1.
Vallejo, Luis; Mora, Jose; Jin, Wei; Romero-Huedo, Jaime; Chen, Lin; Tang, Jianming; Ortega, Beatriz
Centralized bidirectional heterogeneous fiber-FSO-mmWave-converged networks for 6G dense cellular network deployments Journal Article
In: Journal of Optical Communications and Networking, vol. 17, no. 12, pp. 1136–1147, 2025, ISSN: 1943-0639, (Publisher: Optica Publishing Group).
Abstract | Links | BibTeX | Tags: Frequency combs, Laser sources, Optical networks, Optical signals, Phase modulation, Signal processing
@article{vallejo_centralized_2025,
title = {Centralized bidirectional heterogeneous fiber-FSO-mmWave-converged networks for 6G dense cellular network deployments},
author = {Luis Vallejo and Jose Mora and Wei Jin and Jaime Romero-Huedo and Lin Chen and Jianming Tang and Beatriz Ortega},
url = {https://opg.optica.org/jocn/abstract.cfm?uri=jocn-17-12-1136},
doi = {10.1364/JOCN.571969},
issn = {1943-0639},
year = {2025},
date = {2025-12-01},
urldate = {2026-02-03},
journal = {Journal of Optical Communications and Networking},
volume = {17},
number = {12},
pages = {1136–1147},
publisher = {Optica Publishing Group},
abstract = {To address the unprecedented technical challenges arising from ultra-dense cellular network deployment for applications in densely populated urban areas envisioned for 6G, this paper proposes and experimentally demonstrates a novel, to our knowledge, centralized bidirectional heterogeneous access network with advanced baseband unit (BBU) pooling and cost-effective remote radio head (RRH) designs free from both lasers and digital signal processing (DSP). The network supports flexible deployments of fiber, free space optical (FSO), and millimeter wave (mmWave) segments, thus ensuring ubiquitous network connectivity. More importantly, it also seamlessly converges various network segments (fiber, FSO, and mmWave) and enables their uplink (UL) and downlink (DL) signals to concurrently and continuously flow between the BBU and user equipment (UE) without requiring optical-electrical/electrical-optical conversions and/or DSPs at any intermediate nodes. In the proposed network, DL mmWave signals are generated and detected using a free-running laser and a passive envelope detection. For the UL case, conventional electrical local oscillators and mixers are used for mmWave up-conversion and down-conversion. The performances of the proposed networks, including UL/DL channel interferences and achievable throughputs, are experimentally evaluated over a fiber-FSO-mmWave setup with 10 km fiber, 1.8 m FSO, and 3 m mmWave links (39 GHz/0.4 Gbit/s for DL, 36.5 GHz/0.2 Gbit/s for UL). The experimental results show robust bidirectional transmissions with negligible UL/DL interferences and minimal impacts from Rayleigh and Brillouin backscattering.},
note = {Publisher: Optica Publishing Group},
keywords = {Frequency combs, Laser sources, Optical networks, Optical signals, Phase modulation, Signal processing},
pubstate = {published},
tppubtype = {article}
}
To address the unprecedented technical challenges arising from ultra-dense cellular network deployment for applications in densely populated urban areas envisioned for 6G, this paper proposes and experimentally demonstrates a novel, to our knowledge, centralized bidirectional heterogeneous access network with advanced baseband unit (BBU) pooling and cost-effective remote radio head (RRH) designs free from both lasers and digital signal processing (DSP). The network supports flexible deployments of fiber, free space optical (FSO), and millimeter wave (mmWave) segments, thus ensuring ubiquitous network connectivity. More importantly, it also seamlessly converges various network segments (fiber, FSO, and mmWave) and enables their uplink (UL) and downlink (DL) signals to concurrently and continuously flow between the BBU and user equipment (UE) without requiring optical-electrical/electrical-optical conversions and/or DSPs at any intermediate nodes. In the proposed network, DL mmWave signals are generated and detected using a free-running laser and a passive envelope detection. For the UL case, conventional electrical local oscillators and mixers are used for mmWave up-conversion and down-conversion. The performances of the proposed networks, including UL/DL channel interferences and achievable throughputs, are experimentally evaluated over a fiber-FSO-mmWave setup with 10 km fiber, 1.8 m FSO, and 3 m mmWave links (39 GHz/0.4 Gbit/s for DL, 36.5 GHz/0.2 Gbit/s for UL). The experimental results show robust bidirectional transmissions with negligible UL/DL interferences and minimal impacts from Rayleigh and Brillouin backscattering.
2.
Vallejo, Luis; Jin, Wei; Tang, Jianming
Seamlessly Converged Optical-Wireless Access Networks Using Free-Running Laser-enabled mmWave Signal Generation and RF Envelope Detection Proceedings Article
In: CLEO 2024 (2024), paper JTu2A.80, pp. JTu2A.80, Optica Publishing Group, 2024.
Abstract | Links | BibTeX | Tags: Bit error rate, Optical access networks, Optical networks, Optical signals, Phase noise, Signal processing
@inproceedings{vallejo_seamlessly_2024,
title = {Seamlessly Converged Optical-Wireless Access Networks Using Free-Running Laser-enabled mmWave Signal Generation and RF Envelope Detection},
author = {Luis Vallejo and Wei Jin and Jianming Tang},
url = {https://opg.optica.org/abstract.cfm?uri=CLEO_AT-2024-JTu2A.80},
doi = {10.1364/CLEO_AT.2024.JTu2A.80},
year = {2024},
date = {2024-05-01},
urldate = {2025-10-08},
booktitle = {CLEO 2024 (2024), paper JTu2A.80},
pages = {JTu2A.80},
publisher = {Optica Publishing Group},
abstract = {Low-cost component-based converged optical-wireless networks without DSP at intermediate RRHs are proposed and experimentally demonstrated, supporting 1.67 Gbit/s/ch dynamic and continuous BBU-UE data flows over 50 km SSMF and 3 m 38 GHz wireless links.},
keywords = {Bit error rate, Optical access networks, Optical networks, Optical signals, Phase noise, Signal processing},
pubstate = {published},
tppubtype = {inproceedings}
}
Low-cost component-based converged optical-wireless networks without DSP at intermediate RRHs are proposed and experimentally demonstrated, supporting 1.67 Gbit/s/ch dynamic and continuous BBU-UE data flows over 50 km SSMF and 3 m 38 GHz wireless links.