1. Advanced DSP Enabled C-Band 112 Gbit/s/λ PAM-4 Transmissions With Severe Bandwidth-Constraint
- Author
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Yuncai Wang, Di Peng, Meng Xiang, Zhensen Gao, Songnian Fu, Ou Xu, Jianping Li, and Yuwen Qin
- Subjects
Transmission (telecommunications) ,Filter (video) ,Computer science ,Electronic engineering ,Bandwidth (computing) ,Equalization (audio) ,Branch Metrics ,Maximum likelihood sequence estimation ,Interference (wave propagation) ,Precoding ,Atomic and Molecular Physics, and Optics - Abstract
The performance of high-speed intensity modulation direct detection (IM-DD) transmissions is severely degraded by the linear inter-symbol interference (ISI), due to both bandwidth-constrained optoelectrical components and the chromatic dispersion (CD). Meanwhile, nonlinear ISI due to intensity modulation and square-law detection can further deteriorate the IM-DD system performance significantly. Here, we first propose three metrics to quantify those impairments in IM-DD transmissions. Then, we compared both the BER performance and computational complexity of different DSP schemes, using a C-band PAM-4 experimental test-bed with an end-to-end 10-dB bandwidth of 17 GHz. Those DSP schemes include receiver-side feedforward equalization (FFE), receiver-side Volterra filter equalization (VFE), transmitter-side Tomlinson-Harashima precoding (THP) together with receiver-side FFE, transmitter-side THP together with receiver-side VFE, channel-shortening filter (CSF) together with maximum likelihood sequence estimation implemented with linear branch metrics (MLSE-LI-BM), and CSF together with MLSE implemented with nonlinear branch metrics (MLSE-NL-BM). Our experimental results indicate that, only the combination of CSF and MLSE-NL-BM enables a 112 Gbit/s transmission over 5 km fiber at the KP4-FEC threshold, but with an increased computational complexity.
- Published
- 2022