WDM-TDM PON Wavelength Assignment Based on Effective Transmission Rates
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Solution Overview
Problem
In WDM/TDM-PON systems, communication bandwidths among wavelengths become unfair due to differences in effective transmission rates among ONUs, leading to inefficient bandwidth allocation.
Innovation Solution
A network system where the station-side apparatus determines wavelengths for each ONU based on their effective transmission rates, using wavelength-tunable optical transceivers and controllers to ensure fair bandwidth distribution by adjusting FEC code rates and transmission rates dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FEC is applied to all ONUs regardless of distance, then transmission reliability is improved for long-distant ONUs, but transmission efficiency is degraded for short-distant ONUs due to unnecessary FEC redundant codes
Solution Approach 1:
The patent applies different FEC configurations to different ONUs based on their specific conditions. The OLT determines whether to apply FEC to each ONU individually by comparing transmission loss against a threshold value, allowing short-distant ONUs to transmit without FEC while long-distant ONUs use FEC for reliable transmission.
Solution Approach 2:
The patent dynamically changes the FEC application parameter based on transmission loss conditions. The OLT adjusts the FEC configuration parameter for each ONU according to measured transmission loss, switching between FEC-on and FEC-off states to optimize the balance between reliability and efficiency.
2Ease of operation
If wavelengths are assigned based on the number of registered ONUs, then wavelength assignment is simplified, but communication bandwidth fairness among wavelengths is degraded
Solution Approach 1:
The patent implements a feedback mechanism where the OLT measures the effective transmission rate for each ONU and uses this information to adjust wavelength assignments. The OLT determines appropriate wavelengths by considering the actual transmission performance rather than just the number of ONUs, ensuring fair bandwidth distribution across all wavelengths.
Solution Approach 2:
The patent makes the wavelength assignment dynamic rather than static. The OLT continuously monitors transmission loss and effective transmission rates, and adjusts wavelength assignments in real-time based on changing conditions, allowing the system to adapt to varying ONU requirements and maintain bandwidth fairness.
3Adaptability or versatility
If DBA control dynamically determines transmission periods based on required bandwidth, then bandwidth allocation flexibility is improved, but control complexity increases
Solution Approach 1:
The patent performs preliminary determination of transmission loss and effective transmission rate before executing DBA control. By pre-calculating these parameters and storing them in the OLT, the system reduces the computational complexity during real-time DBA operations, as the OLT only needs to compare pre-computed values rather than calculate everything from scratch.
Data Source
AI summary
An aspect of this invention is a network system including subscriber apparatuses and a station-side apparatus for communicating with the subscriber apparatuses. The station-side apparatus communicates with the subscriber apparatuses using wavelengths. The station-side apparatus determines a wavelength to be used by each of at least one subscriber apparatus of the subscriber apparatuses based on effective transmission rates used by the subscriber apparatuses in communications with the station-side apparatus.