Performance Evaluation of Full-Duplex MIMO Seamless Fiber–Wireless System in $W$ -Band

We present a full-duplex fiber–wireless system in the $W$ -band for simultaneous transmission of multiple-input multiple-output (MIMO) signals in downlink and uplink directions. The proposed system uses wavelength-division multiplexing in the optical link and parallel-aligned/orthogonally aligned antenna polarizations in the wireless link for the MIMO and full-duplex signal transmission. Satisfactory performance is experimentally confirmed for $2\times 2$ MIMO OFDM and LTE-A signals in both directions. The system is highly spectral-efficient and scalable for large-scale MIMO signal transmission.