Multiband and Photonically Amplified Fiber-Wireless Xhaul

Abstract

We propose and report the implementation of a multiband and photonically amplified fiberwireless (FiWi) Xhaul based on radio over fiber (RoF) technology and four-wave mixing (FWM) nonlinear effect, aiming 5G applications. The proposed ultra-wideband approach enables to simultaneously transport and amplify multiple radiofrequency (RF) signals through optical links, which might be employed as backhaul, midhaul or fronthaul of cellular systems. The FWM effect, originated from the use of 35m highly nonlinear fiber piece, gives rise to RF gain, when compared to conventional RoF (CRoF) systems. We demonstrate our technique allows replacing two conventional RF amplifiers with enhanced digital performance and/or significantly increasing the system throughput in 2.4 times, attaining 12 Gbit/s. Furthermore, a dual-band (7.5 and 28.0 GHz) wireless fronthaul, preceded by a 12.5-km optical midhaul, illustrates the multiband and photonically amplified FiWi Xhaul, by means of providing performance in terms of root mean square error vector magnitude (EVM RMS) in accordance to the 3GPP recommendations and at low phase noise level. INDEX TERMS 5G networks, four-wave mixing, microwave photonics, optical-wireless networks.

Brillouin Effect Impact in RoF Systems with Photonic-Assisted RF Amplification

“…According to the literature, Wall and Foster reported microwave amplification in A-RoF systems using FWM and reported 9 dB photonics-based RF gain for frequencies up to 14 GHz [20]. Our research group has intensely contributed to this topic in the last years [21][22][23][24][25], attaining world records in terms of maximum photonics-assisted RF gain of 27 dB and widest bandwidth up to 50 GHz. Particularly in [21] and [22], we have demonstrated the physical mechanism behind PAA, which not only due to the FWM effect, but also to the modulation sidebands enhancement.…”

“…10 exhibits the optical spectrum at the HNLF output, measured by an optical spectrum analyzer (OSA) with 0.07 nm resolution. The EDFA output power has been properly set to 20 dBm, which is a typical power for the PAA technique [25]. One can observe the two laser wavelengths (1,555.35 and 1,557.65 nm) and a considerable FWM products generation.…”

“…Afterward, the PAA technique has been improved and experimentally evaluated as a function of diverse parameters and figures of merit, as following [23] [24]: pump wavelength spacing, polarization voltage (Vbias) of a Mach-Zehnder modulator (MZM); RFdriven signal level; signal-to-noise ratio (SNR); phase noise; root mean square error vector magnitude (EVMRMS); spuriousfree dynamic range (SFDR); temperature variation. Recently, we have proposed a novel PAA approach based on a single pump, as well as the implementation of multiband and photonically amplified fiber-wireless Xhaul [25].…”

Integrating Optical and Wireless Techniques towards Novel Fronthaul and Access Architectures in a 5G NR Framework

“…Our research group has been intensely investigating A-RoF solutions for multiband and Gbit/s 5G systems in recent years [14][15][16][17]. The solution presented in [14] takes advantage of an operating gigabit passive optical network (GPON) from a local Internet service provider to distribute 5G-like signals, thus making use of an existing network infrastructure for 5G fronthaul in accordance with C-RAN.…”

“…The solution presented in [14] takes advantage of an operating gigabit passive optical network (GPON) from a local Internet service provider to distribute 5G-like signals, thus making use of an existing network infrastructure for 5G fronthaul in accordance with C-RAN. The approaches presented in [15,16] explore optical link not only for data transmission but also as a medium to perform photonics-assisted RF amplification. In [17], a dual-band wireless fronthaul using an FSS-based focal point/Cassegrain antenna assisted by an optical midhaul was demonstrated.…”