Multi-AP Channel Sounding with Implicit Feedback
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Solution Overview
Problem
Current wireless communication systems face inefficiencies in high-density deployment environments due to high overhead and latency in channel state information feedback, especially with increasing numbers of antennas and spatial streams, leading to inaccurate beamforming weights and increased interference.
Innovation Solution
The implementation of an enhanced channel sounding system that includes a polling phase for implicit channel sounding, time and spatial multiplexing of NDPs, and time domain compressed feedback to reduce overhead and latency, allowing for direct calculation of beamforming weights and improved scheduling of STAs based on RSSI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If explicit channel state information feedback is used with increasing numbers of antennas and spatial streams, then beamforming accuracy can be improved, but network overhead and latency increase significantly
Solution Approach 1:
The patent extracts only the essential channel information needed for beamforming by using implicit feedback mechanisms. Instead of transmitting complete channel state information matrices, the system extracts and feeds back only the necessary components (such as beamforming weights or compressed channel representations), significantly reducing feedback overhead while maintaining beamforming accuracy.
Solution Approach 2:
The patent transforms the channel state information from its original high-dimensional form into a compressed representation with fewer parameters. By changing the parameter space (e.g., using singular value decomposition to keep only dominant singular values, or using codebook-based quantization), the system reduces feedback dimensionality while preserving the most important channel characteristics for beamforming.
2Measurement precision
If complete channel state information is fed back to calculate beamforming weights, then beamforming precision is improved, but latency increases due to feedback transmission time
Solution Approach 1:
The patent extracts only the critical channel components needed for timely beamforming weight calculation. By using implicit feedback where stations transmit compressed channel representations or direct beamforming weight suggestions, the system reduces feedback transmission time while maintaining sufficient precision for accurate beamforming.
Solution Approach 2:
The patent uses partial channel state information feedback instead of complete feedback. By transmitting only the most significant channel components (e.g., top K singular values, or quantized beamforming vectors from a codebook), the system achieves acceptable beamforming precision with reduced latency, accepting that some minor channel details are not fed back.
3Measurement precision
If channel sounding is performed frequently to maintain accuracy in dynamic environments, then beamforming accuracy is improved, but network overhead and interference increase
Solution Approach 1:
The patent implements periodic channel sounding at optimized intervals rather than continuous sounding. By using implicit feedback mechanisms that require less frequent updates, the system maintains channel state accuracy over longer periods, reducing the frequency of sounding transmissions and thereby reducing overall interference in the network.
Solution Approach 2:
The patent changes the feedback parameter format to be more compact and efficient. By using compressed representations, codebook indices, or differential feedback schemes, the system can maintain accurate channel tracking with fewer and smaller sounding transmissions, reducing the interference generated by frequent channel state information exchanges.
Data Source
AI summary
This disclosure describes systems, methods, and devices related to multi-user uplink channel sounding. A device may determine a channel sounding sequence with one or more access points (APs), wherein the channel sounding sequence comprises a null data packet announcement (NDPA) communicated with at least one of the one or more APs. The device may determine a first group of station devices (STAs) associated with a first basic service set (BSS). The device may cause to send a trigger frame to the first group of STAs to solicit an uplink NDP from each STA of the first group of STAs. The device may identify a first uplink NDP received from a first STA of the first group of STAs. The device may identify a second uplink NDP received from a second STA of a second group of STAs.