MIMO Sounding via Partial Antenna Subgroups
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Solution Overview
Problem
In MIMO communication systems, full channel calibration is challenging when the receiver can only estimate sub-channels for a limited number of transmit antennas, especially for access points with a large number of transmit antennas, due to limited computational capabilities or legacy technology, preventing effective beamforming for multiple client devices.
Innovation Solution
The access point performs multiple sounding sessions with client devices using different partial subgroups of transmit antennas, combining feedback information to determine a steering matrix for spatial stream modulation, allowing for full channel calibration even with receivers that support fewer transmit antennas, and iteratively updates the steering matrix based on strongest sub-channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full channel calibration is performed using all transmit antennas, then beamforming accuracy is improved, but receiver computational complexity increases beyond its capabilities
Solution Approach 1:
The patent divides the full set of transmit antennas into multiple partial subgroups, where each subgroup is used to transmit a portion of the sounding frame. The receiver only needs to estimate channels for the antennas in its assigned partial subgroup, significantly reducing computational complexity while maintaining overall system performance through coordinated transmission across all subgroups.
2Productivity
If the access point uses a large number of transmit antennas, then network capacity is improved, but channel calibration complexity increases
Solution Approach 1:
The access point segments its large antenna array into multiple partial subgroups, each handling a portion of the channel calibration process. This allows the system to support more client devices simultaneously while keeping the calibration complexity for each device manageable by only requiring estimation of a subset of transmit antenna channels.
Solution Approach 2:
Each receiver only performs channel estimation for a partial subgroup of transmit antennas rather than all antennas. This partial action approach allows the system to scale to more antennas and clients without proportionally increasing individual receiver complexity, as each device handles only the subset of antennas relevant to its service.
3Measurement precision
If the receiver estimates channels for all transmit antennas, then beamforming performance is improved, but processing time increases
Solution Approach 1:
The channel estimation process is segmented into multiple parallel tasks, where different receivers estimate channels for different partial subgroups of transmit antennas. This division of labor reduces the processing time for each individual receiver while the aggregate system maintains comprehensive channel knowledge across all antennas through coordinated estimation.
Data Source
AI summary
A wireless access point (AP) includes multiple transmit antennas and circuitry. The circuitry is configured to transmit multiple sounding frames to a receiver that includes one or more receive antennas, the sounding frames are transmitted via respective different partial subgroups of the transmit antennas, to receive from the receiver feedback information that specifies for each of the sounding frames a respective channel between the transmit antennas in the respective partial subgroup and the receive antennas, and, to determine a steering matrix based on the feedback information, and transmit to at least the receiver via at least some of the transmit antennas using the steering matrix.