Massive MIMO Pre-Distortion with Shared Feedback Paths
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Solution Overview
Problem
Massive MIMO systems face inefficiencies and hardware costs due to the need for extensive feedback paths to correct nonlinear distortions in RF power amplifiers, which are often stable over time, leading to unnecessary power consumption and hardware requirements.
Innovation Solution
Implementing a dynamic feedback path system where feedback is selectively provided only when necessary, allowing for power-down and sharing of feedback paths, and using flexible routing to reduce hardware and power usage, with pre-distortion functions updated periodically or based on demand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback paths are provided for each amplified signal path in a Massive MIMO system, then distortion correction performance is improved, but hardware cost and power consumption increase significantly
Solution Approach 1:
The patent merges multiple feedback paths into a shared feedback path that serves multiple amplified signal paths. A single feedback path is time-multiplexed across multiple RF chains, allowing the same feedback infrastructure to support distortion correction for multiple antennas without requiring dedicated feedback paths for each antenna, thereby reducing hardware complexity and cost.
Solution Approach 2:
The feedback path is designed to be universal and multi-functional, serving multiple RF chains sequentially through time-division multiplexing. The same feedback path infrastructure is reused across different RF chains at different time intervals, making the system more efficient and reducing the overall number of feedback paths needed in the Massive MIMO system.
2Reliability
If feedback paths are provided for each amplified signal path, then distortion correction is improved, but power consumption increases
Solution Approach 1:
Multiple feedback paths are merged into a single shared feedback path that is time-multiplexed across multiple RF chains. This consolidation reduces the total number of active feedback paths simultaneously, thereby reducing overall power consumption while maintaining distortion correction capability across all RF chains through sequential processing.
Solution Approach 2:
The feedback path operates periodically across different RF chains using time-division multiplexing. Instead of continuously operating multiple feedback paths simultaneously, the system activates a single feedback path in periodic intervals to serve different RF chains, reducing instantaneous and average power consumption while maintaining effective distortion correction.
3Reliability
If RF power amplifiers operate in the linear region, then signal distortion is reduced, but power efficiency decreases
Solution Approach 1:
The system applies preliminary digital pre-distortion to the signal before it reaches the RF power amplifier. By pre-compensating for the expected nonlinear distortions in the digital domain, the amplifier can operate in its more efficient nonlinear region while the pre-distortion ensures that the final transmitted signal maintains the desired linearity and quality, thus achieving both power efficiency and signal quality.
Solution Approach 2:
The system employs feedback paths that sample the output of the RF power amplifier and feed this information back to adjust the pre-distortion parameters. This closed-loop feedback mechanism allows the system to dynamically optimize the pre-distortion function based on actual amplifier behavior, enabling the amplifier to operate efficiently while maintaining signal quality through continuous adaptation.
Data Source
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.