Multi-Antenna Power Amplifier Linearization for Spatial Emission Control
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Solution Overview
Problem
Multi-antenna wireless communication systems face challenges in reducing spatial emissions, leading to adjacent channel leakage and interference with critical systems at adjacent frequencies, especially due to power amplifier nonlinearity.
Innovation Solution
The implementation of digital pre-distortion (DPD) and analog pre-distortion techniques to linearize power amplifiers, minimizing spatial emissions by adjusting radiation patterns and reducing adjacent channel leakage ratio (ACLR) in both azimuth and elevation directions, allowing Active-Array Antenna Systems (AAS) to coexist with other systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power amplifiers are operated at high power levels to meet data demand, then transmission power is improved, but spatial emissions and adjacent channel leakage increase
Solution Approach 1:
The patent applies pre-distortion techniques (digital and analog) to the input signal before it reaches the power amplifier. This preliminary action pre-compensates for the nonlinearities that will occur during high-power amplification, thereby reducing spatial emissions and adjacent channel leakage while maintaining high transmission power levels.
Solution Approach 2:
The patent modifies the signal parameters by applying distortion compensation algorithms that adjust the amplitude and phase characteristics of the input signal. This parameter transformation allows the power amplifier to operate in a more linear region, reducing harmful emissions while preserving transmission power.
2Object-generated harmful factors
If pre-distortion techniques are applied to linearize power amplifiers, then spatial emissions are reduced, but device complexity increases
Solution Approach 1:
The patent divides the pre-distortion function into separate digital and analog stages. The digital pre-distortion handles coarse compensation while the analog pre-distortion refines the linearization. This segmentation allows each stage to be optimized independently and simplifies the overall implementation complexity.
Solution Approach 2:
The patent introduces an intermediate signal processing stage that bridges the baseband and RF domains. This intermediary pre-distortion block provides a transition point where nonlinear compensation can be applied without directly complicating the power amplifier design, thereby managing system complexity.
3Object-generated harmful factors
If radiation patterns are adjusted to minimize spatial emissions, then adjacent channel leakage ratio is improved, but beamforming capability is degraded
Solution Approach 1:
The patent applies pre-distortion to the signal before beamforming and spatial transmission. This preliminary linearization ensures that the radiation pattern adjustments for beamforming do not introduce additional nonlinear distortions, thereby maintaining both low adjacent channel leakage and effective beamforming capability.
Solution Approach 2:
The patent transforms the signal parameters through pre-distortion compensation, which preserves the amplitude and phase relationships necessary for beamforming while reducing the nonlinear effects that cause adjacent channel leakage. This parameter transformation maintains beamforming integrity.
Data Source
AI summary
Facilitating the reduction and/or mitigation of spatial emissions in a multi antenna wireless communications system is provided herein. A system can comprise a memory that stores executable instructions that, when executed by a processor, facilitate performance of operations that can comprise applying a first signal linearization to a first output signal of a first power amplifier based on a determination that an adjacent channel leakage ratio of the first output signal of the first power amplifier fails to satisfy a defined output value. The operations can also comprise applying a second signal linearization to a group of output signals of a group of power amplifiers for a defined azimuth direction associated with channel frequencies of the group of output signals and applying a third signal linearization to the group of output signals for a defined elevation direction associated with the channel frequencies of the group of output signals.