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.