Wavelength ID Structure for PON Bandwidth Allocation
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Solution Overview
Problem
Existing passive optical networks (PONs) lack efficient identification of wavelengths and channels for traffic-bearing entities, leading to potential collisions and limited bandwidth allocation in multiple-wavelength PONs.
Innovation Solution
Incorporating an ID structure with a wavelength ID field, ONU-ID field, and traffic-bearing entity ID field in transmission allocations, allowing the Optical Line Terminal (OLT) to manage and assign upstream transmission opportunities, and enabling ONUs to process these IDs for accurate wavelength allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If TDM PON with TDMA scheme is used to share total capacity among multiple users, then device complexity is reduced and ease of operation is improved, but bandwidth per user deteriorates to below 100 Mb/s
Solution Approach 1:
The patent segments the bandwidth allocation by introducing wavelength-level segmentation in addition to time-division multiplexing. Each ONU is assigned dedicated wavelength channels, and within each wavelength, time slots are allocated. This hierarchical segmentation allows simultaneous allocation of multiple wavelength resources to different ONUs, dramatically increasing total bandwidth availability while maintaining the operational simplicity of centralized OLT control.
2Quantity of substance
If WDM PON with dedicated wavelength channel is used for each ONU, then bandwidth per user is improved to up to 10 Gb/s, but device complexity increases due to wavelength management requirements
Solution Approach 1:
The patent implements a universal wavelength allocation framework where the OLT performs multiple functions: wavelength assignment, time slot allocation, and collision management. The standardized ID structure serves multiple purposes by encoding both wavelength identification and time slot information, allowing the same message format to handle both dedicated wavelength assignment and shared wavelength scenarios, thereby reducing overall system complexity.
Solution Approach 2:
The patent changes the parameter representation by encoding wavelength and time slot information into a standardized ID structure with specific bit allocations. This parameter transformation allows the system to manage complex wavelength-time resources using simplified binary encoding, where the OLT can efficiently allocate and track multiple wavelength channels through systematic parameter management rather than complex control logic.
3Productivity
If multiple wavelengths are multiplexed to share a single feeder fiber in TWDM PON, then productivity is improved by serving increased number of users, but reliability deteriorates due to potential wavelength collisions and interference
Solution Approach 1:
The patent applies preliminary action by having the OLT pre-assign specific wavelength channels and time slots to each ONU before data transmission begins. This preliminary allocation is communicated through standardized messages that include wavelength ID and time slot information. By establishing these assignments in advance, the system prevents wavelength collisions and interference before they occur, ensuring reliable simultaneous operation of multiple wavelength channels while maintaining high productivity.
Solution Approach 2:
The patent implements feedback mechanisms where the OLT monitors wavelength channel usage and adjusts allocations dynamically. The standardized ID structure enables the OLT to track which wavelengths are actively used by which ONUs, allowing real-time detection and resolution of potential conflicts. This feedback loop ensures that as more users are added to increase productivity, the system automatically manages wavelength assignments to prevent collisions and maintain reliability.
Data Source
AI summary
An optical line terminal (OLT) comprises a receiver configured to receive a first message, a processor coupled to the receiver and configured to process the first message, and generate a second message based on the first message, wherein the second message comprises an identification (ID) structure identifying a traffic-bearing entity associated with an optical network unit (ONU), and wherein the ID structure comprises a wavelength ID field, and a transmitter coupled to the processor and configured to transmit the second message.