Antenna Calibration Factor Determination via UE Channel Estimation
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Solution Overview
Problem
Existing antenna calibration methods in MIMO systems face challenges due to mismatched uplink and downlink circuits, which lead to reduced signal-to-noise ratio and performance degradation, as they can only calibrate phase errors or introduce estimation errors when calibrating both amplitude and phase errors.
Innovation Solution
A method where the UE estimates and reports amplitude and phase information of downlink baseband channels to the base station, allowing for concurrent calibration of amplitude and phase errors, reducing sensitivity to channel estimation errors and Doppler spreading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional antenna calibration methods are used to calibrate phase errors, then phase calibration accuracy is improved, but amplitude calibration capability is lost
Solution Approach 1:
The patent segments the channel calibration process into distinct amplitude calibration and phase calibration stages. The UE first estimates and reports amplitude information (absolute channel estimation values) to the base station, which performs amplitude calibration. Subsequently, phase calibration is performed using traditional methods. This segmentation allows each calibration type to be performed with appropriate precision without interfering with the other, resolving the contradiction between phase calibration accuracy and amplitude calibration capability.
2Adaptability or versatility
If conventional antenna calibration methods are used to calibrate both amplitude and phase errors, then calibration coverage is improved, but estimation error increases
Solution Approach 1:
The patent applies preliminary action by having the UE report amplitude information (absolute channel estimation values) to the base station before performing phase calibration. The base station uses this pre-reported amplitude information to perform amplitude calibration first, establishing a corrected baseline. Then phase calibration is performed on this corrected baseline, which reduces the propagation of estimation errors through the entire calibration process, thereby maintaining higher precision while achieving comprehensive calibration coverage.
3Loss of information
If channel feedback is used in FDD systems, then channel information is obtained, but uplink resources are consumed
Solution Approach 1:
The patent extracts only the essential amplitude calibration information (absolute channel estimation values) from the full channel state information and reports only this extracted data to the base station. This selective extraction allows the base station to perform amplitude calibration without requiring the UE to feed back complete channel matrices, thereby obtaining necessary calibration information while significantly reducing uplink resource consumption compared to traditional FDD channel feedback approaches.
Data Source
AI summary
A method and device for reporting antenna calibration information and determining antenna calibration factor are provided by the present invention. When reporting the antenna calibration information, a user equipment (UE) estimates the downlink equivalent baseband channel from a plurality of antennas of the base station to the UE; according to the equivalent baseband channel, determines the amplitude response and delay value to be reported, and then reports the amplitude response and delay value to the base station. When determining the antenna calibration factor, according to the uplink signal sent by the UE on the base station-directed time-frequency resources, the base station determines the amplitude response and the delay value; according to the amplitude response and delay value reported by the UE and according to the amplitude response and delay value determined by the uplink signal, the base station calculates the antenna calibration factor. Because the UE pre-processing process is added, the sensitivity degrees to the channel estimation error and to the channel Doppler extension are reduced.