Radio Unit Downlink Gain Compensation Without DPD Re-Convergence
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Solution Overview
Problem
Existing downlink gain compensation solutions in radio units are inefficient due to long gain estimation and compensation periods, errors in phase compensation/gain regulation, and instability caused by re-convergence of digital pre-distortion calculations.
Innovation Solution
A device and method for downlink gain compensation in a radio unit, comprising a pre-distortion circuit, a digital gain adjuster, a gain determiner, and a first gain controller, which work together to accurately determine and adjust the downlink gain, reducing errors and instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If software-based gain compensation is used, then gain adjustment capability is provided, but compensation period becomes long and system stability deteriorates
Solution Approach 1:
The patent replaces software-based gain compensation with a hardware-based solution using a voltage variable amplifier (VVA) and observation receiver. This hardware implementation enables real-time gain compensation without the processing delays inherent in software-based approaches, thereby reducing the compensation period while maintaining gain adjustment capability.
Solution Approach 2:
The observation receiver continuously monitors the output RF signal and feeds back observation signals to automatically determine current gain. This self-monitoring and self-adjusting mechanism eliminates the need for external control systems, reducing compensation time and improving system responsiveness.
2Measurement precision
If digital pre-distortion is applied, then gain compensation is achieved, but phase compensation errors and calculation instability occur
Solution Approach 1:
The patent replaces complex digital pre-distortion calculations with a simpler hardware-based voltage variable amplifier system. This substitution eliminates the computational complexity that causes phase compensation errors and calculation instability, while maintaining accurate gain compensation through direct hardware control.
Solution Approach 2:
The observation receiver acts as an intermediary that continuously monitors output signals and provides feedback to the VVA controller. This intermediary mechanism enables real-time adaptation without requiring complex pre-distortion calculations, improving both accuracy and stability.
3Reliability
If temperature and frequency compensation is implemented, then downlink gain variation is corrected, but device complexity increases
Solution Approach 1:
The voltage variable amplifier serves multiple functions: it performs gain compensation, temperature compensation, and frequency compensation simultaneously. This multi-functionality reduces overall system complexity compared to having separate compensation mechanisms for each parameter.
Solution Approach 2:
The system automatically monitors temperature and frequency parameters and adjusts the VVA gain accordingly without requiring external intervention. This self-adjusting capability simplifies the control architecture while maintaining comprehensive compensation for various operating conditions.
Data Source
AI summary
Device and method are disclosed for downlink gain compensation at a radio unit. According to an embodiment, the device comprises a pre-distortion circuit, a digital gain adjuster, a gain determiner and a first gain controller. The pre-distortion circuit is configured to generate and apply a pre-distortion to an input signal. The digital gain adjuster is configured to apply an adjustable gain to an output signal from the pre-distortion circuit. The gain determiner is configured to determine a gain difference between a target downlink gain and current downlink gain. The first gain controller is configured to control the digital gain adjuster based on the gain difference. A radio unit comprising the device is also disclosed.