Virtual Lane FEC Interleaving for Multilane OTN Synchronization
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Solution Overview
Problem
In Optical Transport Network (OTN) communications, the correlation between forward error correction (FEC) and virtual lanes is broken in multilane distribution (MLD) protocols, leading to challenges in error rate correlation and equalization parameter adjustment, resulting in increased latency and memory requirements.
Innovation Solution
An interleaving scheme, deinterleaving scheme, decoder feedback loop, and initialization algorithm are used to correlate transceiver parameters with pre-FEC error statistics, ensuring proper synchronization between payload and FEC information, allowing for accurate feedback to individual receivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FEC and payload share the same medium in single-channel systems, then error rate correlation and equalization parameter adjustment are enabled, but this approach cannot be directly applied to multilane distribution systems where FEC and payload are separated across multiple virtual lanes
Solution Approach 1:
The patent implements a feedback mechanism where the receiver monitors pre-FEC error rates for each virtual lane and feeds this information back to the transmitter. The transmitter uses this feedback to adjust equalization parameters and retrain decision feedback equalizers (DFE) for each virtual lane, enabling adaptive error correction in multilane systems without requiring FEC and payload to share the same physical medium.
Solution Approach 2:
The patent segments the error correction process by virtual lane, maintaining separate error rate monitoring and parameter adjustment for each virtual lane rather than treating all lanes uniformly. This segmentation allows the system to handle the complexity of multilane distribution by breaking down the overall error correction task into manageable per-lane operations.
2Productivity
If MLD protocol breaks serial stream into multiple virtual lanes transported over different media, then parallel communication capability is improved, but correlation between channel and FEC information is lost
Solution Approach 1:
The system establishes feedback loops for each virtual lane where the receiver monitors pre-FEC error rates and feeds this information back to the transmitter. This feedback mechanism preserves the correlation between channel conditions and FEC information by providing real-time channel quality metrics that enable adaptive error correction specific to each virtual lane's transmission medium.
Solution Approach 2:
The patent implements preliminary error rate monitoring and parameter adjustment before FEC decoding. By measuring pre-FEC error rates and adjusting equalization parameters in advance, the system prepares the optimal correction parameters for each virtual lane before the actual error correction process, ensuring that FEC information remains correlated with its corresponding channel characteristics.
3Adaptability or versatility
If conventional OTN FEC interleaving schemes are combined with MLD, then multilane transmission is enabled, but decoder FEC performance monitoring parameters cannot be correlated with particular transmission channels
Solution Approach 1:
The patent segments the error rate monitoring process by virtual lane and by FEC block, maintaining separate error counters for each virtual lane's pre-FEC errors. This segmentation ensures that error rate measurements remain precise and correlated with specific transmission channels even when multiple virtual lanes are transmitted over parallel media, as each lane's error statistics are independently tracked and reported.
Data Source
AI summary
A system and method are provided for generating virtual lane (VL) forward error correction (FEC) overhead (OH) in a communication multi-lane distribution (MLD) protocol transmitter, and for recovering data words from virtual lanes with FEC OH in an MLD protocol receiver. The transmission method accepts an Optical Transport Network (OTN) frame with n consecutively ordered payload chunks of data words, at a first data rate. Each payload chunk is assigned to a virtual lane data word (VLDW) in an MLD frame of n consecutively ordered VLDWs. The assignment order of payload chunks to VLDWs is rotated at the start of each MLD frame. VLDWs are joined into VLDW groups, where each VLDW group includes at least one VLDW. FEC blocks are calculated for VLDWs, creating ordered VL codewords (VLCWs). Then, the VLCWs are multiplexed to maintain a consistent assignment of VLCW order to physical transmission lanes and transmitted.