WLAN Channel Sounding With NDP Requests for Consistent Channel Tracking
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Solution Overview
Problem
Existing WLAN sensing technologies face limitations in obtaining regular periodicity and performance in channel estimation due to overhead and the use of compressed beamforming feedback, particularly in tracking channel variations caused by motion and transmitter settings changes.
Innovation Solution
A novel WLAN sensing protocol utilizing null data packets (NDPs) with a request-and-response mechanism, where the responding station transmits NDPs with consistent transmit parameters, ensuring consistent spatial mapping matrices and periodicity, and supports multiple NDP transmissions for enhanced channel tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If compressed beamforming feedback is used for channel estimation, then device complexity is reduced, but measurement precision deteriorates due to overhead and inability to track channel variations accurately
Solution Approach 1:
The patent extracts the channel sounding function from the data transmission protocol by introducing dedicated Null Data Packets (NDPs). These NDPs are specifically designed for channel estimation purposes, separating the measurement function from regular data communication. This allows accurate channel tracking without the overhead and compression limitations of beamforming feedback mechanisms.
Solution Approach 2:
The patent implements preliminary channel sounding by transmitting NDPs before actual data transmission. The channel characteristics are measured in advance using these dedicated packets, allowing the system to prepare channel state information (CSI) and feedback matrices beforehand. This preliminary measurement enables more accurate and timely channel estimation compared to reactive beamforming feedback.
2Measurement precision
If regular periodic channel estimation is implemented, then measurement precision improves for tracking motion, but productivity deteriorates due to overhead from multiple transmissions
Solution Approach 1:
The patent merges channel sounding with the existing data transmission framework by utilizing the same physical layer protocol structures. NDPs are integrated into the MAC layer framework, allowing channel estimation to occur within the existing communication rhythm rather than as separate overhead transmissions. This combining approach enables periodic channel tracking while maintaining overall system productivity.
3Measurement precision
If multiple NDP transmissions are supported for enhanced channel tracking, then measurement precision improves, but device complexity increases due to parameter management
Solution Approach 1:
The patent implements feedback mechanisms where receiving stations send channel state information (CSI) and feedback matrices back to transmitting stations based on received NDPs. This feedback loop enables iterative refinement of channel estimates across multiple transmissions. The feedback process is standardized through defined matrix structures and compression techniques, managing complexity through systematic information exchange rather than ad-hoc parameter management.
Data Source
AI summary
This disclosure describes systems, methods, and devices related to WLAN sensing sounding. A device may identify a sensing null data packet (NDP) request frame received from a second device, the sensing NDP request frame associated with performing a wireless local area network channel sounding procedure; identify transmit parameters included in a transmit control field of the sensing NDP request frame; generate an NDP frame using the transmit parameters; and send, in response to the sensing NDP request frame, the NDP frame to the second device.