WLAN Channel Sounding With Smoothed Beamforming Feedback
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Solution Overview
Problem
In wireless communication systems, particularly in MU-MIMO environments, beamforming processes lead to discontinuity between beamforming matrices corresponding to adjacent subcarriers, resulting in energy loss and increased packet error rates due to the absence of channel smoothing operations on beamformed signals.
Innovation Solution
Implementing a method where a first apparatus transmits a null data packet (NDP) to a second apparatus, allowing the second apparatus to estimate a channel and generate channel smoothing-related phase information, which is then fed back to the first apparatus for reducing discontinuity in beamforming matrices, thereby enabling efficient channel smoothing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If beamforming process is performed without channel smoothing operation, then beamforming can be implemented, but discontinuity between beamforming matrices occurs resulting in energy loss and increased packet error rate
Solution Approach 1:
The patent applies preliminary action by performing channel smoothing operation before beamforming matrix generation. The beamformee smooths the estimated channel response across adjacent subcarriers prior to computing beamforming matrices, ensuring continuity is established in advance. This prevents discontinuity-related energy loss during subsequent beamforming operations without requiring complex real-time adjustments.
Solution Approach 2:
The patent implements feedback by having the beamformee transmit smoothed channel information back to the beamformer. The beamformee performs channel smoothing on the estimated channel and feeds back the smoothed channel response, enabling the beamformer to generate continuous beamforming matrices. This feedback mechanism ensures beamforming matrix continuity while maintaining relatively simple device operations.
2Reliability
If channel smoothing operation is performed on beamformed signal, then discontinuity between beamforming matrices can be reduced, but beamformee cannot perform smoothing due to existing protocol limitations
Solution Approach 1:
The patent applies inversion by reversing the traditional beamforming workflow. Instead of the beamformer performing smoothing (which would require protocol changes), the beamformee performs the channel smoothing operation on the estimated channel before feedback. This role reversal enables discontinuity reduction while maintaining compatibility with existing 802.11ac/ax protocols, as the beamformee already has access to the raw channel estimates needed for smoothing.
Solution Approach 2:
The patent introduces smoothed channel information as an intermediary between channel estimation and beamforming matrix generation. The beamformee acts as an intermediary by smoothing the estimated channel response and providing the smoothed version to the beamformer. This intermediary smoothed channel enables the beamformer to generate continuous beamforming matrices without requiring the beamformee to perform complex real-time smoothing operations on transmitted signals.
Data Source
AI summary
An operation method of a first apparatus configured to communicate with a second apparatus in a wireless local area network (WLAN) system including the first apparatus and the second apparatus includes receiving, from the second apparatus, a null data packet (NDP) based on a certain protocol standard, estimating a channel with the second apparatus on the basis of the NDP, determining, on the basis of the estimated channel, whether or not a channel smoothing-related condition is satisfied, generating channel smoothing-related phase information on the basis of a result of the determination, and transmitting, to the second apparatus, a feedback frame including the channel smoothing-related phase information.