO, then the access point can perform precoding operation, but the amount of feedback information becomes comparatively large
Solution Approach 1:
The patent extracts only the essential information needed for precoding by having the station feed back index information indicating a selected precoding vector from a predetermined codebook, rather than feeding back the entire channel state information matrix or beamforming matrix. This extraction principle reduces feedback overhead while maintaining sufficient accuracy for precoding operations at the access point.
Solution Approach 2:
The patent uses a codebook approach where the access point and station share predetermined precoding vectors. Instead of transmitting full channel state information, the station selects and feeds back an index to a precoding vector that best matches the current channel conditions. The access point then uses the corresponding precoding vector from its local copy of the codebook, achieving accurate precoding with minimal feedback.
2Productivity
If multi-channel is used in MU-MIMO, then throughput can be improved, but the amount of feedback information increases as much as the number of multi-channels
Solution Approach 1:
The patent segments the feedback information requirement by channel, allowing the station to select and feed back a precoding vector index for each channel independently. This segmentation enables the system to take advantage of multi-channel diversity for improved throughput while keeping the feedback amount manageable by only transmitting indices rather than full channel state information for each channel.
Solution Approach 2:
The patent changes the parameter being fed back from full channel state information matrices to compact index values that reference predetermined precoding vectors. This parameter transformation maintains the ability to adapt to multi-channel conditions for throughput improvement while dramatically reducing the amount of feedback information required.
3Measurement precision
If the station feeds back full beamforming vector information, then the access point can perform accurate precoding, but the feedback overhead increases significantly
Solution Approach 1:
The patent extracts only the essential directional information needed for beamforming by having the station select a precoding vector from a codebook that captures the dominant spatial characteristics of the channel. The station feeds back only the index of the selected vector, extracting the most important beamforming information while discarding redundant details, thus reducing feedback overhead while maintaining adequate precision for accurate precoding.
Data Source
AI summary
A MU-MIMO method of an access point in a WLAN using multi-channels and having at least one station includes: receiving index information indicating a precoding vector for a beam selected by the station and channel quality information thereof for each one of the multi-channels; generating first channel capacity information of channel combination groups using the channel quality information wherein the channel combination groups are grouped according to a predetermined channel bandwidth of the multi-channels; and allocating resources to the station from a channel combination selected from the channel combination groups according to the first channel capacity information using the index information and the channel quality information, wherein the access point and the station previously store precoding vector information for a plurality of beams for the MU-MIMO.