Photonic Wireless Links for 5G Broadband Access Networks

This paper presents a real-time demonstration of all-optical broadband photonic wireless downlink and uplink transmissions at the K-band with data rates of 16-Gb/s and 4 to 12-Gb/s, respectively. The experimental configuration is comprised of optical fiber and RF wireless channel with a successful transmission and detection of 4 GHz 16-quadrature amplitude modulated (QAM) wireless signals at 25 GHz over 2-m of wireless distance in the downlink using photonic heterodyning of a low noise monolithic quantum dash (QD) passively mode-locked laser (MLL), whereas in the uplink, a single wavelength laser is employed together with an optical intensity modulator to transmit 4/16/64-QAM signals with 2 GHz bandwidth. For both downlink and uplink, error vector magnitude (EVM) of lower than the standard requirements of 17.5%, 12.5% and 8% is achieved for 4, 16, and 64-QAM signals, respectively.

I. Introduction

The demand for broadband high speed wireless links driven by the diverse range of 5G applications have initiated the need for the utilization of high radio frequency (RF) bands including higher microwave and millimeter-wave bands with sufficient available spectrum. In order to fully exploit this promising 5G new radio (NR) resource and to alleviate the electronics bottleneck, microwave photonics with radio-over- fiber (RoF) is considered a key-enabling technology [1]. Therefore, photonic up/down conversion of broadband RF wireless signals over optical links using optical heterodyning has recently gained more interest and several new methods and photonic components have been developed for signal processing of RF signals. QD MLL based coherent frequency combs (CFC) offer low cost and flexible solution for photonic up/down conversion of large bandwidth and ultra-high speed RF signals.