Passive Optical Network Multi-OLT Access via AWG Filter
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Solution Overview
Problem
Current passive optical network (PON) designs do not allow access to optical node units from different optical line terminals, limiting open access capabilities and requiring network providers to access the central office, which is a barrier to market requirements and regulatory demands for open access.
Innovation Solution
A PON structure with at least two optical line terminals (OLTs) coupled to a remote node (RN) having M WDM ports and N distribution ports, utilizing a passive optical filter device with spectral and spatial filter properties of an M x N arrayed waveguide grating, allowing each OLT to communicate unidirectionally or bidirectionally with ONUs using different wavelengths, and a common control device to manage communication links between OLTs and ONUs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single OLT is used in the PON structure, then the network design is simple and easy to manage, but open access capabilities are limited and multiple providers cannot access ONUs
Solution Approach 1:
The remote node is designed with M WDM ports that can accommodate multiple OLTs, allowing the same network infrastructure to serve multiple service providers. The passive optical filter device with M x N arrayed waveguide grating structure enables universal access where any OLT can communicate with any ONU through appropriate wavelength routing,实现ing multi-provider open access without requiring separate network infrastructures for each provider
Solution Approach 2:
The patent introduces wavelength as an additional dimension for signal routing. By assigning different wavelengths to different OLTs and using the spectral filter properties of the arrayed waveguide grating, the system enables multiple OLTs to share the same physical infrastructure without interference. This wavelength dimension allows multiple providers to access the network simultaneously through the same remote node and distribution fibers
2Adaptability or versatility
If multiple OLTs are coupled to the RN with different wavelengths, then open access capabilities are enabled, but the device complexity and wavelength management become more challenging
Solution Approach 1:
The passive optical filter device acts as an intermediary between multiple OLTs and ONUs. It automatically routes signals from any OLT to any ONU based on wavelength matching without requiring active control or complex switching logic. The filter device mediates the wavelength management by its inherent spectral selectivity, simplifying the overall system control while enabling multi-OLT access
Solution Approach 2:
The arrayed waveguide grating structure provides self-service wavelength routing through its cyclic spectral and spatial filter properties. The device automatically directs signals based on their wavelength characteristics without external intervention, with the M WDM ports and N distribution ports naturally establishing transparent optical transmission paths based on the optical signals' wavelengths alone
3Adaptability or versatility
If a passive optical filter device with M x N arrayed waveguide grating is used, then transparent optical transmission paths are defined for multiple OLTs and ONUs, but the manufacturing precision and cost increase
Solution Approach 1:
The patent uses the cyclic properties of the arrayed waveguide grating to create more wavelength paths than strictly necessary for basic functionality. By utilizing the full M x N port configuration with cyclic spectral filtering, the system achieves robust multi-provider access and flexibility. This excessive capability provides built-in redundancy and adaptability, allowing any OLT to access any ONU through multiple possible wavelength paths, thereby enhancing open access capabilities while the cyclic structure maintains manufacturing feasibility
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables access to ONUs from different OLTs, facilitating open access PONs by allowing multiple communication links between OLTs and ONUs, with the ability to select which provider has access to a selected ONU, and simplifying the design and implementation of the network.
Implementation Method 1
a passive optical filter device with spectral and spatial filter properties of an M x N arrayed waveguide grating
Implementation Method 2
M x N arrayed waveguide grating
Implementation Method 3
a passive optical filter device with spectral and spatial filter properties of an M x N arrayed waveguide grating
Data Source
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AI summary
The invention relates to a passive optical network comprising at least two optical line terminals (3, 103, 303, 403), a remote node (7) and a plurality of optical node units (5, 105, 205, 405), each optical line terminal (3, 103, 303, 403) having a WDM working port (9i), the remote node (7) having a predetermined number of M WDM ports (13j) and a predetermined number of N distribution ports (15k), and each optical node unit (5, 105, 205, 405) having a communication port (21k), each optical line terminal WDM working port (13j) being connected to a dedicated remote node WDM port (13j) by a respective working feeder fiber (17), and each optical node unit communication port (21k) being connected to a dedicated remote node distribution port (15k) by a respective distribution fiber (23), the remote node (7) comprising a passive optical filter device 25) adapted to realize a spectral and spatial filter property of an M x N arrayed waveguide grating, the passive optical filter device (25) defining the M WDM ports (13j) and the N distribution ports (15k), and each optical line terminal (3, 103, 303, 403) being operable to unidirectionally or bidirectionally communicate with one or more selected or all optical node units (5, 105, 205, 405) using optical channel working signals, wherein each optical line terminal (3, 103, 303, 403) is operable to create and to supply to the working fiber (17) respective downstream optical working channel signals, each of the downstream optical channel working signals being created at a downstream working wavelength suitable for establishing, at the respective downstream working wavelength, a communication link between the optical line terminal (3, 103, 303, 403) and the respective optical node unit (5, 105, 205, 405) via an optical working transmission path comprising the working feeder fiber (17), the remote node (7) and the respective distribution fiber (23). Further, the invention relates to an optical line terminal (3, 103, 303, 403) for realizing such a passive optical network according (1, 100, 200, 300, 400).