Random Channel Assignment in WDM Passive Optical Networks
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Solution Overview
Problem
Conventional WDM-PON networks require wavelength-selected ONUs, making them difficult to manage and prone to errors, and necessitate PON reconstruction, as they rely on wavelength-independent power splitters and WDM devices.
Innovation Solution
Implementing a random channel assignment system for ONUs, allowing each ONU to transmit virtually any wavelength band, eliminating the need for wavelength selection and using a 'selectionless ONU' scheme where receivers adjacent to each other can receive signals across overlapping sensitivity wavebands, enabling efficient upstream signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wavelength-selected ONUs are used in conventional WDM-PON networks, then each ONU can be assigned a unique wavelength channel, but the network becomes difficult to manage and prone to errors, requiring PON reconstruction
Solution Approach 1:
The invention makes ONUs universal by removing wavelength-specific hardware requirements. Each ONU can transmit on any wavelength channel through the use of broadband lasers and WDM multiplexers at the OLT, eliminating the need for wavelength-selected ONUs and their associated management complexity
Solution Approach 2:
The invention extracts the wavelength selection function from the ONU side and relocates it to the OLT side. The OLT now performs wavelength assignment dynamically through software control, while ONUs use generic broadband components, separating the complexity of wavelength management from the field-deployed ONU devices
2Area of stationary object
If wavelength-independent power splitters are used with WDM devices, then network coverage can be maximized, but PON reconstruction is required which increases deployment cost and complexity
Solution Approach 1:
The invention introduces dynamic wavelength assignment where the OLT dynamically allocates wavelength channels to ONUs based on network conditions and demand. This dynamic approach allows the existing static power splitter infrastructure to support flexible WDM operations without reconstruction, as wavelength allocation is controlled software-dynamically rather than being hardwired
Solution Approach 2:
The OLT is designed with universal WDM capabilities that allow it to handle multiple wavelength channels and perform multiplexing/demultiplexing functions. This universal OLT design can work with existing power splitter networks, eliminating the need for wavelength-specific infrastructure while maintaining broad network coverage
3Adaptability or versatility
If adjacent receivers with overlapping sensitivity wavebands are used in selectionless ONU scheme, then any wavelength band can be transmitted upstream, but receiver design becomes more complex
Solution Approach 1:
The invention merges the sensitivity wavebands of adjacent receivers so that their coverage areas overlap. This merging approach ensures that any transmitted wavelength falls within the sensitivity range of at least one receiver, providing universal wavelength acceptance while using standard receiver components rather than requiring complex wavelength-selective hardware at each ONU
Data Source
AI summary
A wavelength division multiplexing based passive optical network is disclosed. The network includes an optical line terminal; a power optical splitter connecting to the optical line terminal by an optical fiber; and several optical network units. Each of the optical network units connects to the power optical splitter by each of other optical fibers by a random process.