Optical Network Data Synchronization via Joint Framer Index Estimation

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Solution Overview

Problem

Data transmitted across optical communication networks face interference and synchronization issues due to incorrect frame estimation, leading to processing delays and inefficiencies.

Innovation Solution

Implementing a method for joint estimation of the framer index and frequency offset in optical communication systems by generating a pseudo-random sequence of symbols, interleaving them with payload symbols, and using a sliding window for cross-correlation to synchronize data transmission and reception.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional data transmission methods are used in optical communication networks, then the system structure remains simple, but synchronization issues and interference make data processing difficult

Engineering Contradiction:

Improvedata synchronization accuracyVSAvoidreceiver structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by inserting a known pseudo-random sequence (PRS) into the transmitted data stream before transmission. This pre-placed sequence enables the receiver to perform cross-correlation analysis to accurately determine frame boundaries and synchronization parameters without requiring complex real-time estimation algorithms, thus improving synchronization reliability while keeping receiver structure relatively simple

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses a pseudo-random sequence as an intermediary element that mediates between the transmitted data and the receiver's processing requirements. This PRS acts as a synchronization marker that simplifies the receiver's task of identifying frame boundaries and estimating timing parameters, transforming a complex synchronization problem into a simpler pattern recognition task through cross-correlation

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If joint estimation of framer index and frequency offset is implemented, then synchronization accuracy is improved, but processing time increases

Engineering Contradiction:

Improveframe boundary detection accuracyVSAvoidprocessing delay

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces complex iterative estimation algorithms with a more efficient cross-correlation-based approach. By transforming the synchronization problem into a pattern matching task using the known pseudo-random sequence, the system achieves accurate frame boundary detection through computational methods that are faster and less time-consuming than traditional mechanical or iterative estimation techniques

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the approach by transforming the synchronization problem from estimating multiple parameters simultaneously (framer index and frequency offset) to detecting a known pattern (pseudo-random sequence) through cross-correlation. This parameter transformation enables more efficient processing while maintaining high measurement precision for frame boundary detection

Inventive Principle:

Principle #35Parameter changes

3Productivity

If multiple subcarriers are used for data transmission, then data capacity increases, but chromatic dispersion effects worsen synchronization

Engineering Contradiction:

Improvedata transmission capacityVSAvoidchromatic dispersion impact

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies segmentation by treating each subcarrier independently for synchronization purposes. The pseudo-random sequence is replicated across multiple subcarriers, allowing the receiver to perform separate cross-correlation analysis on each subcarrier. This segmentation approach enables the system to maintain synchronization accuracy even in the presence of chromatic dispersion, which affects different subcarriers differently, while still benefiting from the increased capacity provided by multiple subcarriers

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS20250211337A1Data synchronization in optical networks and devices

Publication Date: 2025.06.26 INFINERA CORP

AI summary

Joint estimation of the framer index and the frequency offset in an optical communication system are described among various other features. A transmitter can transmit data frames using pilot and framer symbols. A receiver can estimate the framer index and frequency offset using the pilot and framer symbols, and identify the beginning of a header portion of a data frame. The estimation can be performed to compensate for delays such as half-symbol delays and differential group delays. By identifying the beginning of the header portion of a data frame while compensating for certain delays, the receiver can synchronize, with less error, the data transmitted by the transmitter and the data it received.