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A bit-interleaved sigma-delta-over-fiber fronthaul network for frequency-synchronous distributed antenna systems

Chia-Yi Wu (UGent) , Haolin Li (UGent) , Joris Van Kerrebrouck (UGent) , Caro Meysmans (UGent) , Piet Demeester (UGent) and Guy Torfs (UGent)
Author
Organization
Project
  • ATTO (A new concept for ultra-high capacity wireless networks.)
  • BI-SDMoF (Bit-interleaved sigma-delta modulation over fiber)
Abstract
Cell-free massive multiple-input multiple-output (MIMO) has attracted wide attention as wireless spectral efficiency has become a 6G key performance indicator. The distributed scheme improves the spectral efficiency and user fairness, but the fronthaul network must evolve to enable it. This work demonstrates a fronthaul network for distributed antenna systems enabled by the bit-interleaved sigma-delta-over-fiber (BISDoF) concept: multiple sigma-delta modulated baseband signals are time-interleaved into one non-return-to-zero (NRZ) signal, which is converted to the optical domain by a commercial QSFP and transmitted over fiber. The BISDoF concept improves the optical bit-rate efficiency while keeping the remote unit complexity sufficiently low. The implementation successfully deals with an essential challenge-precise frequency synchronization of different remote units. Moreover, owing to the straightforward data paths, all transceivers inherently transmit or receive with fixed timing offsets which can be easily calibrated. The error vector magnitudes of both the downlink and uplink data paths are less than 2.8% (-31 dB) when transmitting 40.96 MHz-bandwidth OFDM signals (256-QAM) centered around 3.6 GHz. (Optical path: 100 m multi-mode fibers; wireless path: electrical back-to-back.) Without providing an extra reference clock, the two remote units were observed to have the same carrier frequency; the standard deviation of the relative jitter was 9.43 ps.
Keywords
MASSIVE MIMO, 5G and beyond, 6G, cell-free massive MIMO, distributed antenna system, (DAS), fronthaul network, next-generation radio access network (NG-RAN), radio-over-fiber (RoF), sigma-delta modulation (SDM)

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Citation

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MLA
Wu, Chia-Yi, et al. “A Bit-Interleaved Sigma-Delta-over-Fiber Fronthaul Network for Frequency-Synchronous Distributed Antenna Systems.” APPLIED SCIENCES-BASEL, vol. 11, no. 23, 2021, doi:10.3390/app112311471.
APA
Wu, C.-Y., Li, H., Van Kerrebrouck, J., Meysmans, C., Demeester, P., & Torfs, G. (2021). A bit-interleaved sigma-delta-over-fiber fronthaul network for frequency-synchronous distributed antenna systems. APPLIED SCIENCES-BASEL, 11(23). https://doi.org/10.3390/app112311471
Chicago author-date
Wu, Chia-Yi, Haolin Li, Joris Van Kerrebrouck, Caro Meysmans, Piet Demeester, and Guy Torfs. 2021. “A Bit-Interleaved Sigma-Delta-over-Fiber Fronthaul Network for Frequency-Synchronous Distributed Antenna Systems.” APPLIED SCIENCES-BASEL 11 (23). https://doi.org/10.3390/app112311471.
Chicago author-date (all authors)
Wu, Chia-Yi, Haolin Li, Joris Van Kerrebrouck, Caro Meysmans, Piet Demeester, and Guy Torfs. 2021. “A Bit-Interleaved Sigma-Delta-over-Fiber Fronthaul Network for Frequency-Synchronous Distributed Antenna Systems.” APPLIED SCIENCES-BASEL 11 (23). doi:10.3390/app112311471.
Vancouver
1.
Wu C-Y, Li H, Van Kerrebrouck J, Meysmans C, Demeester P, Torfs G. A bit-interleaved sigma-delta-over-fiber fronthaul network for frequency-synchronous distributed antenna systems. APPLIED SCIENCES-BASEL. 2021;11(23).
IEEE
[1]
C.-Y. Wu, H. Li, J. Van Kerrebrouck, C. Meysmans, P. Demeester, and G. Torfs, “A bit-interleaved sigma-delta-over-fiber fronthaul network for frequency-synchronous distributed antenna systems,” APPLIED SCIENCES-BASEL, vol. 11, no. 23, 2021.
@article{8736950,
  abstract     = {{Cell-free massive multiple-input multiple-output (MIMO) has attracted wide attention as wireless spectral efficiency has become a 6G key performance indicator. The distributed scheme improves the spectral efficiency and user fairness, but the fronthaul network must evolve to enable it. This work demonstrates a fronthaul network for distributed antenna systems enabled by the bit-interleaved sigma-delta-over-fiber (BISDoF) concept: multiple sigma-delta modulated baseband signals are time-interleaved into one non-return-to-zero (NRZ) signal, which is converted to the optical domain by a commercial QSFP and transmitted over fiber. The BISDoF concept improves the optical bit-rate efficiency while keeping the remote unit complexity sufficiently low. The implementation successfully deals with an essential challenge-precise frequency synchronization of different remote units. Moreover, owing to the straightforward data paths, all transceivers inherently transmit or receive with fixed timing offsets which can be easily calibrated. The error vector magnitudes of both the downlink and uplink data paths are less than 2.8% (-31 dB) when transmitting 40.96 MHz-bandwidth OFDM signals (256-QAM) centered around 3.6 GHz. (Optical path: 100 m multi-mode fibers; wireless path: electrical back-to-back.) Without providing an extra reference clock, the two remote units were observed to have the same carrier frequency; the standard deviation of the relative jitter was 9.43 ps.}},
  articleno    = {{11471}},
  author       = {{Wu, Chia-Yi and Li, Haolin and Van Kerrebrouck, Joris and Meysmans, Caro and Demeester, Piet and Torfs, Guy}},
  issn         = {{2076-3417}},
  journal      = {{APPLIED SCIENCES-BASEL}},
  keywords     = {{MASSIVE MIMO,5G and beyond,6G,cell-free massive MIMO,distributed antenna system,(DAS),fronthaul network,next-generation radio access network (NG-RAN),radio-over-fiber (RoF),sigma-delta modulation (SDM)}},
  language     = {{eng}},
  number       = {{23}},
  pages        = {{14}},
  title        = {{A bit-interleaved sigma-delta-over-fiber fronthaul network for frequency-synchronous distributed antenna systems}},
  url          = {{http://dx.doi.org/10.3390/app112311471}},
  volume       = {{11}},
  year         = {{2021}},
}

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