MU-MIMO Beamforming Calibration Using Uplink Channel Estimation
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Solution Overview
Problem
Existing wireless communication systems face challenges in achieving high-quality communication due to estimation errors and calibration issues in implicit feedback beamforming, particularly in MU-MIMO systems, leading to degraded throughput and communication quality.
Innovation Solution
A wireless communication apparatus and method that includes generating format designation information, estimating uplink propagation channel information, calculating calibration coefficients, and using transmission weight values to improve communication quality by applying implicit feedback beamforming in MIMO transmission systems, even when propagation channel information is not obtained from multiple data reception stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If implicit feedback beamforming is used in MU-MIMO systems, then spatial multiplexing transmission efficiency is improved, but estimation errors and calibration issues degrade communication quality
Solution Approach 1:
The patent implements explicit feedback mechanisms where terminal stations transmit channel state information (CSI) to the base station. This allows the base station to calculate accurate transmission weight values for beamforming, resolving the estimation errors inherent in implicit feedback methods while maintaining spatial multiplexing efficiency.
Solution Approach 2:
The patent performs preliminary calibration of transmission and reception circuits before actual data transmission. By pre-calibrating the system and obtaining downlink channel information through explicit feedback, the base station can prepare accurate transmission weight values in advance, eliminating calibration issues during communication.
2Reliability
If downlink channel information is obtained through terminal station estimation method, then communication quality is improved, but additional communication time is required
Solution Approach 1:
The patent combines uplink and downlink channel estimation processes by utilizing the reciprocity of wireless channels. The base station estimates downlink channel information based on uplink channel measurements, merging the estimation functions and eliminating the need for separate downlink channel feedback transmission.
Solution Approach 2:
The base station performs self-service by autonomously estimating downlink channel information from uplink measurements without requiring terminal stations to explicitly feedback channel state information. This self-estimation capability reduces communication overhead and time while maintaining accurate channel knowledge.
3Manufacturing precision
If calibration coefficients are calculated using correlation of first calibration coefficients in frequency direction, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent transforms calibration coefficients from the frequency domain to the time domain using inverse fast Fourier transform (IFFT). By changing the domain parameter from frequency to time, the system achieves accurate calibration while simplifying the processing operations through efficient time-domain convolution instead of complex frequency-domain correlations.
Data Source
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AI summary
A wireless communication apparatus includes a designation unit which generates format designation information for designating a format of transmission and reception for another wireless communication apparatus, a first transmission unit which wirelessly transmits the format designation information to the other wireless communication apparatus, an acquisition unit which acquires a packet, a propagation channel estimation unit which estimates uplink propagation channel information indicating a propagation channel from the other wireless communication apparatus to the wireless communication apparatus based on the packet, a calibration coefficient calculation unit which calculates a calibration coefficient based on downlink propagation channel information indicating a propagation channel from the wireless communication apparatus to the other wireless communication apparatus and the uplink propagation channel information, a transmission weight value calculation unit which calculates a transmission weight value based on the calibration coefficient and the uplink propagation channel information, and a second transmission unit which wirelessly transmits a predetermined signal to the other wireless communication apparatus based on the transmission weight value.