Multi-AP Channel Sounding for Coordinated Beamforming and JT
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing technologies face challenges in efficient channel sounding for coordinated beamforming (CBF) and joint transmission (JT) in EHT networks, as well as resource allocation and signaling within an EHT target wake time (TWT) service period (SP), particularly in multi-AP operations.
Innovation Solution
Implementing a multi-AP channel sounding protocol that includes an indication field in NDPA frames to differentiate between JT and CBF, utilizing JT channel sounding to support CBF, and enhancing TWT signaling with multi-link TWT Information frames to manage resource allocation and STA presence across multiple access points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate channel sounding protocols are implemented for CBF and JT, then channel sounding accuracy is improved, but system complexity and overhead increase
Solution Approach 1:
The patent combines CBF and JT channel sounding procedures into a unified protocol. The same NDP transmission and CSI reporting mechanisms are used for both CBF and JT operations, eliminating the need for separate protocol implementations while maintaining accurate channel measurement capabilities for both coordinated beamforming and joint transmission scenarios.
Solution Approach 2:
The channel sounding protocol is designed to serve multiple functions - it can be used for both CBF channel measurement and JT channel measurement. The NDPA frame and NDP transmission structure are made universal to support both operational modes, reducing overall system complexity while preserving measurement precision through mode-indication fields.
2Device complexity
If joint transmission channel sounding is used to support coordinated beamforming, then implementation complexity is reduced, but channel measurement precision for CBF may be affected
Solution Approach 1:
The patent applies local quality by configuring STAs to perform specific measurement tasks based on the sounding type indication. When CBF is indicated, STAs measure channels from multiple APs for beamforming optimization; when JT is indicated, STAs measure channels for joint transmission optimization. This localized measurement approach ensures precision for each specific operation while using a unified protocol framework.
Solution Approach 2:
The system changes measurement parameters dynamically based on the operation type. The NDPA frame includes a sounding type indication that triggers different measurement and reporting behaviors. This parameter change mechanism allows the same physical protocol to achieve precise measurements tailored to either CBF or JT requirements without compromising accuracy.
3Measurement precision
If multiple NDP frames are transmitted for joint transmission, then channel information accuracy is improved, but transmission time and overhead increase
Solution Approach 1:
The patent uses preliminary action by transmitting all necessary NDP frames in advance during a dedicated sounding period before actual data transmission. The NDPA frame announces the upcoming NDP transmissions and enables STAs to prepare for simultaneous or sequential measurements. This preliminary sounding approach ensures accurate channel information is available before TWT service periods begin, avoiding delays during actual data transmission.
Solution Approach 2:
The channel sounding is performed periodically in dedicated sounding periods that are separate from data transmission periods. This periodic structure allows multiple NDP frames to be transmitted in a concentrated time window for accurate measurement, followed by a longer period for actual data transmission using the obtained channel information, thus balancing measurement accuracy with overall system efficiency.
4Measurement precision
If comprehensive STA presence signaling is implemented across multiple links, then resource allocation accuracy is improved, but signaling overhead increases
Solution Approach 1:
The patent segments STA presence signaling by link, allowing each link to independently signal STA presence status. Instead of a single comprehensive signaling mechanism, each wireless link maintains its own presence indication, enabling precise resource allocation per link while reducing overall signaling overhead through localized, link-specific signaling rather than global signaling for all links.
Data Source
Figure 1~2
Figure 3~5B
Figure 5C~6
AI summary
An access point station (AP) configured for multi-AP operation in an EHT network, when configured for multi-AP coordinated beamforming (CBF) and/or multi-AP joint transmission (JT) may operate as a master AP (API) and implement a multi-AP channel sounding protocol. The AP1 may be configured to encode a NDPA frame for transmission to poll one or more intra-BSS stations (STA11...1N) associated with the AP1 and one or more OBSS STAs (inter-BSS STAs) (STA21...2N) associated with a slave second AP (AP2). The AP1 may also be configured to encode a first NDP (NDP1) frame for transmission an SIFS after the NDPA frame. The NDP1 may be transmitted concurrently with a second NDP (NDP2) transmitted by the AP2. The AP1 may also be configured to encode a beam-forming refinement phase (BFRP) trigger frame for transmission an SIFS after the NDP1 frame. The BFRP trigger frame may identify both the one or more BSS stations and the one or more OBSS STAs. The AP1 may also be configured to decode CSI report frames in TB PPDUs received from the BSS stations in the BFRP trigger frame and CSI report frames received from the OBSS STAs identified in the BFRP trigger frame.