Adaptive Forward Error Correction for Optical Networks
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Solution Overview
Problem
In passive optical networks, different Optical Network Units (ONUs) have varying performance requirements and tolerance levels, making it challenging to achieve optimal throughput and error correction due to differing data rates and modulation formats, especially when using frame bursting schemes.
Innovation Solution
The proposed solution involves adjusting the Forward Error Correction (FEC) overhead length by employing shortening and puncturing techniques to match the performance capability of each ONU, allowing for dynamic adjustment of the FEC code size and payload size ratio, which can be centrally or distributively controlled.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed FEC code size is used for all ONUs, then system complexity is reduced, but throughput optimization for different ONUs cannot be achieved
Solution Approach 1:
The patent implements dynamic FEC configuration by allowing the OLT to adjust the FEC code size (k value) adaptively for each ONU based on its performance capability. The system transitions from a static, one-size-fits-all FEC approach to a dynamic, ONU-specific configuration where the FEC parameters are adjusted in real-time to match each ONU's throughput requirements and error correction needs.
Solution Approach 2:
The patent changes the FEC system parameters (specifically the code size k and overhead length) to optimize performance for different ONUs. By varying the FEC code size parameter based on ONU performance capability information, the system achieves throughput optimization without requiring a complete redesign of the FEC structure.
2Reliability
If FEC overhead length is increased to improve error correction, then bit error rate performance improves, but data throughput decreases
Solution Approach 1:
The patent applies local quality by tailoring the FEC overhead length specifically to each ONU's performance capability and distance from the OLT. Instead of using a uniform FEC configuration across all ONUs, the system adjusts the overhead length locally for each ONU, providing stronger error correction only where needed (for ONUs with poorer performance or greater distance) while maintaining higher throughput for ONUs with better performance.
Solution Approach 2:
The system dynamically adjusts the FEC overhead length based on real-time or near-real-time performance capability information from each ONU. This dynamic adjustment allows the system to optimize the balance between error correction and throughput for each individual ONU rather than using a fixed, conservative configuration that would limit throughput for all ONUs.
3Productivity
If frame bursting scheme is used to increase throughput, then data transmission efficiency improves, but performance variation among different ONUs increases
Solution Approach 1:
The patent addresses performance variation among ONUs by applying local quality through ONU-specific FEC configurations. Each ONU receives a customized FEC code size and overhead length based on its individual performance capability, allowing the frame bursting scheme to operate efficiently for each ONU without being constrained by the limitations of other ONUs in the network.
Data Source
AI summary
A method of communication using a forward error correction (FEC) code includes receiving, at an optical line terminal (OLT), performance capability information provided by an optical network unit (ONU), adjusting, at the OLT, a ratio between an FEC code size and a payload size based on the performance capability information, and informing the ONU of the FEC code size selected based on the ratio such that message exchanges between the ONU and the OLT are performed using the FEC code size to which the ratio is applied.