Transmitter Array Beam Shaping and Linearization

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Solution Overview

Problem

Communication systems face challenges in controlling the linear and nonlinear characteristics of transmitter arrays, leading to suboptimal beam shaping and interference management due to the combination of linear and nonlinear power amplifier modes.

Innovation Solution

The solution involves a combination of beam shaping and linearization techniques, where the linear part of the beam is controlled through calibration and the nonlinear part is managed using digital predistortion, with alternating processes until a desired mixture of linear and nonlinear components is achieved, and modifying beam shape coefficients based on error distributions and interference levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If beam shape coefficients are applied to control the linear part of the beam, then beam shaping accuracy is improved, but nonlinear characteristics between transmit paths increase causing beam distortion

Engineering Contradiction:

Improvebeam shaping accuracyVSAvoidnonlinear beam distortion

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The beam is segmented into linear and nonlinear parts, with different control strategies applied to each. Beam shape coefficients control the linear part while digital predistortion handles the nonlinear part, allowing independent optimization of each component.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically adjusts beam shape coefficients and linearization coefficients based on measured error distributions. By changing these parameters iteratively, the system optimizes beam shaping accuracy while compensating for nonlinear distortions.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If digital predistortion is applied to linearize the output, then linearity is improved, but beam shape accuracy deteriorates due to coefficient mismatches

Engineering Contradiction:

Improveoutput linearityVSAvoidbeam shape accuracy

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The system measures error distributions over transmit paths and uses this feedback to iteratively update both beam shape coefficients and linearization coefficients. This closed-loop feedback ensures that linearity improvement through predistortion does not compromise beam shape accuracy.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

Digital predistortion is applied in advance to compensate for expected nonlinearities before they affect the beam shape. By pre-correcting the signal, the system maintains both linearity and beam shape accuracy.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If calibration is performed to improve beam shape coefficients, then beam shaping is improved, but the process time increases due to iterative measurement and adjustment

Engineering Contradiction:

Improvebeam shape coefficient accuracyVSAvoidcalibration time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The calibration process uses periodic iteration between linearization and calibration steps, alternating until convergence is achieved. This structured periodic approach efficiently reaches optimal coefficients without unnecessary iterations.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system replaces extensive manual measurement and adjustment with automated digital measurement of error distributions and algorithmic coefficient optimization. This substitution of mechanical calibration processes with digital computation significantly reduces calibration time.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Adaptability or versatility

If nonlinear characteristics are increased between transmit paths, then beam forming flexibility is improved, but interference management worsens due to increased nonlinear distortion

Engineering Contradiction:

Improvebeam forming flexibilityVSAvoidinterference from nonlinear distortion

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The system converts harmful nonlinear distortion into a beneficial tool for beam forming flexibility. By deliberately introducing and then compensating for nonlinear characteristics through digital predistortion, the system achieves flexible beam forming while eliminating interference from nonlinear distortion.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS10841018B2Communication system

Publication Date: 2020.11.17 NOKIA TECHNOLOGIES OY

AI summary

An apparatus comprising means for: applying beam shape coefficients for obtaining a beam shape output for a linear part of the beam formed by an array of transmitters, each transmitter being associated with a respective transmit path comprising a respective power amplifier; varying the output characteristics of at least one transmit path to increase nonlinear characteristics between the transmit paths to provide a beam shape for a non-linear part of the beam; linearizing the output of the array by: determining linearization coefficients for the array for digitally predistorting the input signal to the array; and applying the linearization coefficients to the signal input to the array; and calibrating the transmitter array by: measuring error distributions over at least two transmit paths; modifying the beam shape coefficients to better obtain the beam shapes subsequent to the linearization; and applying the modified beam shape coefficients to the array of transmitters.