Open AccessImproving performance of mobile fronthaul architecture employing high order delta-sigma modulator with PAM-4 format
Author(s) -
Haibo Li,
Rong Hu,
Qi Yang,
Ming Luo,
Zhixue He,
Peng Jiang,
Yongpiao Liu,
Xiang Li,
Shaohua Yu
Publication year - 2017
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.25.000001
Subject(s) - delta sigma modulation , electronic engineering , quantization (signal processing) , modulation (music) , computer science , delta modulation , transmission (telecommunications) , bit error rate , noise shaping , sigma , channel (broadcasting) , physics , bandwidth (computing) , telecommunications , engineering , pulse amplitude modulation , algorithm , detector , acoustics , pulse (music) , quantum mechanics
An improved high-order delta-sigma modulator with multi-level quantizer is proposed to enable carrier aggregation of 4G-LTE signals in mobile fronthaul. Different from conventional delta-sigma modulation-based digital mobile fronthaul, a 2-bit quantizer is employed to reduce the quantization noise, which enabling the transmission via PAM-4 based IM-DD channel. Moreover, we employ the 4th-order high-pass filter (HPF) to replace the 1st-order HPF in the conventional delta-sigma modulator, resulting in a much better noise shaping performance. In the experiment, a PAM-4 based mobile fronthaul transmission of 32 aggregated 4G-LTE signals with a CPRI equivalent data rate of 39.32-Gb/s is demonstrated in a single-λ 10-Gb/s IM-DD channel. Significant improvement of 68% is achieved in the average EVM performance compared to the previous delta-sigma modulation-based digital mobile fronthaul.