39 GHz Full-Duplex Transmission of MultiGb/s Subcarrier Multiplexing and 5G NR Signals over Fiber and Space for Industry 4.0
10 February 2022
We propose a stable full-duplex transmission of radio signals over a hybrid fiber and free-space optics (FSO) link for the 5G fixed wireless access networks to accelerate Industry 4.0 transformation. For downlink (DL), we transmit the 39 GHz upconverted multiband IF-based subcarrier multiplexing (SCM) signals with the variable quadrature amplitude modulation (QAM) allocations for multi-user service. As a proof-of-operation, we successfully demonstrate a transmission of 3-Gb/s SCM signals (1-Gb/s per user) over the hybrid channel. For uplink (UL), satisfactory performance for the transmission of 2.4-Gb/s 5G NR signal at 37-GHz over the mutual hybrid channel is experimentally achieved for the first time. The measured EVMs for both DL and UL signals with 4/16/64-QAM formats are well within the 3GPP requirements. We further evaluate the seamless bidirectional system in terms of received optical and RF powers, BERs and constellation diagrams. Considering the heavy rain in Spain, the predicted RF wireless distance for both DL and UL is approximately 200-m. Simulation results for DL are also shown to verify the superior performance of the variable over identical QAM allocations techniques. By using the former, up to five users (2-Gb/s per user) can be accommodated after 10-km fiber and 150- m FSO transmission.
