Adaptive Nonlinear Receiver Modeling for Phase-Noise-Tolerant Modulation
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Solution Overview
Problem
Existing communication systems are power hungry and spectrally inefficient, particularly due to the degradation of complex linear modulation schemes in the presence of phase noise and non-linear distortion, which increases the gap between desired and actual spectral efficiency.
Innovation Solution
An adaptive non-linear model is implemented in communication systems, where a receiver generates estimates of transmitted symbols using a sequence estimation process that incorporates a non-linear model, adapting based on communication information to improve tolerance to non-linearity and spectral efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher-order modulation schemes are used to increase throughput, then spectral efficiency is improved, but sensitivity to non-linear distortion and phase noise increases
Solution Approach 1:
The patent transforms the received signal through mathematical operations including frequency shifting, filtering, and scaling to convert a higher-order modulation signal into an equivalent lower-order modulation signal. This parameter transformation allows the system to achieve higher spectral efficiency while maintaining robustness against non-linear distortion by processing the signal in a domain where it behaves like a more resilient modulation scheme
Solution Approach 2:
The patent introduces an intermediary transformation process that acts as a bridge between the higher-order modulation scheme and the receiver. This intermediary includes frequency domain filtering and signal conditioning that separates the high-order modulation components from noise and distortion, allowing accurate recovery without direct exposure to non-linear effects
2Productivity
If complex linear modulation schemes are used, then spectral efficiency is improved, but performance degrades in the presence of phase noise and non-linear distortion
Solution Approach 1:
The patent replaces traditional time-domain equalization methods with a frequency-domain transformation approach. By converting the signal to the frequency domain, applying selective filtering, and transforming back, the system achieves phase noise and non-linear distortion compensation without relying on complex adaptive equalizers that struggle under these conditions
Solution Approach 2:
The patent applies preliminary signal transformation and filtering operations before the main detection process. By pre-processing the signal to remove distortion components and condition the phase characteristics early in the reception chain, the system prevents degradation before it affects the demodulation process
Data Source
AI summary
A receiver may be operable to generate estimates of transmitted symbols using a sequence estimation process that may incorporate a non-linear model. The non-linear model may be adapted by the receiver based on particular communication information that may be indicative of non-linearity experienced by the transmitted symbols. The receiver may generate a reconstructed signal from the estimates of the transmitted symbols. The receiver may adapt the non-linear model based on values of an error signal generated from the reconstructed signal, and the values of the error signal may be generated from a portion of the generated estimates that may correspond to known symbols and/or information symbols. The values of the error signal corresponding to the known symbols may be given more weight in an adaptation algorithm, and the values of the error signal corresponding to the information symbols may be given less weight in the adaptation algorithm.