Hybrid Precoding for Millimeter Wave RoF Systems

Large propagation path loss and limited scattering of millimeter wave (mm-wave) channels create new challenges for physical layer signal processing. Hence, in this paper, we propose a photonic hybrid precoding model for mm-wave radio-over-fiber systems that overcomes hardware constraints on radio frequency precoding. With the help of analog photonic beamformers, the hybrid precoding strategy combats the large losses of mm-wave and mitigates inter-user interference, which in turn reduces the number of RF chains required to perform digital beamforming. The simulation results show that the proposed model can offer significant coding gains over conventional RF hybrid precoding systems. Unlike RF hybrid precoding systems, the photonic hybrid precoding systems can provide higher data rates and lower error rates in multi-user transmission scenarios.