Soft-Decision Optical Receiver With Low-Rate Quantized LLR Links
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Solution Overview
Problem
High-speed passive optical networks face challenges in implementing soft decision decoding due to impractical and costly 300 Gb/s connections between optical and digital signal processing devices, which are necessary for effective forward error correction, especially at data rates of 50 Gbit/s per wavelength.
Innovation Solution
A low-complexity soft decision optical receiver architecture that uses limited data rate connections by reducing the resolution of exchanged amplitude information to a few bits (e.g., 2 bits per symbol) between an ODSP device and a TCL device, optimizing quantization thresholds based on signal statistics, and performing soft decision decoding with lower power consumption and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-speed electrical connections (300 Gb/s) are used between ODSP and TCL devices to enable soft decision decoding, then forward error correction performance is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent changes the parameter of data rate from 300 Gb/s to lower rates (e.g., 100 Gb/s or less) by reducing the resolution of amplitude information exchange. Instead of transmitting full-precision soft decision values, the system quantizes them to fewer bits, thereby lowering the required connection speed and complexity while preserving sufficient error correction performance.
Solution Approach 2:
The patent uses simplified quantization thresholds and reduced-resolution amplitude information that can be computed and transmitted with lower complexity. These simplified data structures replace the need for high-speed, high-precision connections, effectively using cheaper transmission resources to achieve the same functional goal.
2Reliability
If high-speed electrical connections (300 Gb/s) are used between ODSP and TCL devices, then soft decision decoding capability is improved, but power consumption increases
Solution Approach 1:
The patent reduces the data rate parameter from 300 Gb/s to lower values by quantizing amplitude information to fewer bits. This parameter change directly reduces the power consumption of the electrical connection while maintaining the essential soft decision decoding capability needed for effective forward error correction.
3Reliability
If quantization thresholds are optimized based on signal statistics, then forward error correction performance is improved, but processing complexity increases
Solution Approach 1:
The patent performs quantization threshold optimization in advance using measured signal statistics (mean and variance). The optimized thresholds are stored and reused for subsequent decoding operations, avoiding the need for real-time complex calculations during actual data transmission and decoding, thus reducing processing complexity while maintaining performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the performance of forward error correction decoders with lower complexity and cost, supporting data rates of 100 Gb/s while maintaining effective signal processing, even at distances where high-speed connections are impractical.
Implementation Method 1
an optical and digital signal processing (ODSP) device. The ODSP device may include a photodiode that may convert an optical signal to an electrical signal
Data Source
AI summary
Technology is disclosed for an optical receiver. The optical receiver may include an optical and digital signal processing (ODSP) device. The ODSP device may include a photodiode operable to convert an optical signal to an electrical signal; a digital signal processor operable to generate a digital signal based on the electrical signal; a quantization component operable to generate a quantized output signal based on the digital signal; and a processing device. The processing device may be operable to measure one or more signal statistics of the digital signal; and identify one or more quantization thresholds, wherein the one or more quantization thresholds are computed based on the one or more signal statistics.