Optical Beamforming for Carrier Aggregation

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Solution Overview

Problem

Existing beamforming technologies face challenges in combining optical beamforming with carrier aggregation, especially interband carrier aggregation, due to frequency selectivity issues, which require duplication of electrical circuits for each supported frequency, and are sensitive to oscillator phase noise and signal leakage at higher frequencies.

Innovation Solution

The solution involves a beamforming device and method using a laser light source with a distribution unit to distribute wavelengths onto optical paths, where a wavelength selection device introduces phase shifts and a heterodyning device generates signals for phased array antennas, allowing for optical beamforming without duplicating beamforming circuits for each frequency, by selecting subsets of optical frequencies and modulating them to produce desired radio frequencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electrical beamforming circuits are used at higher frequencies, then beamforming functionality is achieved, but sensitivity to oscillator phase noise and signal leakage increases

Engineering Contradiction:
Improvebeamforming stabilityVSAvoidoscillator phase noise and signal leakage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces electrical beamforming circuits with optical beamforming circuits. The optical domain is used to generate and distribute phase-shifted signals to antenna elements, eliminating the harmful effects of electrical oscillator phase noise and signal leakage that plague high-frequency electrical circuits. The optical light source and optical modulators provide stable phase references without the frequency-dependent issues of electrical oscillators.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an optical domain as an intermediary between the baseband signal processing and the RF antenna transmission. Optical signals serve as a mediator to carry beamforming phase information without being subject to the same phase noise and leakage problems as direct electrical RF circuits. The optical-to-RF conversion happens at each antenna element, isolating the sensitive beamforming phase control from the problematic high-frequency electrical domain.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If electrical circuits are duplicated for each frequency in carrier aggregation, then multiple frequency support is achieved, but device complexity and cost increase

Engineering Contradiction:
Improvecarrier aggregation supportVSAvoidcircuit duplication
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a universal optical beamforming circuit that can serve multiple frequency bands simultaneously. A single optical light source and optical distribution network provide beamforming functionality for all carrier aggregation frequencies. The system uses wavelength division multiplexing to carry multiple frequency components through a shared optical infrastructure, eliminating the need to duplicate electrical beamforming circuits for each frequency band.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent transitions from frequency-domain multiplexing in the electrical domain to wavelength-domain multiplexing in the optical domain. By using different optical wavelengths to represent different RF frequency components, the system achieves carrier aggregation support without duplicating the physical beamforming circuitry. The optical wavelength dimension provides an additional degree of freedom for multiplexing that doesn't exist in the electrical RF domain.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Object-affected harmful factors

If optical beamforming is implemented, then noise and signal leakage are reduced, but device complexity increases due to optical components

Engineering Contradiction:
Improvenoise and signal leakageVSAvoidoptical component integration
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the optical beamforming functionality directly with the existing antenna element structure. The optical modulators are integrated at or near each antenna element, combining the optical signal generation with the RF transmission path. This integration approach reduces the overall system complexity by eliminating separate optical-to-electrical conversion stages and shared distribution networks that would otherwise be required.

Inventive Principle:
Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables efficient optical beamforming and carrier aggregation without the need for duplicating beamforming circuits, reducing noise and signal leakage, and allowing for precise control of beam direction and frequency, thus improving performance in high-frequency applications.

Implementation Method 1

a heterodyning device configured to generate a signal for transmission by an element of the phased array antenna, wherein the heterodyning device is configured to heterodyne a plurality of selected spectral components of the spaced wavelengths of the laser light source

Methodology Applied
Scientific EffectHeterodyning: Heterodyne

Implementation Method 2

One or more phase shift unit connected to a said wavelength selection device, wherein the phase shift unit is configured to introduce a phase shift to a received wavelength

Methodology Applied
Scientific EffectPhase shift:

Data Source

PatentEP3317982B1Optical beamforming
Publication Date: 2019.12.11 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3317982B1 patent drawingFigure 1
  • EP3317982B1 patent drawingFigure 2a~4b
  • EP3317982B1 patent drawingFigure 5

AI summary

A beamforming device for a phased array antenna, comprising: a laser light source (2) arranged to provide an optical spectrum comprising a plurality of spaced wavelengths, and a distribution unit (4) configured to distribute one or more of the plurality of spaced wavelengths onto a plurality of optical paths (6). A wavelength selection device (8) configured to receive the plurality of spaced wavelengths on each of the plurality of optical paths. One or more phase shift unit (12) connected to a said wavelength selection device, wherein the phase shift unit is configured to introduce a phase shift to a received wavelength. The wavelength selection device on each optical path is configured to selectively transmit a wavelength to the phase shift unit. The wavelength selection device is configured to receive the said phase shifted wavelength from the phase shift unit (12). The beamforming device further comprising a heterodyning device (16) configured to generate a signal for transmission by an element of the phased array antenna, wherein the heterodyning device is configured to heterodyne a plurality of selected spectral components of the spaced wavelengths of the laser light source.