Shared Feedback DPD for Massive MIMO Amplifier Distortion
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Solution Overview
Problem
Massive MIMO systems face inefficiencies and increased costs due to the need for extensive hardware and power consumption in implementing digital predistortion (DPD) architectures to correct nonlinear distortions in RF power amplifiers, especially when feedback paths are provided for each amplified signal path.
Innovation Solution
The proposed solution involves a circuitry design with selective feedback paths and dynamic routing logic, allowing feedback to be shared among multiple input signals, with the option to power down non-selected paths, and grouping processing logic to reduce hardware and power requirements while maintaining high performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If digital predistortion is implemented with separate feedback paths for each amplified signal path, then signal quality is improved, but hardware cost and power consumption increase
Solution Approach 1:
The patent merges multiple separate feedback paths into a single shared feedback path that serves multiple amplified signal paths. The feedback signal is obtained from one of the amplified signals and used to update pre-distortion functions for multiple forward data paths, thereby reducing hardware complexity while maintaining signal quality through shared feedback processing.
Solution Approach 2:
The feedback path is designed to be universal, serving multiple functions by providing feedback signals that can update pre-distortion functions for multiple different amplified signal paths. This multi-functional approach allows a single feedback infrastructure to support numerous transmit chains, reducing overall system complexity.
2Measurement precision
If digital predistortion is implemented with separate feedback paths for each amplified signal path, then signal quality is improved, but power consumption increases
Solution Approach 1:
The patent combines multiple feedback processing functions into a single shared feedback path, reducing the total power consumption associated with running multiple separate feedback processing chains. The shared feedback path processes feedback signals that can update multiple pre-distortion functions, thereby lowering overall power usage while maintaining signal quality.
Solution Approach 2:
The system updates pre-distortion functions periodically or on-demand rather than continuously for each path. The feedback mechanism allows for selective updating of pre-distortion functions based on detected signal quality requirements, reducing unnecessary power consumption while maintaining adequate signal quality.
3Measurement precision
If RF power amplifiers operate in the linear region, then signal distortion is reduced, but power efficiency decreases
Solution Approach 1:
The system applies pre-distortion to the input signal before it reaches the RF power amplifier. This preliminary action pre-compensates for the non-linearities of the amplifier, allowing the amplifier to operate in its efficient non-linear region while the overall system output remains linear and undistorted. The pre-distortion function modifies the input signal characteristics to counteract anticipated amplifier distortion.
Solution Approach 2:
The system employs feedback from the amplified signal to continuously monitor and update the pre-distortion function. This feedback mechanism detects distortions introduced by the amplifier and adjusts the pre-distortion parameters accordingly, enabling the amplifier to operate efficiently in its non-linear region while maintaining signal quality through dynamic compensation.
Data Source
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AI summary
Circuitry, method and computer program for reducing distortions in a plurality of amplified signals to be radiated by a multiple antenna system. The circuitry comprising: a plurality of inputs for receiving digital signals for a plurality of forward data paths; routing circuitry for routing the digital signals received at the plurality of inputs to pre-distortion logic for applying a pre-distortion function to each of the signals, the pre-distortion logic being operable to forward each of the signals towards a digital to radio frequency converter and subsequent amplifier for amplifying the signals prior to the signals being radiated; one or more feedback paths each comprising processing logic for comparing a feedback signal generated from one of the amplified signals with a corresponding signal received at one of the inputs to determine a function to be applied by the pre-distortion logic to the input signal; selecting logic for selecting the input signal to be provided with the feedback.