Uplink Multi-User Sounding for WLAN Beamforming

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Solution Overview

Problem

Conventional beamforming schemes in Wireless Local-Area Networks (WLANs) face challenges with large bandwidth and numerous stations, as they require explicit Channel State Information (CSI) data transmission from client stations to the Access Point, leading to impractical bandwidth usage and overhead.

Innovation Solution

The method involves the Access Point requesting client stations to transmit channel-sounding packets, which are used to compute a beamforming matrix for directional transmissions, eliminating the need for explicit CSI data transmission and allowing concurrent beamforming across multiple stations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If explicit CSI data transmission is used from client stations to Access Point, then beamforming accuracy is improved, but bandwidth usage and overhead increase significantly

Engineering Contradiction:

Improvebeamforming accuracyVSAvoidbandwidth usage

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

Instead of having client stations transmit CSI data to the Access Point, the patent inverts the approach by having the Access Point transmit sounding packets and have client stations transmit received signal strength information back. This reversal eliminates the need for large CSI data transmissions while still enabling accurate beamforming through the computed beamforming matrix.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent extracts only the essential information needed for beamforming (received signal strength indicators from sounding packets) rather than transmitting complete CSI data sets. This extraction approach reduces the quantity of data transmitted while maintaining sufficient accuracy for beamforming operations.

Inventive Principle:

Principle #2Taking out (Extraction)

2Measurement precision

If explicit CSI data transmission is used from client stations to Access Point, then beamforming accuracy is improved, but overhead increases significantly

Engineering Contradiction:

Improvebeamforming accuracyVSAvoidoverhead

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent inverts the conventional approach by having the Access Point initiate the sounding process and transmit compact sounding packets, rather than having client stations transmit lengthy CSI reports. This inversion dramatically reduces overhead while maintaining beamforming accuracy through the simplified feedback mechanism.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent uses temporary sounding packets with minimal overhead that are discarded after use, rather than establishing persistent CSI data transmission channels. These disposable sounding packets reduce overall system overhead while providing sufficient information for beamforming calculations.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of operation

If conventional beamforming schemes are used, then beamforming functionality is achieved, but scalability to large bandwidths and numerous stations is poor

Engineering Contradiction:

Improvebeamforming functionalityVSAvoidscalability

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent inverts the conventional beamforming initialization approach by having the Access Point transmit sounding packets to multiple stations simultaneously rather than having each station transmit CSI reports sequentially. This inversion enables parallel processing and significantly improves scalability to large numbers of stations and bandwidths.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent merges multiple beamforming initialization operations into a single sounding packet transmission process. By combining the sounding packets for multiple stations into one transmission operation, the system achieves scalability while maintaining beamforming functionality across large bandwidths and numerous stations.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11711804B2Uplink multi-user sounding for WLAN

Publication Date: 2023.07.25 NXP USA INC

AI summary

A WLAN AP includes an array of antennas, a transceiver and a processor. The transceiver is configured to transmit via the array of antennas downlink packets to WLAN STAs, and to receive uplink packets from the STAs. The processor is coupled to the transceiver and is configured to send a request to a plurality of the STAs to transmit a respective plurality of channel-sounding packets corresponding to the plurality of STAs, to receive the plurality of channel-sounding packets from the plurality of STAs in response to the request, to compute, based on the received plurality of channel-sounding packets, a beamforming matrix that defines subsequent transmission beams aimed toward at least a subset of the plurality of STAs, and to transmit one or more downlink data packets to one or more of the STAs via the array of antennas, in accordance with the beamforming matrix.