Dynamic FEC Code Length Selection for PON Efficiency
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Solution Overview
Problem
Current passive optical networks (PON) face inefficiencies due to the limited options for Forward Error Correction (FEC) codes, which result in high overhead and reduced link capacity, as they only allow for either FEC on or off, with RS(248,216 being the standard, leading to unnecessary bandwidth wastage and suboptimal error correction.
Innovation Solution
Implementing multiple FEC code lengths such as RS(248,240), RS(248,232), and RS(248,224, which reduce FEC overhead, and dynamically switching between them based on performance monitoring counters to optimize link efficiency, allowing the Optical Line Terminal (OLT) to select the appropriate FEC code length for each Optical Network Unit (ONU) to match the required coding gain and error correction needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single FEC code length (RS(248,216)) is used in PON, then error correction capability is provided, but FEC overhead is high (13%) and link capacity is reduced
Solution Approach 1:
The patent implements dynamic FEC code length selection where the OLT can choose from multiple FEC code lengths (RS(248,240), RS(248,232), RS(248,224), RS(248,216)) based on real-time performance monitoring counters. This allows the system to adapt the FEC overhead to the actual link conditions, using stronger correction only when necessary and weaker correction when the link is good, thereby maximizing link capacity while maintaining reliability.
Solution Approach 2:
The patent changes the FEC code length parameter dynamically based on performance monitoring. By monitoring error rates and link quality metrics, the system adjusts the FEC code length parameter to optimize the balance between error correction capability and link capacity utilization.
2Reliability
If FEC is activated with standard RS(248,216), then error correction is provided, but bandwidth utilization is suboptimal due to fixed overhead
Solution Approach 1:
The system dynamically adjusts FEC code length based on monitored performance counters, transitioning from static to dynamic operation. This allows bandwidth utilization to be optimized in real-time according to actual link conditions, improving productivity while maintaining the necessary error correction capability.
Solution Approach 2:
By changing the FEC code length parameter based on performance monitoring, the system optimizes bandwidth utilization. When link conditions are good, shorter FEC codes are used to maximize bandwidth; when conditions deteriorate, longer FEC codes provide stronger protection, thus optimizing the productively-bandwidth tradeoff.
3Productivity
If multiple FEC code lengths are implemented, then link capacity and efficiency are optimized, but device complexity increases
Solution Approach 1:
The system implements self-service through automatic FEC code length selection based on performance monitoring counters. The OLT autonomously monitors link performance and selects the appropriate FEC code length without requiring manual configuration or complex external control, thereby optimizing link efficiency while managing device complexity through automation.
Solution Approach 2:
The patent uses performance monitoring counters as feedback to automatically adjust FEC code length. This feedback mechanism allows the system to self-optimize link efficiency based on actual performance data, reducing the need for complex manual configuration while maintaining high productivity.
4Reliability
If a longer FEC code length is used for broadcast messages, then error protection is improved, but overhead increases compared to unicast messages
Solution Approach 1:
The patent applies different FEC code lengths to different message types and link conditions. Broadcast messages may use longer FEC codes when link quality is poor, while unicast messages use shorter codes when conditions are good. This local quality approach optimizes error protection for each communication type based on its specific requirements and current link conditions, minimizing overall overhead.
Data Source
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AI summary
Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for optimizing PON efficiency using a variable FEC. In one aspect, an OLT broadcasts a message over an optical network, and receives, from an ONU, a response to the message. The OLT transmits activation parameters specifying that the OLT supports multiple different FEC code lengths when FEC is activated, and receives from the ONU, a set of FEC code lengths supported by the ONU. The OLT also receives performance measures collected by the ONU. The OLT selects, from among the FEC code lengths supported by the ONU, one or more appropriate FEC code lengths for communications between the ONU and the OLT based on the performance measures collected by the ONU and performance measures collected by the OLT. The OLT configures the ONU to utilize the appropriate FEC code length.