Artificial Justifications for Clock Phase Noise Shaping

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Solution Overview

Problem

In Optical Transport Networks (OTNs), asynchronous mapping techniques lead to low frequency phase variations in the recovered client clock due to rare use of justifications, causing jitter and wander, which are difficult to filter and result in buffer overflow or underflow.

Innovation Solution

Intelligent artificial justifications are created to shape phase variations, increasing their frequency so they can be easily filtered, improving the accuracy of the recovered client clock by noise shaping the quantization noise introduced by actual justifications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If asynchronous mapping techniques are used to map client data to frames, then mapping flexibility and adaptability are improved, but low frequency phase variations and jitter are introduced in the recovered client clock

Engineering Contradiction:

Improvemapping flexibilityVSAvoidclock stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent converts the harmful low-frequency phase variations introduced by asynchronous mapping into beneficial high-frequency variations through artificial justifications. By strategically introducing artificial justifications with specific patterns, the system transforms the quantization noise from a harmful low-frequency signal into a beneficial high-frequency signal that can be easily filtered out, thereby improving clock recovery accuracy while maintaining mapping flexibility.

Inventive Principle:

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

Solution Approach 2:

The patent changes the frequency parameter of phase variations from low-frequency to high-frequency by introducing artificial justifications. This parameter transformation allows the phase variations to move from a difficult-to-filter low-frequency range into a high-frequency range where they can be effectively removed by standard filtering techniques, thus resolving the contradiction between mapping flexibility and clock stability.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If justifications are rarely used in asynchronous mapping, then buffer overflow and underflow are prevented, but low frequency phase variations cause jitter and wander that are difficult to filter

Engineering Contradiction:

Improvebuffer managementVSAvoidfiltering difficulty

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent takes the harmful low-frequency phase variations caused by rare justifications and converts them into beneficial high-frequency variations through artificial justifications. This transformation makes the previously difficult-to-filter variations easily filterable, while the rare use of justifications continues to prevent buffer overflow and underflow conditions.

Inventive Principle:

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

Solution Approach 2:

The patent introduces artificial justifications that create high-frequency phase variations analogous to mechanical vibrations. These high-frequency variations are much easier to filter than low-frequency variations, effectively removing the jitter and wander caused by rare justifications while maintaining the buffer protection benefits.

Inventive Principle:

Principle #18Mechanical vibration

3Measurement precision

If actual justifications are used to map client data, then mapping accuracy is maintained, but quantization noise introduces phase variations that are difficult to filter

Engineering Contradiction:

Improvemapping accuracyVSAvoidquantization noise

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful quantization noise generated by actual justifications into beneficial high-frequency phase variations through artificial justifications. The artificial justifications are designed to shape the noise spectrum, pushing the quantization noise to higher frequencies where it becomes easily filterable, thus maintaining mapping accuracy while eliminating the harmful low-frequency phase variations.

Inventive Principle:

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

Solution Approach 2:

The patent changes the frequency parameter of quantization noise from low-frequency to high-frequency through the introduction of artificial justifications. This parameter change transforms the noise from a difficult-to-filter low-frequency signal into a high-frequency signal that can be effectively removed by standard filtering techniques, thereby maintaining mapping precision while eliminating harmful noise factors.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9729245B2Using artificial justifications to apply noise shaping to actual justifications associated with mapping client data

Publication Date: 2017.08.08 INFINERA CORP

AI summary

A transmitter may receive client data, associated with a client rate, to be mapped to frames associated with a server rate. The transmitter may generate justifications associated with the mapping of the client data to the frames. The transmitter may create, based on the justifications, artificial justifications that include information associated with justifications created to shape phase variations present in a recovered client clock associated with the client rate. The phase variations may be shaped based on the artificial justifications to cause shaped phase variations to be present in the recovered client clock. The shaped phase variations may include phase variations that can be filtered from the recovered client clock. The transmitter may map the client data to the frames based on the artificial justifications to cause the shaped phase variations to be present in the recovered client clock.