OLT Time Sync Message Threshold Rate Multicast PON
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Solution Overview
Problem
Current standards for passive optical networks (PONs) do not adequately address noise transfer performance between the optical line terminal (OLT) and the optical network unit (ONU), which is crucial for effective time synchronization, particularly due to the asymmetry in upstream and downstream transmission delays and the need for efficient distribution of time of day (ToD) information.
Innovation Solution
The solution involves determining a threshold rate for transmitting time synchronization messages from the OLT to the ONU, with a rate of at least 0.1 messages per second, and employing a multicast or broadcast transmission mechanism to improve efficiency and meet noise transfer performance requirements, allowing for timely and accurate delivery of noise signals and ToD information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If time synchronization messages are transmitted at a low rate to reduce network load, then energy consumption and network traffic are reduced, but time synchronization precision and noise transfer performance deteriorate
Solution Approach 1:
The patent implements periodic transmission of time synchronization messages at a threshold rate of N messages per second (N≥0.1), where N is determined based on the upper cutoff frequency of the noise signal. This periodic action ensures that the noise transfer performance meets the specification fH≥N/2 while maintaining energy efficiency through controlled transmission intervals rather than continuous high-rate transmission
Solution Approach 2:
The patent dynamically adjusts the transmission rate parameter based on the noise signal characteristics. By setting the threshold rate N according to the upper cutoff frequency fH of the noise signal (N≥2×fH), the system optimizes the balance between energy consumption and time synchronization precision, ensuring that the transmission rate adapts to the actual noise transfer requirements
2Measurement precision
If time synchronization messages are transmitted to multiple ONUs individually to ensure accurate noise transfer, then time synchronization precision is improved, but device complexity and transmission overhead increase
Solution Approach 1:
The patent merges the transmission of time synchronization messages to multiple ONUs by utilizing the existing periodic downstream transmission mechanism. The OLT transmits the same time synchronization message at the threshold rate N to all ONUs simultaneously through the optical network, eliminating the need for separate individual transmission management while ensuring that each ONU receives synchronized time information with proper noise transfer characteristics
3Measurement precision
If the transmission rate is increased above the threshold to improve time synchronization accuracy, then time synchronization precision is improved, but network bandwidth consumption and OLT processing load increase
Solution Approach 1:
The patent employs periodic transmission at a precisely calculated threshold rate N (where N≥0.1 and N≥2×fH, with fH being the upper cutoff frequency of the noise signal). This periodic action at the minimum required rate ensures time synchronization accuracy meets the noise transfer specification while avoiding excessive transmission that would burden the OLT processing capacity and consume unnecessary network bandwidth
Data Source
AI summary
Embodiments of the present disclosure relate to methods, optical line terminals (OLTs), optical network units (ONUs), apparatuses and computer storage media for transmitting a time synchronization message. In some example embodiments, the OLT is configured to: determine a threshold rate to be N messages per second for transmission of a time synchronization message to an ONU, wherein N being greater than or equal to 0.1; and transmit, to the ONU, a time synchronization message at the threshold rate or a rate above the threshold rate, to enable the ONU to perform time synchronization with the OLT. In some other example embodiments, the OLT is configured to: select a plurality of ONUs for transmitting time synchronization information; and transmit, to the ONUs, a broadcast or multicast message the time synchronization information, to enable the plurality of ONUs to perform time synchronization with the OLT.