Photonic Precoding for Millimeter-Wave Multicell MIMO in Centralized RoF System

We propose a centralized photonic precoding method for millimeter-wave (MMW) multicell multiple-input multiple-output (MIMO) wireless communications. By applying the multicell MIMO and hence exploiting the spatial multiplexing gain over MMW, the system capacity is enhanced compared with the conventional single-input single-output (SISO) system. Based on radio-over-fiber (RoF) techniques, the multicell function is realized in a centralized location, which simplifies the design of remote access units. Traversing over the optical links enabled by the RoF infrastructure, we implement a novel method of photonic precoding to realize the zero-forcing precoding approach, which simplifies the user equipment complexity. A two-cell MIMO downlink transmission using the proposed method is experimentally demonstrated. Our results show that original signals can be directly recovered at the receivers with a power penalty <;1 dB compared with SISO transmission. The effect of varying photonic parameters is also analyzed.