Power Amplifier Compressed Reference Signals for Adaptive Distortion Control
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Solution Overview
Problem
Wireless communication systems face challenges in managing power amplifier non-linearity, leading to spectral regrowth, adjacent channel interference, and reduced power efficiency due to the use of power back-off and digital pre-distortion techniques, which do not fully address non-linear distortions caused by high peak-to-average power ratios.
Innovation Solution
Implementing power amplifier compressed reference signals to determine a UE's capability for digital post distortion processing, allowing a base station to select an optimal power amplifier compression level based on channel state feedback, using a set of uncompressed and compressed reference signals to manage power amplifier efficiency and reduce non-linear distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If power back-off and digital pre-distortion techniques are used to manage power amplifier non-linearity, then spectral regrowth and adjacent channel interference are reduced, but power efficiency decreases and non-linear distortions from high peak-to-average power ratios are not fully addressed
Solution Approach 1:
The base station transmits compressed reference signals with known compression levels before actual data transmission. The UE measures channel state information on these pre-compressed signals and reports back, enabling the base station to pre-determine the optimal compression level for subsequent transmissions, thereby avoiding the need for continuous power back-off while maintaining spectral cleanliness
Solution Approach 2:
The system implements a feedback mechanism where the UE reports channel state information based on measurements of compressed reference signals. This feedback loop enables the base station to adapt the power amplifier compression level dynamically, optimizing the balance between power efficiency and distortion management by continuously monitoring channel conditions
2Use of energy by moving object
If power amplifier compression level is increased to improve power efficiency, then power savings increase, but non-linear distortions and interference increase
Solution Approach 1:
The system dynamically adjusts the power amplifier compression level based on real-time channel state feedback. The base station selects from multiple predetermined compression levels (including zero compression) and switches between them according to channel conditions, enabling optimal power efficiency while maintaining acceptable distortion levels through adaptive rather than static compression
Solution Approach 2:
The invention changes the compression level parameter dynamically by transmitting reference signals at different compression levels and using UE feedback to determine the optimal level. This parameter variation allows the system to explore the trade-off between power efficiency and distortion, selecting the optimal operating point for each channel condition
3Reliability
If digital post distortion processing is implemented at the UE to correct non-linear distortions, then signal quality improves, but processing complexity and power consumption at the UE increase
Solution Approach 1:
Instead of requiring the UE to perform complex digital post-distortion processing, the base station performs compression level determination in advance using compressed reference signals. This preliminary action shifts the complexity to the base station side, where more computational resources are available, thereby reducing UE processing requirements while maintaining signal quality
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. The method includes transmitting a set of reference signals to a user equipment (UE), where the set of reference signals include a power amplifier uncompressed reference signal and a subset of compressed reference signals that are compressed with respective levels of power amplifier compression, receiving a channel state report from the UE that includes channel state feedback associated with the power amplifier uncompressed reference signal and each reference signal of the subset of compressed reference signals based at least in part on the UE performing a channel state measurement on each reference signal of the set of reference signals, selecting a power amplifier compression level for communications with the UE based at least in part on the channel state report, and communicating with the UE according to the selected power amplifier compression level.