Non-Constant Envelope Reference Signals for PA Nonlinearity Estimation
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Solution Overview
Problem
Wireless communication systems face inefficiencies due to nonlinear components like high-power amplifiers distorting signals with high peak-to-average power ratio (PAPR), leading to reduced power efficiency, which existing methods like power backoff cannot fully address without compromising transmission quality.
Innovation Solution
A transmitter generates a reference signal with a non-constant envelope for nonlinearity estimation, allowing for digital pre-distortion (DPD) and post-distortion (DPoD) operations to adjust amplifier coefficients, thereby improving signal fidelity and power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power backoff is applied to reduce signal distortion from nonlinear components, then signal fidelity is improved, but power efficiency deteriorates
Solution Approach 1:
The patent changes the parameter of reference signal envelope from constant to non-constant, enabling the signal to traverse the full dynamic range of nonlinear components. This allows accurate estimation of nonlinearity characteristics across different power levels, enabling DPD to achieve high signal fidelity without requiring aggressive power backoff, thus maintaining power efficiency.
2Stability of the object's composition
If constant envelope reference signals are used to avoid nonlinearity effects, then amplifier operation stability is improved, but nonlinearity estimation capability deteriorates
Solution Approach 1:
Instead of using constant envelope signals to avoid nonlinearity effects, the patent inverts the approach by deliberately using non-constant envelope reference signals that actively traverse the nonlinear region. This allows the system to measure and characterize nonlinearity effects directly, enabling accurate DPD compensation while maintaining amplifier operation in the saturated region for maximum efficiency.
3Use of energy by moving object
If amplifiers operate in saturated region for maximum efficiency, then power efficiency is improved, but signal distortion increases
Solution Approach 1:
The patent applies preliminary action by using non-constant envelope reference signals to pre-characterize the nonlinear distortion effects before actual data transmission. The estimated nonlinearity characteristics are stored and used to pre-compensate (DPD) or post-compensate (DPoD) signals, allowing amplifiers to operate continuously in the saturated high-efficiency region while maintaining low distortion through digital compensation.
Data Source
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AI summary
A transmitter may be configured to generate a reference signal having a non-constant envelope for nonlinearity estimation by a receiver. The transmitter may transmit the reference signal. A receiver may be configured to receive, from the transmitter, the reference signal having the non-constant envelope. The receiver may estimate at least one nonlinearity characteristic based on the reference signal having the non-constant envelope. The receiver may transmit feedback based on the at least one nonlinearity characteristic and/or perform at least one digital post distortion (DPoD) operation based on the at least one nonlinearity characteristic.