@article{he_experimental_2025,

title = {Experimental Demonstrations of Chaotic Digital Filter-Based Physical Layer Security in Converged Fibre-mmWave Access Networks},

author = {Jiaxiang He and Luis Vallejo and Roger Philip Giddings and Wei Jin and Md Saifuddin Faruk and Xingwen Yi and Jianming Tang},

url = {https://opg.optica.org/jlt/abstract.cfm?uri=jlt-43-18-8839},

year  = {2025},

date = {2025-09-01},

urldate = {2025-10-08},

journal = {Journal of Lightwave Technology},

volume = {43},

number = {18},

pages = {8839–8848},

publisher = {IEEE},

abstract = {Secure data transmission is experimentally demonstrated in a 1.67 Gb/s seamlessly converged fibre–millimeter wave (mmWave) network using the authors’ newly proposed chaotic digital filter (CDF)-based physical layer security (PLS) technique. The CDF-based encryption/decryption operates by introducing noise-like, key-dependent phase variations to conventional filter impulse responses. Validation is performed in a seamlessly converged network comprising a 25 km standard single-mode fibre (SSMF) link and a 5 m 36 GHz mmWave wireless link, utilizing cost-effective photonic-based mmWave generation and envelope detector-based reception. Experimental results show that the demonstrated PLS technique allows the encrypted signals to continuously flow between the fibre and radio frequency (RF) domains. The PLS technique also supports simultaneous optical and radio frequency access with almost identical BER transmission performances, and power penalties of <1 dB. To gain an in-depth understanding of the measured results, the CDFs’ characteristics, including their chaotic nature, sensitivity to security keys and optimum CDF design parameters, are explored both theoretically and experimentally in detail. The optimum security key properties and CDF's filter lengths are identified, which are independent of the transmission media and major characteristics of the encrypted signals. The CDF-based PLS technique offers salient advantages of ‘security-by-design’, ‘openness-by-design’, ‘dynamic security at the traffic level’, and ‘universal network compatibility’.},

note = {Publisher: IEEE},

keywords = {Bit error rate, Frequency division multiplexing, Optical signals, Phase noise, Quantum key distribution, Single mode fibers},

pubstate = {published},

tppubtype = {article}

}

@article{vallejo_seamlessly_2025,

title = {Seamlessly Converged Fiber-Wireless Access Networks With Dynamic Sub-Wavelength Switching and Tunable Photonic mmWave Generation},

author = {Luis Vallejo and Omaro Fawzi Abdelhamid Gonem and Wei Jin and Roger Philip Giddings and Lin Chen and Yi Huang and Xingwen Yi and Md Saifuddin Faruk and Jianming Tang},

url = {https://opg.optica.org/jlt/abstract.cfm?uri=jlt-43-6-2624},

year  = {2025},

date = {2025-03-01},

urldate = {2025-10-08},

journal = {Journal of Lightwave Technology},

volume = {43},

number = {6},

pages = {2624–2635},

publisher = {IEEE},

abstract = {For implementing next-generation radio access networks (NG-RANs) supporting services/applications in the beyond-5G (B5G) era, seamless fiber-wireless network convergence is vital for enabling heterogeneous signals of various characteristics to continuously flow between the optical and electrical domains, i.e., the baseband unit (BBU) and user equipment (UE), without optical-electrical-optical (O-E-O) conversions or digital signal processing (DSP) at any intermediate nodes. To address such challenges, this paper proposes and experimentally demonstrates, for the first time, a cost-effective fiber-wireless converged flexible and dynamic access network based on intensity modulation and direct detection (IM-DD). The demonstrated network utilizes O-E-O conversion-free Soft-reconfigurable optical add/drop multiplexers (Soft-ROADMs) at remote nodes to dynamically establish connections between the BBU and the remote radio heads (RRHs) at the sub-wavelength level. In addition, free-running laser-enabled photonic millimeter-wave (mmWave) signal generation and passive electrical envelope detector-enabled mmWave down-conversion are also used, respectively, at the RRHs and UEs to achieve mmWave frequency tunability and adaptive wireless network coverage. The network performance and optimum network configuration are experimentally explored extensively in a fiber-wireless converged access network with 3 × 1.333 Gbps dynamic BBU-UE connections over a 10 km IM-DD fiber link and a 5 m, 38 GHz mmWave wireless link. The results show that wide mmWave frequency tuning ranges and adaptive mmWave coverages are achievable by just adjusting the RRH-laser frequency and output powers.},

note = {Publisher: IEEE},

keywords = {Frequency division multiplexing, Optical signals, Optical switching devices, Signal processing, Signal transmission, Variable optical attenuators},

pubstate = {published},

tppubtype = {article}

}

@article{vallejo_experimental_2025,

title = {Experimental investigation of a seamlessly converged fiber-wireless access network employing free-running laser- and envelope detection-based mmWave generation and detection},

author = {Luis Vallejo and Omaro Fawzi Abdelhamid Gonem and Wei Jin and Md Saifuddin Faruk and Roger Philip Giddings and Xingwen Yi and Jianming Tang},

url = {https://opg.optica.org/oe/abstract.cfm?uri=oe-33-1-604},

doi = {10.1364/OE.532694},

issn = {1094-4087},

year  = {2025},

date = {2025-01-01},

urldate = {2025-10-08},

journal = {Optics Express},

volume = {33},

number = {1},

pages = {604–618},

publisher = {Optica Publishing Group},

abstract = {Employing free-running laser/envelope detection-based millimeter wave (mmWave) signal generation/detection at remote radio heads (RRHs)/user equipment (UE) offers a cost-effective solution for seamlessly integrating existing intensity modulation-direct detection (IM-DD)-dominated optical access networks and wireless networks. Such fiber-wireless convergence enables a continuous flow of signals with varying characteristics between the baseband unit (BBU) and UE across fiber and wireless network segments without the need for optical-electrical-optical (O-E-O) conversions and digital signal processing (DSP) at intermediate nodes. In this paper, we extensively investigate the performance of such a fiber-wireless converged access network employing free-running laser/envelope detection-based mmWave generation/detection in an IM-DD-based 1.67 Gbit/s transmission system with 25 km standard single-mode fiber (SSMF) and 5 m @38 GHz mmWave wireless links. Experimental results demonstrate that both mmWave frequency tunability and adaptive mmWave network coverage are achievable by just dynamically and adaptively configuring the output wavelength and power of the RRH-embedded free-running laser. Additionally, envelope detection allows RRHs to use low-cost MHz-linewidth-level free-running lasers while maintaining excellent performance stability.},

note = {Publisher: Optica Publishing Group},

keywords = {Fiber networks, Frequency division multiplexing, Laser sources, Optical access networks, Optical network architecture, Optical signals},

pubstate = {published},

tppubtype = {article}

}