Dynamic Power Back-Off for AGC and DPD Signal Adjustment
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Solution Overview
Problem
The existing power adjustment methods in cloud radio access networks, particularly when combined with digital pre-distortion algorithms, fail to effectively improve the third-order intermodulation distortion (IMD3) spectrum performance and error vector magnitude (EVM) performance of in-phase and quadrature (I/Q) signals due to fixed power back-off, which does not adapt to real-time changes in CPRI I/Q traffic.
Innovation Solution
A power adjustment method that involves automatic gain control (AGC) processing, digital pre-distortion (DPD) processing, and dynamic output power adjustment based on calculated output power back-off (OBO) values, allowing real-time adaptation to traffic changes to reduce non-linearity in the power amplifier, thereby enhancing IMD3 and EVM performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed back-off is performed on the output power of the power amplifier, then the non-linearity of the power amplifier is reduced and IMD3 spectrum performance and EVM performance are improved, but the output power cannot be adjusted in real-time to adapt to changing CPRI I/Q traffic
Solution Approach 1:
The patent implements dynamic output power adjustment by calculating an OBO value based on real-time gain values obtained through AGC processing. The system transitions from fixed back-off to dynamic back-off, where the output power is continuously adjusted according to changing traffic conditions. This is achieved through the formula: adjusted output power = calculated output power - OBO value, where OBO = 10lg(1/G²), making the system adaptable to real-time traffic variations while maintaining performance improvements.
Solution Approach 2:
The patent employs AGC (Automatic Gain Control) processing to obtain real-time gain values of the to-be-output signal, which then feeds into the OBO calculation. This feedback mechanism allows the system to continuously monitor signal characteristics and adjust the output power accordingly. The gain value obtained through AGC serves as feedback to dynamically determine the appropriate back-off level, ensuring both performance improvement and adaptability to traffic changes.
2Productivity
If output power is increased to improve transmission efficiency, then higher modulation methods can be supported, but non-linearity of the power amplifier increases and IMD3 spectrum performance deteriorates
Solution Approach 1:
The patent changes the parameter of output power through dynamic adjustment using the OBO value. By calculating the appropriate back-off level based on real-time gain values and adjusting the output power accordingly, the system optimizes the balance between transmission efficiency and signal quality. This parameter change allows the system to operate at optimal power levels that support higher modulation methods while maintaining acceptable IMD3 performance.
Data Source
AI summary
This application provides a power adjustment method and apparatus. The method includes obtaining a to-be-output signal, performing first automatic gain control (AGC) processing on the to-be-output signal to obtain the to-be-output signal on which the first AGC processing is performed, and to obtain a gain value of the to-be-output signal. The method also includes performing digital pre-distortion (DPD) processing on the to-be-output signal on which the first AGC processing is performed, to obtain the to-be-output signal on which the DPD processing is performed. The method further includes calculating an output power back-off (OBO) value based on the gain value, adjusting, based on the OBO value, output power of the to-be-output signal on which the DPD processing is performed, and sending, to a signal receive end, the to-be-output signal on which the power adjustment is performed.