Baseband Correction Device for UMTS Crest Factor Reduction
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Solution Overview
Problem
In UMTS mobile radio standards, high crest factors in signals lead to excessive power requirements and costs for base station amplifiers due to the need for large power amplifiers to maintain signal quality and low error rates, with existing methods for reducing crest factor causing spectral broadening and errors in adjacent channels.
Innovation Solution
A correction device is placed between signal sources and shaping filters to directly reduce the signal dynamic range in baseband, using components that estimate frequency responses and adjust amplitudes and phases to lower the crest factor without causing spectral broadening, allowing for reduced amplifier power consumption and improved signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large power amplifiers are used to maintain signal quality with high crest factors, then signal quality and low error rates are improved, but power consumption and costs increase
Solution Approach 1:
The invention applies preliminary action by reducing the crest factor of the modulated signal before it reaches the power amplifier. The correction device processes the signal in advance to lower its dynamic range, allowing the amplifier to operate more efficiently without sacrificing signal quality. This prevents the need for oversized amplifiers designed to handle peak crest factor values.
2Use of energy by moving object
If crest factor reduction methods are applied, then power consumption is reduced, but spectral broadening and errors in adjacent channels occur
Solution Approach 1:
The invention employs feedback by using the frequency response information of the shaping filter to guide the correction device's operation. The system continuously adapts its crest factor reduction based on the actual filter characteristics, ensuring that signal components are adjusted in a way that prevents spectral broadening and interference with adjacent channels while maintaining power efficiency.
3Power
If crest factor is reduced in parallel signal paths, then amplifier size is reduced, but device complexity increases
Solution Approach 1:
The invention applies segmentation by dividing the correction function into separate processing stages for different signal paths. Each parallel signal path receives independent correction processing, allowing the system to manage complexity in a modular way while achieving overall crest factor reduction across all transmitted signals.
Data Source
AI summary
To reduce the crest factor of a total signal, the signal dynamic range is corrected in baseband upstream of the interpolation filters. To this end, provision is made for the input of a correction device to be coupled to at least two signal sources which are designed to provide digital signals on different frequency bands. The correction device is designed to determine correction factors from the digital signals applied to the input and use them to alter the respective digital signals. The output of the correction device is coupled to a first and at least one second interpolation filter. This allows reduction of the signal dynamic range in baseband, which reduces the crest factor without having to accept substantial losses in signal quality.