Multichannel 120-Gb/s Data Transmission Over 2 $,\times,$ 2 MIMO Fiber-Wireless Link at W-Band

We experimentally demonstrated a seamlessly integrated fiber-wireless system that delivers multichannel 120-Gb/s data through 80-km fiber and 2-m 2 $,\times,$ 2 multiple-input multiple-output (MIMO) wireless link at 92-GHz W-band adopting polarization division multiplexing quadrature phase shift keying (PDM-QPSK) modulation. The three-channel 3 $,\times,$ 40-Gb/s optical PDM-QPSK signals with 12.5-GHz channel spacing are simultaneously upconverted to 92-GHz wireless carrier by optical polarization-diversity heterodyne beating and then transmitted and received by two pairs of transmitter and receiver antennas, which form a full 2 $,\times,$ 2 MIMO wireless link. At the wireless receiver, a two-stage analog and digital downconversion is performed. Polarization and wireless 2 $,\times,$ 2 MIMO demultiplexing are realized by constant modulus algorithm based on digital signal processing. The bit-error ratio performance for the 120-Gb/s PDM-QPSK signal is measured after 80-km single-mode fiber-28 and 2-m wireless transmission.