MIMO Beamforming Channel Sounding via NDPA and NDP Frames
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Solution Overview
Problem
Current communication systems, such as WLAN, lack effective methods for rapidly and stably acquiring channel information of receivers for efficient data transmission and reception through beamforming using the MIMO scheme, which is essential for transmitting large-capacity data.
Innovation Solution
The proposed solution involves transmitting null data packet announcement (NDPA) and null data packet (NDP) frames to acquire channel information, with a checking unit to verify the receipt of these frames and retransmit or adjust accordingly, enabling the generation of a steering matrix for beamforming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If beamforming according to MIMO scheme is used to transmit large-capacity data, then data transmission rate is improved, but channel information acquisition reliability deteriorates due to lack of detailed methods
Solution Approach 1:
The system performs preliminary channel sounding by transmitting NDPA and NDP frames before actual data transmission. This preliminary action allows the receiver to measure and report channel information in advance, ensuring reliable channel knowledge is available when needed for high-rate data transmission through beamforming.
Solution Approach 2:
The receiver measures channel information from the NDP frame and feeds back this information to the transmitter through a beamforming report. This feedback mechanism ensures the transmitter has accurate channel knowledge to perform effective beamforming, resolving the reliability issue while maintaining high data rates.
2Productivity
If NDPA and NDP frames are transmitted to acquire channel information, then beamforming capability is improved, but transmission stability deteriorates when frames are not normally received
Solution Approach 1:
The system includes a checking unit that monitors whether the NDP frame was normally received, and a retransmission mechanism that sends NDPA and NDP frames again if reception failed. This beforehand cushioning prevents transmission instability by compensating for potential frame loss before it affects beamforming operation.
Solution Approach 2:
The checking unit provides feedback on frame reception status, enabling the transmitter to determine whether retransmission is needed. This feedback loop stabilizes the transmission process by ensuring channel information is successfully acquired before proceeding with beamforming data transmission.
3Productivity
If channel information is not properly acquired, then data transmission efficiency is reduced, but retransmission increases time consumption
Solution Approach 1:
The system performs channel sounding as a preliminary action before data transmission, separating the channel measurement phase from the data transmission phase. This allows efficient use of acquired channel information for beamforming while limiting retransmissions to only the sounding frames, minimizing time loss.
Solution Approach 2:
The checking unit monitors frame reception and triggers retransmission only when necessary. This selective feedback approach maintains data transmission efficiency by avoiding unnecessary retransmissions while ensuring channel information is properly acquired when beamforming is required.
Data Source
AI summary
Disclosed are an apparatus and a method for transmitting/receiving data by acquiring channel information of a terminal receiving data in a communication system providing services to users through beamforming according to a multi-input multi-output (MIMO) scheme, wherein so as to acquire channel information of the terminal for transmitting/receiving data through the beamforming according to the MIMO scheme, a null data packet announcement (NDPA) frame and a null data packet (NDP) frame are transmitted to the terminal, the beamforming frame is received from the terminal as a response of the null data packet announcement frame and the null data packet frame, and the channel information of the terminal included in the beamforming frame and the indication information on which the null data packet frame included in a control information field of the beamforming frame is normally received are checked.