Papers

Research on a remote true-time-delay multi-beamforming system based on multicore fibers

  • Chenbo ZHANG , 1 ,
  • Yixiao ZHU , 2, * ,
  • Weisheng HU 2
Expand
  • 1. School of Electronics, Peking University, Beijing 100871, China
  • 2. Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

Received date: 2025-05-06

  Revised date: 2025-05-22

  Online published: 2025-07-03

Copyright

All rights reserved. Unauthorized reproduction is prohibited.

Abstract

In 5G/6G radio-over-fiber (RoF) networks, remote radio units (RUs) require multi-beamforming functionality to ensure reliable access for ubiquitous mobile terminals. To meet this requirement, multi-core fibers (MCFs) have emerged as a promising solution for RoF links due to their advantages of supporting multiple channels and maintaining excellent inter-channel delay consistency. Here, we proposes a remote optical true-time-delay multi-beamforming architecture based on MCFs, which is suitable for 5G RoF networks. The architecture utilizes MCFs as the link, while deploying chirped fiber Bragg gratings with equal dispersion spacing to provide equal-space time delays at the centralized unit. By independently tuning the wavelengths of each optical carriers, the corresponding beam direction can be continuously adjusted, enabling centralized multi-beam control. To validate the feasibility of this architecture, we use a 2-km 7-core fiber as the RoF link for experiment and build a 2×2 remote beamforming system. Experimental results demonstrate that by tuning the wavelength of each optical carrier, independent control of each beam direction can be achieved. Compared to single-mode fibers, MCF reduces inter-channel delay jitter by more than an order of magnitude, with a maximum delay jitter of 1.7 ps, ensuring long-term stability of the beam direction. Furthermore, the inter-core crosstalk of MCF has a negligible impact on both the preset delays and the signal-to-noise ratio of broadband wireless signals. This architecture provides a feasible and stable solution for realizing remote beamforming, offering significant application value for 5G/6G mobile access networks.

Cite this article

Chenbo ZHANG , Yixiao ZHU , Weisheng HU . Research on a remote true-time-delay multi-beamforming system based on multicore fibers[J]. Science & Technology Review, 2025 , 43(12) : 153 -160 . DOI: 10.3981/j.issn.1000-7857.2025.05.00016

1
Osseiran A , Monserrat J F , Marsch P . 5G移动无线通信技术[M]. 北京: 人民邮电出版社, 2017.

2
Lim C , Nirmalathas A . Radio-over-fiber technology: Present and future[J]. Journal of Lightwave Technology, 2021, 39 (4): 881- 888.

DOI

3
邬贺铨. 5G开启移动通信新时代[J]. 科技导报, 2020, 38 (2): 1.

4
刘海鹏, 周淑秋. 5G行业专网应用研究进展[J]. 科技导报, 2022, 40 (23): 97- 105.

DOI

5
Pan S L , Zhang Y M . Microwave photonic radars[J]. Journal of Lightwave Technology, 2020, 38 (19): 5450- 5484.

DOI

6
Ye X W , Zhang F Z , Pan S L . Optical true time delay unit for multi-beamforming[J]. Optics Express, 2015, 23 (8): 10002- 10008.

DOI

7
夏明耀, 王均宏. 电磁场理论与计算方法要论[M]. 北京: 北京大学出版社, 2013.

8
Corral J L , Marti J , Regidor S , et al. Continuously variable true time-delay optical feeder for phased-array antenna employing chirped fiber grating[J]. IEEE Transactions on Microwave Theory and Techniques, 1997, 45 (8): 1531- 1536.

DOI

9
Shi N N , Li W , Zhu N H , et al. Optically controlled phase array antenna[J]. Chinese Optics Letters, 2019, 17 (5): 052301.

DOI

10
Kim M , Hacker J B , Mihailovich R E , et al. A DC-to-40 GHz four-bit RF MEMS true-time delay network[J]. IEEE Microwave and Wireless Components Letters, 2001, 11 (2): 56- 58.

DOI

11
Zhu C , Lu L J , Shan W S , et al. Silicon integrated microwave photonic beamformer[J]. Optica, 2020, 7 (9): 1162.

DOI

12
Cheng Q M , Zheng S L , Zhang Q , et al. An integrated optical beamforming network for two-dimensional phased array radar[J]. Optics Communications, 2021, 489: 126809.

DOI

13
Xue X X , Xuan Y , Bao C Y , et al. Microcomb-based true-time-delay network for microwave beamforming with arbitrary beam pattern control[J]. Journal of Lightwave Technology, 2018, 36 (12): 2312- 2321.

DOI

14
Pastor D , Ortega B , Capmany J , et al. Fully automatic simultaneous fiber grating amplitude and group delay characterization[J]. Microwave and Optical Technology Letters, 1997, 14 (6): 373- 375.

DOI

15
Morant M , Trinidad A , Tangdiongga E , et al. Multi-beamforming provided by dual-wavelength true time delay PIC and multicore fiber[J]. Journal of Lightwave Technology, 2020, 38 (19): 5311- 5317.

DOI

16
Zhang C B , Gao Y Y , Zuo M Q , et al. Using ASE sources in remote beamforming system with Space-Division-Multiplex fiber[J]. Optics Communications, 2022, 504: 127477.

DOI

17
Zhang C B , Lei P , Liu R W , et al. Large-scale true-time- delay remote beamforming with EO frequency combs and multicore fiber[J]. Optics Letters, 2021, 46 (15): 3793- 3796.

DOI

Outlines

/