Active Array Antenna Linearization with Shared Feedback
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Solution Overview
Problem
In radio systems with multiple active antenna elements and power amplifiers, existing digital predistortion (DPD) technologies require a separate predistorter and feedback loop for each amplifier, leading to excessive hardware and processing complexity, especially in Active Antenna Systems (AAS) and Multiple Input Multiple Output (MIMO) systems.
Innovation Solution
A radio system architecture that uses a single receive antenna element and a transmit observation receiver to generate a combined reference signal, allowing for the configuration of predistortion parameters for multiple predistorters without the need for individual couplers, thereby reducing hardware and processing complexity, and enabling simultaneous linearization of multiple amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a separate predistorter and feedback loop is implemented for each power amplifier in AAS and MIMO systems, then linearization performance is improved, but hardware complexity and processing requirements increase dramatically
Solution Approach 1:
The patent combines multiple individual feedback loops into a single shared feedback loop that serves all power amplifiers simultaneously. The transmit observation receiver collects combined feedback signals from all antenna branches, and a single adaptor processes these signals to generate predistortion parameters for all predistorters, thereby reducing hardware complexity while maintaining linearization performance.
Solution Approach 2:
The transmit observation receiver and adaptor are designed as universal components that handle feedback signals from multiple power amplifiers simultaneously. The single feedback loop structure can serve all antenna branches in the AAS or MIMO system, making the linearization infrastructure universal rather than dedicated to individual amplifiers.
2Manufacturing precision
If individual feedback loops are used for each amplifier, then distortion cancellation is improved, but signal processing complexity increases
Solution Approach 1:
The patent merges the signal processing functions of multiple individual adaptors into a single adaptor that processes combined feedback signals from all power amplifiers. This single adaptor computes predistortion parameters for all predistorters simultaneously, reducing signal processing complexity while maintaining the ability to cancel distortion from each amplifier.
3Measurement precision
If multiple couplers are implemented for feedback signal extraction, then individual amplifier monitoring is improved, but hardware requirements increase
Solution Approach 1:
The patent eliminates the need for multiple individual couplers by using a single transmit observation receiver that captures the combined feedback signal from all power amplifiers. The adaptor then separates and processes the individual amplifier contributions from this combined signal, reducing hardware requirements while maintaining monitoring capability.
Data Source
AI summary
Systems and methods for linearizing a radio system are disclosed. In some embodiments, a radio system comprises an antenna array, transmit branches comprising respective power amplifiers, a predistortion subsystem comprising predistorters for the transmit branches respectively, a receive antenna element, a transmit observation receiver having an input coupled to the receive antenna element, and an adaptor. The predistorters predistort respective transmit signals to provide predistorted transmit signals to the respective transmit branches for transmission via respective active antenna elements in the antenna array. The transmit observation receiver is operable to receive, via the receive antenna element, a combined receive signal due to coupling between the receive antenna element and the active antenna elements. The adaptor is operable to generate a combined reference signal based on the transmit signals and configure predistortion parameters input to the predistorters based on the combined reference signal and the combined receive signal.