Wireless LAN Channel Feedback Consolidation
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Solution Overview
Problem
Current wireless LAN systems face challenges in efficiently measuring and reporting channel information for joint transmission across multiple access points, leading to increased latency and overhead in channel information measurement and feedback processes.
Innovation Solution
A method and device for a station (STA) to receive a null data packet announcement (NDP-A) frame from a first access point (AP), measure channels for both the transmitting AP and non-transmitting APs, and transmit acquired channel information to the first AP, utilizing NDP frames received from multiple APs to facilitate joint transmission, thereby reducing latency and overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If channel information is measured and reported for each AP separately, then measurement accuracy is maintained, but latency and overhead increase
Solution Approach 1:
The patent combines channel information measurement and feedback for multiple APs into a single unified process. The STA measures channels from multiple APs simultaneously and reports all channel information in one feedback message, rather than measuring and reporting separately for each AP. This merging approach reduces the total number of feedback messages and processing steps, thereby reducing latency while maintaining measurement accuracy through the use of NDP frames for precise channel estimation.
Solution Approach 2:
The patent employs preliminary action by having the APs transmit NDP (Null Data Packet) frames before actual data transmission. These NDP frames are used to pre-measure and pre-report channel information, allowing the system to have channel state information available before data transmission begins. This preliminary measurement and feedback process reduces the latency during actual data transmission while maintaining accurate channel information.
2Measurement precision
If channel information is measured and reported for each AP separately, then individual AP channel accuracy is maintained, but feedback overhead increases
Solution Approach 1:
The patent merges the feedback messages for multiple APs into a single consolidated feedback transmission. Instead of sending separate feedback messages for each AP's channel information, the STA combines all channel measurements into one feedback message that includes information for multiple APs. This reduces the total number of feedback transmissions and associated overhead while preserving individual AP channel accuracy through proper encoding of each AP's specific channel information within the unified feedback structure.
3Measurement precision
If multiple APs transmit NDP frames separately, then individual channel measurement accuracy is maintained, but measurement time increases
Solution Approach 1:
The patent implements periodic action by having multiple APs transmit NDP frames in a coordinated, periodic manner. Instead of transmitting simultaneously or in random sequences, the APs transmit NDP frames at regular intervals in a structured sequence. This periodic transmission pattern allows the STA to efficiently process and distinguish signals from different APs while reducing the total measurement duration compared to separate, non-coordinated measurements, while maintaining individual channel measurement accuracy through proper signal separation and processing.
Data Source
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AI summary
A method for reporting channel information by a station (STA) in a wireless LAN (WLAN) system according to an embodiment of the present invention comprises the steps of: receiving a null data packet announcement (NDP-A) frame from a first access point (AP); when it is determined that the NDP-A frame is for joint transmission of a plurality of APs, measuring a channel for a first AP having transmitted the NDP-A frame and a channel for at least one second AP channel which has not transmitted the NDP-A frame; and transmitting channel information for the plurality of APs, which has been acquired according to a result of the channel measurement, to the first AP, wherein when the NDP-A frame is for the joint transmission, the STA can acquire channel information relating to the plurality of APs through a plurality of NDP frames received from the plurality of APs after receiving the NDP-A frame one time.