###### Abstract
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 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. Alternatively, free-space optical (FSO) technology has also shown potential for 5G transport network deployment using the unlicensed terahertz bands [18; 19]. For instance, [PERSON] et al. successfully reported a hybrid RoF/FSO fronthaul approach in which 5G coexists with 4G by means of coarse wavelength division multiplexing (CWDM) [19]. These previous works considered wireless links operating at a variety of radiofrequencies for providing mobile access, which might be either indoor or outdoor. Overall, RF links correspond to the main technical solution employed for access, although visible light communications (VLC) have also been recognized as an alternative for indoor environments, particularly when RF electromagnetic interference must be avoided [20; 21]. Apart from a tiny segment of the worldwide market already using VLC, wireless access networks are almost entirely based on electrical solutions, with approximately 70%of macrosites in the world being connected by microwave fronthauls. Although there are many published works investigating individual proposals regarding fronthaul solutions, only a few of them present comparisons between different optical-based fronthaul solutions [22; 23]. To the best of our knowledge, work addressing and confronting diverse electrical- and optical-based fronthauls is still missing in the specialized literature. In this context, the current study relies on integrating optical and wireless techniques towards novel fronthaul and access architectures in a NSA 5G NR framework, as proposed in Figure 1. In other words, we report implementations and comparison of diverse MWP techniques towards a non-standalone 5G NR optical-wireless communications (OWC) architecture in such a way that a variety of integrated services may be offered according to the network operator needs. The main contributions of this study are as follows: proposal and implementation of optical-wireless architectures applied to the NSA 5G NR framework; evaluation of diverse transport and access network solutions, including 5G NR dual wireless and FSO-based fronthaul, 4G/5G NR fiber-wireless fronthaul, combined fiber-optic and FSO-based 5G fronthaul, and 4G/5G NR VLC-based access network; discussion of experimental results regarding 4G and 5G coexistence at Gbit/s throughput and error vector magnitude (EVM) in accordance with 3 GPP Release 15. The focus of our work is data transmission in the physical layer, although Figure 1 provides a unifying view of our applications in a single ecosystem. The rest of the paper is structured as follows. In Section 2, we address different fronthaul configurations. First, in Section 2.1, a dual wireless and FSO-based fronthaul that enables a backup link for high-reliability services is reported. In Section 2.2, a RoF-based fronthaul is demonstrated for simultaneous RF signal distribution at distinct spectral bands. Unlike previous works [7; 8], a single wavelength is used to simultaneously cover 4G and 5G NR applications, including millimeter-wave bands. Next, in Section 2.3, we discuss a RoF/FSO-based fronthaul that enables high-capacity fronthaul extension for regions where optical fibers cannot be deployed all the way.