An Experimental Study on Polarization-Multiplexed Analog RoF Transmission

Analog radio-over-fiber (A-RoF) is expected to be a key technology for next-generation mobile fronthaul (MFH) because of its high economic feasibility and easy installability. As a method to expand the capacity of A-RoF-based MFH, we experimentally study polarization-multiplexed (POLMUX) transmission of A-RoF signals. In the 10-km single-mode fiber transmission of POLMUX $2 \times 2$ MIMO spatial streams, we occasionally observed difficulty in estimating channel state information. This is probably caused by two reasons: the optical power imbalance after polarization separation at the receiving end, and the reduction of the channel degrees of freedom due to two output signals being identical.