Multi-AP OBSS Sounding Signaling Using Triggered NDP Feedback
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Solution Overview
Problem
Existing wireless LAN systems face challenges in efficiently performing an OBSS (overlapping basic service set) sounding procedure, which is crucial for multi-access point operations to enhance communication efficiency and reliability.
Innovation Solution
A method and device for performing an OBSS sounding procedure through the exchange of NDP announcement frames and feedback frames between stations and access points, enabling efficient measurement operations and multi-access point coordination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional single AP sounding procedure is used, then the procedure is simple to implement, but multi-access point coordination and communication efficiency are limited
Solution Approach 1:
The patent combines multiple access points into a coordinated system where multiple APs jointly perform the sounding procedure. The trigger frame includes information about multiple APs (first AP and second AP) that will participate in the sounding, allowing STAs to receive signals from multiple APs simultaneously and report combined channel state information, thereby improving communication efficiency in multi-AP environments
Solution Approach 2:
The patent introduces a trigger frame as an intermediary mechanism that coordinates the sounding procedure between multiple APs and STAs. The trigger frame contains trigger information that instructs STAs to receive NDP frames from specific APs and report feedback, serving as a mediator that enables complex multi-AP coordination without requiring direct complex interactions between all APs and STAs
2Measurement precision
If OBSS sounding procedure is performed without multiple AP coordination, then the procedure is simpler, but channel state information acquisition between BSS and OBSS is insufficient
Solution Approach 1:
The patent merges the sounding procedures of multiple APs into a single coordinated OBSS sounding procedure. The trigger frame includes information about both the first AP (in the same BSS) and the second AP (in a different BSS), allowing the STA to receive NDP frames from both APs and report combined channel state information, thereby improving measurement precision for inter-BSS communication
Solution Approach 2:
The patent implements a feedback mechanism where the STA reports channel state information for both the first AP and the second AP back to the first AP. This feedback includes feedback frames that contain measurement results for both APs, enabling the system to accurately characterize the channel conditions between BSS and OBSS based on the received feedback
3Productivity
If NDP frames are transmitted without coordinated trigger information, then transmission is simpler, but multi-access point operation efficiency is reduced
Solution Approach 1:
The patent applies preliminary action by having the first AP transmit a trigger frame before the actual NDP frame transmission. The trigger frame includes trigger information that prepares the STA for the upcoming sounding procedure, instructing it to expect NDP frames from both the first AP and the second AP, and to report feedback accordingly. This preliminary coordination enables efficient multi-AP operation without complicating the actual signal transmission
Data Source
AI summary
A method and a device for operating in a wireless LAN system are disclosed. A method performed by a first STA in a wireless LAN system, according to one embodiment of the present disclosure, comprises the steps of: receiving, from a first AP, a first NDP null data physical protocol data unit (PPUD) announcement frame; receiving the NDP frame from the first AP on the basis of the NDP announcement frame; and transmitting, to a second AP, a feedback frame for the NDP frame, wherein the NDP announcement frame can be transmitted to the first STA on the basis of trigger information transmitted from the second AP.