ONU PSync Detection Across OLT Bit-Interleaving Modes

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Solution Overview

Problem

Existing optical network units (ONUs) in passive optical networks (PONs) lack the ability to detect whether an Optical Line Terminal (OLT) has implemented non-interleaving or bit-interleaving when formulating downstream signals, leading to synchronization issues due to the inability of current synchronization state machines to accommodate OLT-configurable bit interleaving.

Innovation Solution

The ONU searches for a physical synchronization sequence (PSync) pattern in all possible alignments for all possible OLT bit-interleaving modes within the downstream signal to determine the interleaving mode used by the OLT, transitioning to a pre-synchronization state once the pattern is found, enabling synchronization and correct deinterleaving processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the ONU uses a fixed synchronization state machine, then the device complexity is low, but it cannot accommodate OLT-configurable bit interleaving modes

Engineering Contradiction:

Improveaccommodation of OLT-configurable bit interleaving modesVSAvoidsynchronization state machine complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The synchronization state machine is designed to dynamically adapt to different OLT-configurable bit interleaving modes (non-interleaving, 2x bit-interleaving, 4x bit-interleaving, 8x bit-interleaving) by automatically detecting the PSync pattern at different alignments and switching between corresponding deinterleaving modes, rather than using a fixed state machine

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The synchronization state machine performs multiple functions by handling different interleaving modes through a unified structure that searches for PSync patterns across all possible alignments and modes, making it universally applicable to any OLT configuration without requiring separate dedicated state machines for each mode

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If the ONU searches for PSync pattern in all possible alignments and modes, then the synchronization reliability is improved, but the time required for synchronization increases

Engineering Contradiction:

Improvesynchronization reliabilityVSAvoidsynchronization time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The ONU performs preliminary actions by searching for the PSync pattern in all possible alignments and interleaving modes during the synchronization process, establishing the correct synchronization state before normal data reception begins, which ensures reliable synchronization even when the OLT uses uncommon interleaving configurations

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250392848A1Downstream Synchronization State Machine for Optical Line Terminal (OLT)-Configurable Bit Interleaving in High-Speed Passive Optical Networks (PONs)

Publication Date: 2025.12.25 HUAWEI TECH CO LTD

AI summary

A method implemented by an optical network unit (ONU) in a passive optical network (PON). The method includes receiving an encoded downstream (DS) signal from an optical line terminal (OLT), searching for a physical synchronization sequence (PSync) pattern in all possible alignments for all possible OLT bit-interleaving modes within the downstream signal, and transitioning to a pre-synchronization state once the PSync pattern has been found.