Antenna Array Calibration Using Outbound Traffic Signals
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Solution Overview
Problem
Existing antenna array calibration methods disrupt normal outbound traffic signals, leading to reduced network capacity, data throughput, and potential non-compliance with standards, especially in multi-standard base stations.
Innovation Solution
The method calibrates antenna arrays using outbound traffic signals as feedback and reference, estimating impairments and applying equalizer taps to remove distortion without interrupting normal operations, ensuring compliance across various standards and conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If special calibration signals are injected into the transmit path for antenna array calibration, then phase distortion in transmit paths can be removed, but normal outbound traffic signals are interrupted and degraded, reducing network capacity and data throughput
Solution Approach 1:
The patent makes the outbound traffic signals serve dual purposes: both as normal communication signals and as calibration reference signals. By using the same traffic signals for both data transmission and phase distortion measurement, the system eliminates the need for separate calibration signals, thereby avoiding interruption of normal traffic while still achieving calibration functionality
Solution Approach 2:
The system uses its own outbound traffic signals to perform self-calibration. The base station captures its transmitted traffic signals through feedback paths and uses them as reference signals for impairment estimation, enabling the system to calibrate itself without external intervention or special calibration signals that would disrupt normal operation
2Manufacturing precision
If special calibration signals are used for antenna array calibration, then phase distortion can be compensated, but standards compliance is violated and regulatory requirements are not met in multi-standard base stations
Solution Approach 1:
The patent employs outbound traffic signals that already comply with various communication standards for calibration purposes. Since these signals are part of the normal standardized communication protocol, using them for calibration maintains standards compliance while achieving phase distortion compensation, unlike proprietary calibration signals that would violate standards
3Reliability
If transmission power is increased to compensate for phase distortions, then signal reception and decoding improve, but system load increases and power available for other terminals decreases
Solution Approach 1:
The patent applies preliminary calibration to remove phase distortions before transmission occurs. By pre-compensating for impairments in the transmit paths using equalizer taps derived from traffic signal analysis, the system ensures proper signal phase relationships without needing to increase transmission power, thereby maintaining energy efficiency while improving reception quality
4Measurement precision
If transmission power is increased to compensate for phase distortions, then signal decoding accuracy improves, but interference with other terminals increases and signal quality for other terminals deteriorates
Solution Approach 1:
The system performs preliminary calibration to correct phase distortions in the transmit paths before signal transmission. By ensuring proper phase alignment through equalization, the transmitted signals maintain their intended beam patterns and directional characteristics, preventing unintended interference with other terminals while still achieving accurate decoding
Data Source
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AI summary
An antenna array of a base station is calibrated using outbound traffic signals. The outbound traffic signals are captured for use as reference signals before the outbound traffic signals enter transmit paths in a radio unit of the base station. The outbound traffic signals are captured for use as a feedback after the outbound traffic signals exit the transmit paths. Each of the reference signals is one of the outbound traffic signals to be transmitted. An impairment estimator estimates the impairment for each of the outbound traffic signals based on the feedback signal and the reference signals. For each transmit path, a set of weights of an all-pass filter is determined, where the all-pass filter has a frequency response that approximates the impairment estimation in an occupied frequency region where reference signal power is above a threshold. The set of weights is inversed to obtain equalizer taps for each of the transmit paths.