Digital Mobile Fronthaul Based on Performance Enhanced Multi-Stage Noise-Shaping Delta-Sigma Modulator

Ke Bai, Dongdong Zou, Zixuan Zhang, Zibin Li, Wei Wang, Qi Sui, Zizheng Cao, Fan Li (Corresponding author)

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

A novel topology multi-stage noise-shaping (MASH) delta-sigma modulator is proposed for 20-km digital mobile fronthaul (MFH) in this article. In the proposed MASH structure, a newly designed feedback unit is combined with a traditional fourth-order sturdy MASH structure to enhance the noise-shaping capacity. The detailed comparison between the conventional fourth-order single delta-sigma modulator (SDSM) and the proposed new topology MASH is presented in a 512/1024 quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) transmission system with the bandwidth of 1.125 GHz. The OFDM signal is quantized to two bits by SDSM/MASH analog-to-digital conversion (ADC), and this digitized signal is transmitted over 20-km single mode fiber (SMF) in 20-Gbaud 4-level pulse amplitude modulation (PAM4) intensity modulation direct detection (IM/DD) system. The signal to noise ratios (SNRs) of the retrieved OFDM signal utilizing the proposed new topology MASH and the fourth-order SDSM ADCs are 38.7dB and 34.5dB, respectively. In the case of 1024-QAM PAM4 system, the error vector magnitude (EVM) floors of the proposed new topology MASH and the conventional fourth-order SDSM schemes are 1.64% and 1.96% over 20-km SMF transmission at off-line digital signal processing (DSP) reception, and 1.2 dB receiver sensitivity improvement is achieved.

Original languageEnglish
Article number9210181
Pages (from-to)439-447
Number of pages9
JournalJournal of Lightwave Technology
Volume39
Issue number2
DOIs
Publication statusPublished - 15 Jan 2021

Keywords

  • Delta sigma modulation
  • MASH
  • mobile fronthaul
  • quantization noise shaping
  • radio assess network
  • single delta sigma modulation

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