Optical Network Unit Upstream Frequency Shifting

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Solution Overview

Problem

Conventional passive optical networks (PONs) face inefficiencies due to latency and resource wastage in upstream data transmission, particularly in asymmetric bandwidth scenarios, where downstream bandwidth is fixed and upstream resources are underutilized, leading to transmission delays and complex implementation.

Innovation Solution

A method for an optical network unit that adjusts light signals to specific wavelengths for upstream communication, allowing for efficient asymmetric data processing by demodulating incoming signals, mixing with an oscillator-generated signal, and modulating the light signal using a software radio to shift the upstream frequency, enabling flexible bandwidth allocation and improved signal quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional PONs use electronic processing with buffering and scheduling for upstream data transmission, then bidirectional communication is enabled, but transmission latency increases and throughput degrades

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidtransmission latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces electronic processing and buffering systems with optical domain processing. By performing demodulation, mixing, and modulation directly in the optical domain using optical heterodyne detection and software-defined radio, the system eliminates electronic conversion stages that cause latency, thereby reducing transmission delay while maintaining communication reliability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an optical local oscillator as an intermediary element in the optical domain to enable frequency shifting and signal processing without converting to electronic domain. This optical intermediary allows direct optical processing that avoids the latency associated with electronic buffering and scheduling

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If NGOA systems provide symmetric bandwidth in upstream and downstream directions, then high data rates are achieved, but resources are wasted when asymmetric bandwidth profile is required

Engineering Contradiction:

Improvedata rateVSAvoidresource wastage

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent implements dynamic bandwidth allocation in the optical domain where the upstream receiver can dynamically adjust its processing capacity and frequency allocation based on actual traffic demands. This dynamic adaptation allows the system to allocate resources efficiently according to asymmetric bandwidth requirements, avoiding the resource wastage inherent in fixed symmetric configurations

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent enables parameter changes in the optical domain by allowing flexible adjustment of upstream frequency offsets and bandwidth allocation through software-controlled optical processing. This permits the system to adapt bandwidth parameters dynamically to match asymmetric traffic patterns, optimizing resource utilization while maintaining high data rates

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If GPON systems implement dynamic bandwidth allocation in upstream direction, then asymmetric bandwidth profile is supported, but transmission delays amount to 20-100 ms and protocol complexity increases

Engineering Contradiction:

Improvebandwidth allocation flexibilityVSAvoidprotocol implementation complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces complex electronic protocol processing with simplified optical domain processing. By performing demodulation, frequency mixing, and signal separation directly in the optical domain, the system reduces protocol complexity while maintaining bandwidth allocation flexibility, eliminating the need for complex electronic buffering and scheduling mechanisms

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent segments the signal processing functions into distinct optical components (demodulator, mixer, local oscillator, modulator) that operate independently in the optical domain. This segmentation simplifies the overall protocol implementation by allowing each component to handle specific tasks without requiring complex coordination, thereby reducing device complexity while preserving adaptability

Inventive Principle:

Principle #1Segmentation

4Productivity

If upstream transmitters of ONUs are switched on and off due to time-domain multiplexing, then bandwidth sharing is achieved, but dynamic requirements at the upstream receiver increase

Engineering Contradiction:

Improvebandwidth utilization efficiencyVSAvoidreceiver dynamic requirements

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces time-domain switching with optical frequency-domain multiplexing. By assigning different optical frequencies to different ONUs and using optical filtering at the receiver, the system achieves bandwidth sharing without the need for rapid switching, thereby reducing the dynamic requirements and complexity of the upstream receiver while maintaining efficient bandwidth utilization

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 reduces hardware complexity and costs, allows for efficient asymmetric bandwidth allocation, and increases power budget, enabling high bandwidth efficiency and supporting both symmetrical and asymmetrical optical access systems, while maintaining compatibility with GPON systems.

Implementation Method 1

adjusting a light signal to a wavelength or wavelength range indicated by the configuration information

Methodology Applied

Scientific EffectWavelength adjustment:

Implementation Method 2

demodulating an incoming optical signal by means of the light signal

Methodology Applied

Scientific EffectOptical demodulation:

Implementation Method 3

mixing the demodulated incoming optical signal with a signal generated by an oscillator and generating a modulated optical upstream signal

Methodology Applied

Scientific EffectFrequency mixing: Heterodyne

Implementation Method 4

modulating the light signal by means of a software radio, so that the resulting optical upstream frequency can be shifted

Methodology Applied

Scientific EffectOptical modulation: Phase Modulation

Data Source

PatentUS10305596B2Data processing of an optical network element

Publication Date: 2019.05.28 XIEON NETWORKS SARL

AI summary

A method for data processing of an optical network unit is provided, the method comprising the steps of receiving a configuration information at the optical network unit, adjusting a light signal to a wavelength or wavelength range indicated by the configuration information, demodulating an incoming optical signal by means of the light signal, mixing the demodulated incoming optical signal with a signal generated by an oscillator and generating a modulated optical upstream signal modulating the light signal by means of a software radio, so that the resulting optical upstream frequency can be shifted with respect to the frequency of the local oscillator by a programmable amount. Furthermore, an according device and a communication system are suggested comprising at least one such device.