Externally Synchronized OTN Elements for Jitter Control
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Solution Overview
Problem
OTN multiplexing systems face limitations in network synchronization, leading to excessive jitter and wander noise accumulation, which exceeds acceptable levels for network operators, especially when concatenated across multiple spans, and do not support 100% bit-transparent multiplexing of lower-rate signals like Gigabit Ethernet and T1/T3 without proprietary and non-standard solutions.
Innovation Solution
The introduction of external synchronization for OTN network elements to generate standardized optical transmission units, providing stratum-level synchronization, rate adapters for scaling, and multiple external timing sources to reduce jitter and wander noise, along with automated timing protection switching for redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If OTN multiplexing is used without external synchronization, then device complexity is reduced and ease of manufacture is improved, but jitter and wander noise accumulate to excessive levels
Solution Approach 1:
The patent introduces an external synchronization source as an intermediary element that provides a reference clock signal to all OTN network elements. This mediator enables coordinated timing across the network without requiring complex internal synchronization mechanisms in each device, thus maintaining ease of manufacture while effectively controlling jitter and wander noise accumulation.
2Productivity
If multiple concatenated OTN multiplexers are deployed without synchronization, then network capacity and productivity are increased, but jitter and wander noise exceed acceptable levels
Solution Approach 1:
The patent implements a feedback mechanism where each OTN network element receives synchronization information from external sources and uses it to adjust its timing operations. This feedback loop prevents the cumulative buildup of jitter and wander noise that would otherwise occur in concatenated multiplexer configurations, enabling high network capacity while maintaining signal quality within acceptable limits.
3Object-affected harmful factors
If external synchronization is added to OTN network elements, then jitter and wander noise are reduced, but device complexity increases
Solution Approach 1:
The patent segments the synchronization function into a separate external synchronization source that is independent of the main OTN multiplexer functionality. This allows the core multiplexing devices to remain relatively simple while the complexity of synchronization management is handled by dedicated external synchronization network elements, thus reducing jitter and wander noise without significantly increasing the complexity of individual multiplexers.
Data Source
AI summary
The present invention utilizes external synchronization to generate a completely standardized or functionally standardized optical transmission unit of level k (OTUk[V]) signal providing less jitter and wander build-up through a network of optical transport network (OTN) elements. This increases noise margins of transported signals and payloads. The present invention provides stratum-level synchronization utilizing a standards-based approach. In one embodiment of the present invention, rate adapters are included to provide m/n scaling of OTUk[V] signals to rates common in SONET and SDH synchronizers to provide line and loop distribution of timing through OTUk[V] signals. The present invention provides a choice of external synchronization sources including building integrated timing source (BITS), line, and loop timing sources. In another exemplary embodiment, the present invention provides multiple external references and automated timing protection switching for redundancy and reliability.