Triggered Sounding NDP for Uplink Beamforming
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Solution Overview
Problem
Current Wi-Fi standards, such as 802.11ax, lack a suitable format for using triggered transmissions for uplink beamforming (UL BF), which is essential for improving signal-to-noise ratio and transmission speed in multiple-input multiple-output (MIMO) scenarios.
Innovation Solution
The proposed solution involves setting the transmit parameters of a trigger-based physical protocol data unit (PPDU) by the access point (AP) for a triggered sounding null data packet (NDP) in uplink, using either a trigger-based (TB) PPDU or an Extremely High Throughput (EHT) multi-user (MU) PPDU without a payload, and incorporating parameters in the universal signal (U-SIG) section to indicate a triggered NDP transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a suitable format for triggered transmissions is not defined in existing protocols, then uplink beamforming cannot be properly implemented, but defining a new format increases protocol complexity
Solution Approach 1:
The patent reuses existing PPDU frame structures (TB PPDU and EHT MU PPDU) for triggered sounding NDP transmissions, allowing these frames to serve both traditional data transmission functions and new beamforming sounding functions. The U-SIG section is enhanced to include parameters that indicate triggered NDP transmission, enabling the same frame format to handle multiple functions without requiring entirely new protocol structures.
Solution Approach 2:
The patent modifies existing frame parameters by adding specific indicators in the U-SIG section to denote triggered NDP transmission. This allows the system to distinguish between regular transmissions and beamforming sounding transmissions using parameter changes rather than structural changes, maintaining protocol simplicity while enabling new functionality.
2Measurement precision
If all stations transmit the same preamble contents for triggered sounding, then channel estimation accuracy improves, but transmission flexibility decreases
Solution Approach 1:
The patent specifies that certain fields in the PPDU frame (such as the preamble) should contain identical content across all triggered stations to ensure accurate channel estimation at the AP. Meanwhile, other fields can vary to maintain transmission flexibility. This local uniformity approach ensures that the critical sounding portion is standardized while allowing flexibility in other transmission aspects.
3Measurement precision
If the AP sets transmit parameters for triggered sounding NDP, then uplink beamforming accuracy improves, but station autonomy decreases
Solution Approach 1:
The patent introduces a trigger frame as an intermediary mechanism that carries AP's transmit parameter settings for the upcoming triggered sounding NDP transmission. The trigger frame acts as a mediator between the AP's beamforming requirements and the STA's transmission execution, allowing the AP to precisely control beamforming parameters while maintaining a clear separation of responsibilities in the protocol flow.
Data Source
AI summary
A method of uplink sounding signal triggering, performed by an access point (AP), comprises the steps of transmitting, by the AP, a triggering signal to one or more stations (STAs), triggering transmission of a respective sounding signal from at least one STA of the one or more STAs in response to the triggering signal; receiving, by the AP, the respective sounding signal from the at least one STA; and determining, by the AP, a precoder to be used by the at least one STA based on the respective sounding signal, and transmitting corresponding precoder information to the at least one STA for data transmission, wherein the triggering signal comprises a null data packet announcement (NDPA) signal or a null data packet request (NDPR) signal and the sounding signal comprises a triggered sounding null data packet (NDP) signal.