Shared Digital Predistortion for Multi-Branch AAS Linearization
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Solution Overview
Problem
Advanced Antenna Systems (AAS) with multiple active transmitter branches face challenges in digital predistortion due to increased complexity, hardware resource requirements, and the need for separate linearizers for each branch, leading to degraded processing power, capacity, and efficiency, especially in analog beamforming systems where direct access to individual power amplifier inputs is not possible.
Innovation Solution
A low-complexity digital predistortion (DPD) system that uses a single DPD subsystem to predistort a baseband signal based on an adaptation model, applying gain and phase adjustments to multiple transmit branches, and processes combined receive signals to update the model, reducing the need for individual couplers and linearizers, and enabling efficient linearization of multiple power amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate linearizers are used for each transmitter branch in AAS, then linearization performance is improved, but device complexity and hardware cost increase dramatically
Solution Approach 1:
The patent combines multiple separate linearizers into a single shared linearizer that serves all transmitter branches. The linearized signals from multiple branches are combined at a common point, eliminating the need for individual linearizers per branch while maintaining overall linearization performance through coordinated processing.
Solution Approach 2:
The shared linearizer is designed to perform linearization for multiple transmitter branches simultaneously. A single linearizer unit processes signals from all branches, making the hardware universal and multi-functional rather than dedicated to a single branch, thereby reducing overall hardware complexity.
2Reliability
If processing power is allocated to linearizers in AAS, then linearization capability is improved, but processing power for other functionality and traffic capacity deteriorate
Solution Approach 1:
By merging multiple linearizer processing functions into a single shared linearizer, the total processing power required for linearization is reduced. This frees up processing resources that can be reallocated to other functionalities and traffic handling, improving overall system productivity while maintaining linearization capability.
3Adaptability or versatility
If more transmitter branches are added to AAS, then antenna system capability is improved, but the complexity of linearizing all transmission paths grows dramatically
Solution Approach 1:
The shared linearizer is designed with universal functionality to handle linearization for any number of transmitter branches. Instead of adding a dedicated linearizer for each new branch, the existing shared linearizer processes signals from all branches, making the system scalable without proportionally increasing linearization complexity.
4Measurement precision
If individual couplers are added for each transmitter branch to enable feedback, then DPD adaptation is improved, but hardware space and coupling interference increase
Solution Approach 1:
The patent merges multiple individual coupler functions into a single shared coupler that collects feedback signals from all transmitter branches. This eliminates the need for separate couplers for each branch, reducing hardware space requirements while maintaining the ability to perform DPD adaptation through the combined feedback path.
Data Source
AI summary
Systems and methods are disclosed herein that provide low-complexity Digital Predistortion (DPD) for a transceiver system that uses an Advanced Antenna System (AAS) to provide analog or hybrid beamforming.