Enhanced Capacity of Radio over Fiber Links Using Polarization Multiplexed Signal Transmission

The future vision of integrating back- and front-haul in 5G mobile networks requires the design of high capacity transport architectures. To achieve this progress we suggest the application of the radio over fiber (RoF) technology for 5G back- and front-haul access links. Our proposed design is based on the coherent polarization multiplexed (Pol-Mux) technique. To understand the properties of polarization mode dispersion (PMD) we present the impact of PMD on the link quality factor with varying fiber length, bit rate, and PMD coefficient. To increase the capacity of the radio over fiber link we propose a new conversion method utilizing polarization controllers and the polarization beam combiners. Applying the new method 40 Gbit/s QPSK and 16-QAM signals are converted to coherent polarization multiplexed (Pol-Mux) signals. In the Pol-Mux approach the polarization cross talk can cause a significant impairment. However, with sufficient polarization extinction ratio this effect can be reduced substantially. Our simulation results reveal that the Pol-Mux approach yields better performance e.g. in terms of high data rates, and this way can significantly increase the link capacity for 5G access and core network functions.