Channel Emulator Self-Calibration for MIMO RF Signal Chains
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Solution Overview
Problem
Calibration of phase, amplitude, delay, and flatness parameters in channel emulators is time- and cost-intensive due to the exponential increase in signal chains in MIMO RF environments, making it difficult to maintain accuracy in RF test platforms.
Innovation Solution
An end-to-end self-calibration technique using a secondary calibration signal chain with a sequence generator to create a signal with known patterns, allowing for real-time measurement and correction of phase, amplitude, and flatness parameters within the channel emulator, replacing expensive external signal analyzers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external signal analyzers are used to calibrate channel emulator signal chains, then measurement precision is improved, but device complexity and cost increase exponentially with MIMO size
Solution Approach 1:
The channel emulator performs self-calibration by injecting calibration signals through its own signal chains and measuring the outputs using its internal resources. The baseband processor analyzes the received calibration signals and automatically adjusts delay, phase, amplitude, and flatness parameters without requiring external calibration equipment, making the system self-sufficient for calibration tasks
Solution Approach 2:
The baseband processor serves multiple functions: it processes normal communication signals, generates calibration signals, measures channel characteristics, and performs parameter adjustments. This multi-functionality eliminates the need for separate dedicated calibration equipment, reducing system complexity while maintaining calibration precision
2Measurement precision
If traditional external calibration equipment is used, then measurement precision is maintained, but productivity decreases due to time-intensive calibration processes
Solution Approach 1:
The calibration process is designed to be continuous and integrated with normal operations. Calibration signals can be injected and measured without interrupting the channel emulator's primary function, and parameters can be adjusted in real-time, eliminating the need for separate calibration sessions and improving overall productivity
Solution Approach 2:
Calibration parameters are pre-calculated based on received signal characteristics, allowing the system to proactively adjust delay, phase, amplitude, and flatness parameters before they cause measurement errors. This preventive approach maintains precision while reducing the time needed for reactive recalibration
3Reliability
If calibration is performed frequently to maintain accuracy, then reliability is improved, but loss of time and increased cost occur
Solution Approach 1:
The system continuously monitors channel characteristics by analyzing received calibration signals and uses this feedback to automatically adjust parameters when drift is detected. This closed-loop approach maintains reliability by correcting parameters only when necessary, rather than following a fixed recalibration schedule, thus reducing time loss while ensuring parameter stability
Solution Approach 2:
The channel emulator autonomously detects parameter drift through its own measurement capabilities and performs self-correction without external intervention. This self-service mechanism ensures continuous reliability while eliminating the time and cost associated with manual recalibration schedules
Data Source
AI summary
The technology disclosed teaches a system and methods for end-to-end self-calibration of a channel emulator, wherein the channel emulator includes at least one channel emulator signal chain and at least one integrated parallel calibration signal chain. The channel emulator signal chain further includes an input signal, a first signal conditioner, a first analog-to-digital converter, a baseband processor, second signal conditioner, and an output. The integrated parallel calibration signal chain further includes a sequence generator, wherein the sequence generator is configured to generate a pseudo-random sequence upon which a calibration analysis signal is overlayed. On the supplying side, the sequence generator is coupled to a second digital-to-analog converter for supplying the calibration analysis signal to be processed by the channel emulator signal chain. On the evaluating side, the sequence generator is coupled to a comparator for evaluating results of the processed calibration analysis signal.