5G Mobile Wireless Access and Digital Channeling with RF Over Fiber for Long-Haul 64-QAM Communication

Abstract

This paper presents the experimental results of a novel radio-over-fiber (RFoF) architecture that is capable of transmitting data at 20 Gb/s over a 600 km fiber. Such high bit rates required by 5G systems for long-haul communication. This is accomplished by overcoming the limitation of single mode fibers (SMF) of power attenuation and chromatic dispersion. This is achieved by interspersing sections of the SMF with a dispersion compensating filter (DCF) and embedding midway of the fiber length with chirped fiber Bragg grating (CFBG). Moreover, the proposed approach is shown to enhance the total bandwidth over a long-haul gigabit passive optical network (GPON) using integrated channel coarse wavelength division multiplexing (CWDM). In the experiment, a 64-quadrature amplitude modulation (64-QAM) signal was modulated onto CWDM signal. With the proposed RFoF architecture the signal power received over a 600 km fiber is greater than a conventional optical architecture by 19 dB for identical applied input optical power of 20 dBm. This translates to significant power savings that can be achieved with the proposed architecture over existing architectures that should reduce the carbon footprint of long-haul optical communications systems. The optical receiver is shown to have a sensitivity of −28.3 dBm for a bit-error rate (BER) of 10−9. These results demonstrate the viability of the proposed RFoF architecture in providing significant improvement in the bit rate over a transmission distance.