Beamformed Uplink PPDU Triggering with NDPR Feedback
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Solution Overview
Problem
Existing wireless communication systems, particularly the 802.11ax standard, do not support beamforming for trigger-based uplink physical layer protocol data units (PPDUs), leading to limited performance in simultaneous uplink transmissions from multiple stations.
Innovation Solution
A system and method involving an access point (AP) that sends a null data packet request (NDPR) frame to stations (STAs), enabling them to send back NDP PPDUs, allowing the AP to compute precoders and facilitate beamforming for efficient uplink transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If beamforming is not supported for trigger-based uplink PPDUs, then device complexity is reduced, but throughput and transmission performance deteriorate
Solution Approach 1:
The system performs preliminary channel estimation by transmitting null data packets (NDPs) before actual data transmission. The AP sends NDPs to STAs, which respond with feedback, enabling the computation of precoding matrices in advance. This preliminary action allows beamforming to be established before trigger-based uplink transmissions, improving throughput without adding complexity to the data transmission phase.
Solution Approach 2:
The patent introduces an intermediary feedback mechanism where STAs transmit channel state information back to the AP after receiving NDPs. This intermediary step provides the necessary channel information for beamforming computation, enabling efficient uplink transmissions without requiring complex real-time beamforming capabilities at the STA side.
2Productivity
If simultaneous uplink transmissions from multiple stations are not beamformed, then device complexity is reduced, but transmission efficiency and signal quality deteriorate
Solution Approach 1:
The system segments the uplink transmission process into distinct phases: channel estimation phase where AP transmits NDPs to individual STAs, feedback phase where STAs respond with channel information, and data transmission phase where beamformed uplink PPDUs are sent. This segmentation allows beamforming to be applied selectively to simultaneous transmissions, improving efficiency while managing complexity through structured phase separation.
3Productivity
If beamforming computation is not performed at the AP, then AP device complexity is reduced, but uplink transmission performance deteriorates
Solution Approach 1:
The system implements self-service beamforming where the AP autonomously computes precoding matrices using channel information received from STA feedback. The AP independently performs the beamforming computation and applies it to subsequent uplink transmissions without requiring external assistance or complex coordination, improving performance while keeping the implementation self-contained at the AP side.
Data Source
AI summary
A system and method for triggering beamformed uplink (UL) physical layer protocol data units (PPDUs) are disclosed. The system comprises an access point (AP) and one or more stations (STAs). The AP sends a soliciting frame to the one or more STAs, wherein the frame comprises a null data packet, NDP, request, NDPR, indicator and receive an NDP PPDU from each of the one or more solicited STAs. The AP, then computes the precoder for each of the one or more solicited STAs and send the one or more solicited STA a trigger frame with a beamforming report. The AP receives from each of the STAs one or more beamformed UL data packets and sends a block acknowledgement to the one or more solicited STAs indicating the successful receipt of the one or more beamformed UL data packets.