Beamforming Front End Pre-Distortion for Multi-Path Linearity
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Solution Overview
Problem
Existing RF communication systems face challenges in achieving high linearity in beamforming communication systems, particularly due to variations in distortion responses among multiple transmit signal paths.
Innovation Solution
The implementation of a mobile device with a baseband processor that provides digital pre-distortion and a front end system with multiple transmit signal paths, each capable of analog pre-distortion, to compensate for differences in distortion responses and enhance linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If digital pre-distortion is applied in the baseband processor, then linearity correction is improved, but device complexity increases
Solution Approach 1:
The pre-distortion function is segmented into two independent parts: digital pre-distortion in the baseband processor and analog pre-distortion in the front end system. This segmentation allows each part to handle specific aspects of linearity correction, with digital pre-distortion providing coarse correction and analog pre-distortion providing fine correction, thereby improving overall linearity while distributing complexity across different subsystems
Solution Approach 2:
Digital pre-distortion is applied preliminarily in the baseband processor before the signal reaches the front end system. This preliminary digital correction prepares the signal by compensating for major distortion characteristics, reducing the burden on subsequent analog pre-distortion circuits and overall system complexity
2Manufacturing precision
If analog pre-distortion is provided to multiple transmit signal paths, then linearity is improved, but device complexity increases
Solution Approach 1:
Analog pre-distortion is applied locally to each transmit signal path individually, allowing each path to be optimized for its specific distortion characteristics. Each transmit signal path receives tailored analog pre-distortion correction, compensating for path-specific variations in phase and gain distortion, thereby improving overall system linearity
Solution Approach 2:
The analog pre-distortion circuitry is designed with multi-functionality to serve multiple transmit signal paths. The same analog pre-distortion architecture and control mechanism are universally applied across all transmit paths, reducing the need for completely separate correction circuits for each path and thereby limiting the increase in device complexity
3Manufacturing precision
If separate analog pre-distortion is applied to each transmit signal path, then distortion compensation is improved, but ease of operation deteriorates
Solution Approach 1:
The system employs feedback mechanisms where observation data from multiple transmit signal paths is collected and used to generate settings for digital pre-distortion. This feedback loop automatically adjusts pre-distortion parameters based on actual measured distortion, compensating for variations across transmit paths without requiring manual calibration, thereby maintaining ease of operation
Solution Approach 2:
The system performs self-calibration and self-correction by automatically generating pre-distortion settings based on observation data from the transmit paths themselves. The system uses its own operational data to configure the pre-distortion parameters, eliminating the need for external manual adjustment and maintaining ease of operation despite per-path customization
Data Source
AI summary
Beamforming communication systems with high linearity are provided. In certain embodiments, a method of beamforming includes generating a transmit signal using a baseband processor, providing digital pre-distortion to the transmit signal, generating a radio frequency input signal based on the transmit signal using a transceiver, processing the radio frequency input signal to generate a plurality of radio frequency output signals using a plurality of transmit signal paths of a front end system, providing analog pre-distortion to at least one of the plurality of transmit signal paths using the front end system, and radiating a transmit beam in response to receiving the plurality of radio frequency output signals using an antenna array.