Bidirectional SMF-FSO-5G NR wireless converged systems with polarization multiplexing technique to enhance transmission capacity

This study demonstrates a bidirectional single-mode fiber (SMF)-free-space optical (FSO)-5G new radio (NR) wireless converged system that combines polarization multiplexing and wavelength division multiplexing techniques to enhance transmission capacity. The system achieves an aggregate data rate of 800-Gb/s over a total transmission distance of 41.63-km, comprising 40-km of SMF, a 1.6-km FSO link, and a 27-m 5G NR wireless link. Experimental results indicate excellent transmission performance, with downlink bit error rates (BERs) of 8.13×10 -5 (x-pol) and 7.76×10 -5 (y-pol), and uplink BERs of 7.41×10 -5 (x-pol) and 7.08×10 -5 (y-pol), which are well below the forward error correction threshold of 3.8×10 -3 . The optimal error vector magnitudes (EVMs) for downlink transmission are 9.14% (x-pol) and 9.39% (y-pol), while the uplink achieves EVMs of 9.6% (x-pol) and 9.78% (y-pol). In contrast, using a unidirectional FSO link in the converged system results in significantly degraded BERs of 1×10 -3 (x-pol) and 7.59×10 -4 (y-pol), along with higher EVMs of 11.24% (x-pol) and 11.4% (y-pol) for uplink transmission. These findings emphasize the advantages of bidirectional FSO links in converged systems for enhancing transmission capacity, making them a promising solution for next-generation communication networks.