DPD Signal Pre-Equalization for Power Amplifier Spectral Spread
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Solution Overview
Problem
Existing wireless communication systems face challenges in maintaining signal quality due to the non-linear behavior of power amplifiers, which causes spectral spread and degradation in in-band signal quality, particularly when using digital pre-distortion (DPD) as existing filters remove high spectral components of the DPD signal, leading to unintended spectral spread into undesirable frequencies.
Innovation Solution
Implementing pre-equalization on the signal to counteract the non-linear effects of power amplifiers by amplifying the high-spectral components of the DPD signal based on the frequency response of the transmit filter, ensuring the DPD signal survives filtering and effectively offsets the non-linear behavior of the power amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If digital pre-distortion is applied to counteract power amplifier non-linearity, then spectral spread is reduced, but transmit filter removes high spectral components causing unintended spectral spread into undesirable frequencies
Solution Approach 1:
The patent applies pre-equalization before the transmit filter to pre-amplify the high spectral components of the DPD signal. This preliminary action ensures that when the transmit filter removes these components, the DPD effect is preserved and the signal maintains proper spectral characteristics without unintended spread into prohibited frequencies.
Solution Approach 2:
The pre-equalization performs a preliminary anti-action by amplifying the high spectral components that would otherwise be removed by the transmit filter. This counteracts the filter's effect in advance, ensuring the DPD signal survives filtering and continues to effectively offset power amplifier non-linearity without causing spectral spread into undesirable frequencies.
2Length of moving object
If power amplifier transmission power is increased to improve transmission range, then transmission range is extended, but non-linear behavior degrades in-band signal quality
Solution Approach 1:
Digital pre-distortion is applied in advance to the signal before it enters the power amplifier. This preliminary distortion is designed to counteract the expected non-linear behavior of the amplifier at high power levels, allowing the system to transmit at higher powers for extended range while maintaining in-band signal quality through compensatory distortion.
Data Source
AI summary
Methods and systems may include performing pre-equalization of a signal for transmission, where the pre-equalization includes amplifying a non-linear portion of the signal based on a frequency response of a transmit filter for the non-linear portion of the signal. In such a method or system, the non-linear portion may be configured to counteract spectral spread caused by a power amplifier, and the amplifying of the pre-equalization may cause the non-linear portion of the signal to survive filtering by the transmit filter such that the non-linear portion of the signal arrives at the power amplifier to counteract the spectral spread of the signal for transmission caused by the power amplifier.