Improvements in Radio over Fiber Links Using Polarization Multiplexing

The feasibility of 60 GHz radio over fiber (RoF) transmission using polarization multiplexing is paving the way to potential solutions for 5G networks. Polarization multiplexing (Pol-Mux) can be utilized to double the bandwidth efficiency which means to increase the capacity of radio over fiber links. Polarization multiplexing applies two orthogonal polarizations carrying different radio frequency signals in the same optical fiber, simultaneously. We discuss the major transmission impairments of RoF systems applying the Pol-Mux technique. We investigate the transmission problems of these links considering the polarisation mode dispersion (PMD) effects in the case when varying the carrier frequency, fiber length, modulation format, bit rate, etc. We investigate the cross-talk effect and its compensation which provides a significant improvement in the link performance. We analyze the quality of the N-QAM signal transmission using numerical simulation in single sideband-based Pol-Mux RoF system. At the end of this paper we discuss the influence of chromatic dispersion (CD) and polarization mode dispersion (PMD) on quality factor in the case of Pol-Mux method. This way we obtain an optimal adjustment based on the Q factor.