Optical Bus Splitter Topology for Peer-to-Peer ONU Resilience
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Solution Overview
Problem
Existing passive optical network (PON) systems lack peer-to-peer optical signal channels between ONUs, leading to communication disruptions when feeder fibers disconnect or OLTs fail, particularly in industrial scenarios like mines, where reliability and redundancy are critical.
Innovation Solution
Implement an optical bus structure with peer-to-peer topologies using a splitting apparatus comprising M groups of ports and M splitting elements, where each branch end of each element is interconnected, allowing peer-to-peer optical channels between any two groups of ports, and incorporate dual-mode ONUs that can switch between ONU and OLT modes to ensure continuous communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional PON system with a single OLT and splitter is used, then the system structure is simple, but the network reliability deteriorates when feeder fibers disconnect or OLTs fail
Solution Approach 1:
The system is segmented into multiple independent OLTs instead of relying on a single OLT. Each OLT connects to the splitter through separate feeder fibers, creating independent transmission paths. This segmentation ensures that a failure in one OLT or its feeder fiber does not affect the entire network, thereby improving reliability while maintaining manageable system complexity through modular architecture
Solution Approach 2:
The system implements beforehand cushioning by preparing redundant OLTs and feeder fiber paths in advance. When the primary OLT or feeder fiber fails, the standby OLT is already positioned to take over, providing immediate backup without requiring complex real-time reconfiguration. This proactive approach enhances network reliability while keeping the system structure relatively simple through pre-configured redundancy
2Reliability
If peer-to-peer optical channels between ONUs are implemented, then communication reliability improves, but the device complexity increases due to additional splitting elements and interconnections
Solution Approach 1:
Multiple splitting elements are merged into a unified splitting apparatus structure where M splitting elements (each with 1 feeder end and N branch ends) are interconnected through their branch ends. This merging creates peer-to-peer optical channels between different ONU groups while sharing common infrastructure, thereby improving communication reliability without proportionally increasing overall system complexity
Solution Approach 2:
The splitting apparatus is designed with multi-functionality to serve dual purposes: it maintains the traditional star topology for OLT-to-ONU communication while simultaneously enabling peer-to-peer optical channels between ONUs. The same M splitting elements and their interconnections support both communication modes, avoiding the need for separate dedicated infrastructure and thus limiting the increase in device complexity
3Reliability
If dual-mode ONUs with switching capability are deployed, then network redundancy and reliability improve, but the device complexity and cost of individual ONUs increase
Solution Approach 1:
The ONU is designed with dynamic switching capability that allows it to adapt its operating mode based on network conditions. The dual-mode ONU can dynamically switch between traditional ONU mode (receiving signals from OLT) and OLT mode (acting as a substitute OLT when primary OLT fails). This dynamic adaptability provides network redundancy and improves reliability while keeping the ONU structure relatively compact by sharing common hardware resources across both modes
Data Source
AI summary
A splitting apparatus provides M groups of ports and includes M splitting elements. Each splitting element includes at least one feeder end and N branch ends, where M=N+1. Each branch end of each splitting element is coupled to one branch end of another splitting element in the M splitting elements, where different branch ends of each splitting element are coupled to one branch end of different splitting elements. A feeder end of each splitting element is coupled to one group of ports in the M groups of ports of the splitting apparatus, and feeder ends of different splitting elements are coupled to different groups of ports. The splitting apparatus may implement an optical bus structure with peer-to-peer topologies.