Comparison of Bit-Loading DMT and Pre-Equalized DFT-Spread DMT for 2-km Optical Interconnect System

• Published in: Journal of lightwave technology Vol. 37; no. 10; pp. 2194 - 2200
• Main Authors: Zou, Dongdong, Chen, Yongchao, Li, Fan, Li, Zibin, Sun, Yidan, Ding, Li, Li, Jianping, Yi, Xingwen, Li, Liangchuan, Li, Zhaohui
• Format: Journal Article
• Language: English
• Published: New York IEEE 15.05.2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Bandwidth; Bit error rate; Bit-loading; Broadband; Channel estimation; Communications systems; Curve fitting; discrete multi-tone (DMT); discrete-fourier-transform spread (DFT-Spread); Equalization; Error correction; Fading; Fading channels; Fitting; Fourier transforms; High frequency; intensity modulation with direct detection (IM/DD); Modulation; Optical interconnects; Optical wireless; pre-equalization; Signal to noise ratio; Wideband communications
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2019.2899737

In this paper, we experimentally compared the performance of bit-loading discrete multi-tone (DMT) and pre-equalized discrete-Fourier-transform spread (DFT-Spread) DMT in intensity modulation with direct detection (IM/DD) system for 2-km optical interconnect for the first time. Pre-equalization is applied to compensate the high-frequency power fading in wideband communication system. However, it remains to be verified whether zero-forcing (ZF) channel estimation based complete pre-equalization can achieve the best performance for system with serious high frequency fading. In an IM/DD system with 120 Gbit/s data rate, we demonstrated that the bit error rate of DFT-Spread DMT signal with optimized quadratic curve fitting based partial pre-equalization outperforms ZF based complete pre-equalization after 2-km standard single mode fiber (SSMF) transmission. What's more, we experimentally compared the performance of pre-equalized DFT-Spread DMT and Chow-Cioffi-Bingham (CCB) algorithm-based bit loading DMT. The results show that the receiver sensitivity of pre-equalized DFT-Spread DMT is improved by 2.5 dB compared with CCB algorithm-based bit-loading DMT at hard decision forward error correction threshold of 3.8 × 10 -3 after 2-km SSMF transmission.