Multi-AP Channel Sounding with Centralized CSI Feedback

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Solution Overview

Problem

Existing WLAN systems face challenges in efficiently coordinating channel sounding procedures across multiple access points (APs), leading to suboptimal performance and resource utilization.

Innovation Solution

The method involves a multi-AP channel sounding procedure for WLAN systems, which includes a method for a station (STA) associated with a first access point (AP) to receive a null data packet announcement (NDPA) frame from a second AP, transmit feedback based on the NDP frame, and participate in a multi-AP channel sounding procedure, utilizing a Special STA Info field to indicate the number of APs and STAs involved.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multi-AP channel sounding is implemented, then channel measurement efficiency is improved, but coordination complexity between APs increases

Engineering Contradiction:

Improvechannel measurement efficiencyVSAvoidcoordination complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent introduces a leading AP as an intermediary that coordinates the multi-AP channel sounding procedure. The leading AP receives NDP feedback from STAs and distributes it to other APs in the MAP set, simplifying the coordination complexity by centralizing the management of channel state information collection across multiple APs

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the multi-AP channel sounding procedure into distinct phases: NDP transmission phase, feedback collection phase, and feedback distribution phase. This segmentation allows each AP to perform specific functions at appropriate times, improving channel measurement efficiency while managing coordination complexity through structured procedural division

Inventive Principle:

Principle #1Segmentation

2Loss of information

If feedback is transmitted to all APs in MAP set, then channel state information availability is improved, but overhead increases

Engineering Contradiction:

Improvechannel state information availabilityVSAvoidfeedback overhead

Core Design Contradiction:

Loss of informationVSQuantity of substance

Solution Approach 1:

The patent merges the feedback distribution function into a unified process where the leading AP consolidates NDP feedback from multiple STAs and distributes the combined information to all APs in the MAP set. This approach ensures all APs receive comprehensive channel state information while reducing redundant feedback transmissions, thereby managing overhead efficiently

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The leading AP performs multiple functions: receiving NDP frames from STAs, processing the feedback information, and distributing it to other APs. This multi-functionality reduces the need for separate dedicated feedback mechanisms for each AP pair, improving channel state information availability while controlling overhead through consolidated processing

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12634058B2Multi-AP channel sounding procedures for WLAN systems

Publication Date: 2026.05.19 INTERDIGITAL PATENT HOLDINGS INC

AI summary

A method performed by a station (STA) associated with a first access point (AP), wherein the first AP is part of a multi-AP (MAP) set comprising the first AP and at least a second AP, may compromise: receiving, from the second AP that the STA is not associated with, a null data packet announcement (NDPA) frame, the NDPA frame including a Special STA Info field including an association identifier (AID) relating to the association between the STA and the first AP; receiving a null data packet (NDP) frame from the second AP that the STA is not associated with; and transmitting, to the first AP, feedback based on the NDP frame.