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Improving soft FEC performance for higher-order modulations via optimized bit channel mappings
Optics Express
|July 1, 2014
Summary
Optimizing bit mapping in coded modulation for fiber optics improves performance. This enhancement extends transmission reach by up to 8% for polarization-multiplexed systems using low-density parity-check codes.
Area of Science:
- Optical Communications
- Information Theory
- Coding Theory
Background:
- Bit-interleaved coded modulation (BICM) is a common technique for soft forward error correction with higher-order modulations.
- Polarization-multiplexed fiber-optical systems require efficient error correction strategies, especially without inline dispersion compensation.
- Protograph-based low-density parity-check (LDPC) codes offer hardware efficiency suitable for high-speed optical systems.
Purpose of the Study:
- To optimize the mapping of coded bits to modulation bits in polarization-multiplexed fiber-optical systems.
- To enhance the performance of protograph-based LDPC codes in optical communication systems.
- To evaluate the impact of optimized mapping on transmission reach and system complexity.
Main Methods:
- Optimization of bit mapping for protograph-based LDPC codes, including the AR4JA family and spatially coupled LDPC codes.
- Utilized a windowed decoder for spatially coupled LDPC codes.
- Conducted full-field simulations using the split-step Fourier method for performance verification.
Main Results:
- Achieved performance gains of up to 0.25 dB through optimized bit mapping.
- Demonstrated a potential extension of transmission reach by approximately 8%.
- Confirmed that the performance improvements were obtained without significant increases in system complexity.
Conclusions:
- Optimized bit mapping for protograph-based LDPC codes significantly enhances performance in polarization-multiplexed fiber-optical systems.
- The proposed method offers a practical approach to extend transmission reach in high-speed optical communications.
- The findings support the use of optimized BICM with LDPC codes for future optical network designs.
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