  Large propagation path loss and limited scattering of millimeter wave
(mmwave) channels create new challenges for physical layer signal processing.
Hence, in this article, we propose a photonic hybrid precoding model for mmwave
radio-over-fiber systems that overcomes hardware constraints on radio frequency
precoding. With help of silicon photonic integrated circuits (Si-PICs), the
photonic precoding strategy combats the large losses of mmwave and mitigates
inter-user interference. Simulation results show that the proposed model can
offer significant coding gains over conventional precoding systems.
