Subsea Optical Transmitter Dynamic Modulation Adjustment

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Solution Overview

Problem

Subsea optical communication systems face challenges in efficiently managing signal power and noise due to long-term fiber loss and repeater pump failures, leading to underutilization of power budget margins and reduced data throughput, especially since traditional systems lack automatic gain control mechanisms and are not optimized for varying water depths and aging.

Innovation Solution

Implementing probabilistic constellation shaping and dynamic modulation mode adjustment, enabled by a control circuit with artificial intelligence, to adjust data rate and capacity in finer granularity, utilizing excess and repair margins to maintain optimal transmission performance despite aging and repairs, and automate modulation format changes to maximize data throughput.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traditional fixed modulation formats are used, then system design is simple, but data throughput is underutilized due to excessive power budget margins

Engineering Contradiction:

Improvedata throughputVSAvoidmodulation format management

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent implements dynamic modulation format adjustment by transitioning from fixed modulation formats to variable formats that adapt to real-time link conditions. The system monitors power budget margins and automatically adjusts modulation formats (e.g., from QPSK to 16-QAM or 64-QAM) to maximize data throughput while maintaining transmission reliability, thereby resolving the contradiction between simple system design and underutilized productivity.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of modulation format from static to dynamic based on power budget margin conditions. By monitoring link quality metrics and adjusting spectral efficiency parameters in real-time, the system optimizes data throughput without requiring complete system redesign, thus improving productivity while managing complexity through parameter-based adaptation.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If large power budget margins are allocated for repairs and aging, then transmission reliability is maintained, but data throughput is reduced due to unused capacity

Engineering Contradiction:

Improvetransmission reliabilityVSAvoiddata throughput

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent implements a feedback mechanism that continuously monitors link conditions, power budget margins, and transmission performance. Based on this feedback, the system dynamically adjusts modulation formats to maintain reliability thresholds while maximizing throughput. This resolves the contradiction by using feedback loops to balance reliability requirements with productivity optimization, ensuring that power budget margins are utilized effectively rather than leaving capacity unused.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies partial action by adjusting modulation formats to use only the necessary power budget margin required for reliable transmission, rather than consistently using excessive margins. This allows the system to maintain transmission reliability while capturing and utilizing the previously wasted capacity for increased data throughput, effectively resolving the contradiction between reliability and productivity.

Inventive Principle:

Principle #16Partial or excessive action

3Power

If uniform probability distribution is used for constellation points, then modulation implementation is simple, but signal power to noise power ratio is insufficient compared to Shannon limit

Engineering Contradiction:

Improvesignal power to noise power ratioVSAvoidconstellation probability distribution

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent changes the probability distribution parameter of constellation points from uniform to non-uniform distribution. By assigning different probabilities to different constellation points based on their distance from the origin and susceptibility to noise, the system improves signal power to noise power ratio and approaches the Shannon limit. This parameter change resolves the contradiction by optimizing power efficiency while managing complexity through mathematical modeling of probability distributions.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11483075B2Telecommunication system having a modulation format based upon degradation predictions

Publication Date: 2022.10.25 INFINERA CORP

AI summary

A transmitter block, comprising an optical source, a modulator, a transmission circuit and a control circuit. The optical source has a laser providing an optical signal. The modulator is configured to encode data into the optical signal using an m-quadrature amplitude modulation format. The transmission circuit has circuitry to receive data to be encoded into the optical signal. The transmission circuit has at least one drive circuit supplying driver signals to the modulator to cause the modulator to encode data into the optical signal using the m-quadrature amplitude modulation format. The control circuit supplies control signals to the transmission circuit to cause the transmission circuit to change the m-quadrature amplitude modulation format from a first m-quadrature amplitude modulation format to a second m-quadrature amplitude modulation format based upon predicted degradation of a link to receive modulated data from the modulator.