Probability-Maintained Notch Signals for Nonlinear Compensation Evaluation
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Solution Overview
Problem
Existing methods for evaluating nonlinear compensation performance in communication systems, such as BER, EVM, ACPR, and out-of-band IMD, are inconvenient, expensive, or lack accuracy in establishing a direct correlation with the actual performance of transceiver devices, especially for digital pre-distortion evaluation.
Innovation Solution
Utilizing a probability-maintained notch signal with an unchanged probability density function after notching, the method involves generating, processing, and measuring the signal's spectrum to estimate nonlinear compensation performance, establishing a direct correspondence with the bit error rate (BER) through noise power ratio (NPR).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If BER or EVM analysis method is used to evaluate nonlinear compensation performance, then measurement accuracy is improved, but device complexity and cost increase due to requiring digital storage oscilloscope and receiver
Solution Approach 1:
The patent extracts the essential measurement function from the complex BER/EVM analysis system and concentrates it into a single spectrum analyzer. By using a probability-maintained notch signal, the method isolates the nonlinear distortion components and enables direct measurement of in-band regression power, eliminating the need for digital storage oscilloscope and receiver while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces a probability-maintained notch signal as an intermediary test signal that bridges the gap between the nonlinear compensation system and the spectrum analyzer. This special test signal maintains its probability density function through the nonlinear compensation process, allowing the spectrum analyzer to directly measure the residual in-band regression power without requiring complex signal processing equipment.
2Ease of operation
If ACPR or out-of-band IMD measurement method is used, then ease of operation is improved, but measurement precision deteriorates due to lack of direct correlation with BER
Solution Approach 1:
The patent applies local quality by focusing the measurement on the specific frequency region where nonlinear distortion occurs. By using a probability-maintained notch signal with a notch at a specific frequency, the method locally isolates the in-band regression power at the notch frequency, enabling direct correlation with BER while maintaining the operational simplicity of spectrum analysis.
Solution Approach 2:
The patent changes the signal parameter by using a probability-maintained notch signal instead of conventional test signals. This signal has a unique property where its probability density function remains unchanged after passing through the nonlinear compensation system, allowing direct measurement of in-band regression power through spectrum analysis and establishing a direct correlation with BER.
3Ease of operation
If conventional test signals are used for ACPR measurement, then ease of operation is improved, but measurement precision deteriorates due to bandwidth limitations affecting wideband signals
Solution Approach 1:
The patent applies dynamics by designing a probability-maintained notch signal that adapts to the bandwidth characteristics of the system. The signal's probability density function remains invariant through the nonlinear compensation process, allowing accurate measurement of in-band regression power across different bandwidths without being limited by the bandwidth constraints of conventional test signals or measurement equipment.
Data Source
AI summary
A method, an apparatus and a communication system of evaluating a nonlinear compensation performance. The method for evaluating a nonlinear compensation performance comprises: evaluating a nonlinear compensation performance by using a probability-maintained notch signal as a test signal; the probability-maintained notch signal having a probability density function (PDF) that is maintained unchanged after notching as compared with before notching.