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The use of millimeter-wave (mm-wave) frequencies is required in order to support the increasing number of connected devices expected from the fifth generation (5G) of mobile communications. Subsequently, the generation of radio-frequency (RF) carriers ranging from 10 GHz to 300 GHz and their transport through optical distribution network (ODN) is a key element of the future 5G fronthaul. Optically assisted RF carrier generation is one of the most promising solutions to tackle this issue, allowing a wide use of analog radio-over-fiber (ARoF) architectures. However the main limitation of these optical methods is related to the finite coherence of lasers sources, which can dramatically degrade data transmission in analog formats. To mitigate its impact, the use of orthogonal frequency-division multiplexing (OFDM) as the 5G standard allows employing efficient phase noise compensation algorithms. Therefore, in this study, we present an experimental demonstration of a mm-wave generation technique based on an optical phase-locked loop (OPLL) that fulfills the frequency specifications for 5G. Then, an algorithm is introduced that improves data recovery at reception and reduces the impact of a possible high phase noise carrier. Finally, a back-to-back data transmission experiment is performed, demonstrating the efficiency of the algorithm to reach the 5G requirements. These results emphasize the use of OPLLs as a viable solution to generate mm-wave carriers for 5G and beyond.

Fifth-generation mobile networks (5G) is the established solution to satisfy the highly demanding key performance indicators such as traffic volumes, bit-rate, latency, and power consumption, among others of the future telecommunication infrastructure. The already saturated sub-6 GHz spectral band does not accommodate such requirements and forces the move towards higher frequencies, with the millimeter-wave (mm-wave) domain being an adequate band to operate. However, the exploitation of mm-wave signals in the mobile cells implies the deployment of an enormous quantity of small cells with associated equipment, footprint, and control. Thus, analog radio-over-fiber (ARoF) emerges as a suitable technology because of their attractive benefits such as low latency, low hardware complexity, and reduced power consumption. However, through investigation of experimental ARoF systems adhering to the 5G standard is scarce. Therefore, in this work, a novel and efficient bidirectional ARoF scheme based on multicore fiber (MCF) and oriented to 5G mm-wave communications is proposed and experimentally validated. The setup configurations are according to the 5G standard, enabling a wireless link at 26 GHz (n258, K-band) and time division duplex (TDD) communication. The proposed scheme is thoroughly evaluated under all the 5G numerologies and with different bandwidth settings. Moreover, key design considerations of the experimental testbed are explained and discussed to optimize the final yields of the system. The experimental results of both transmission directions are compared and analyzed, and prove the viability of the proposed bidirectional ARoF system as an excellent solution to be part of the future 5G mm-wave network.

Fifth-generation mobile networks (5G) are the solution for the demanding mobile traffic requirements, providing technologies that fulfill the requisites of different type of services. The utilization of the millimeter-wave (mm-wave) band is the straightforward technique to achieve high bit rates. Moreover, analog radio-over-fiber (ARoF) brings outstanding benefits such as low cost, low power consumption, and high spectral efficiency, among others. Thereby, mm-wave ARoF is a strong candidate to pave the way for common public radio interface (CPRI) in the fronthaul for the future 5G architecture. As orthogonal frequency-division multiplexing (OFDM) is the adopted waveform in the 5G standard, it should be also utilized in mm-wave ARoF systems for 5G. However, phase noise is one of the most degrading factors in mm-wave OFDM ARoF systems. Therefore, in this work, an analysis of the phase noise is carried out through an experimental setup up. The configuration of this setup enables to gradually modify the final phase noise level of the system. Furthermore, an original and novel algorithm to compensate the phase noise in OFDM receivers is proposed. The performance of this algorithm is experimentally evaluated through the setup for different phase noise levels and different subcarrier spacings. The obtained results show the effectiveness of the proposed algorithm under those conditions, highlighting the viability of mm-wave OFDM ARoF for 5G and beyond.

Analog radio-over-fiber (ARoF) technology has proven to be a promising solution to be part of the future millimeter-wave (mm-wave) 5G/6G architecture due to its attractive benefits such as simplified remote antenna units (RAUs), low-power consumption, and low cost. However, ARoF channels present hefty drawbacks, such as phase noise and nonlinear effects, that need to be addressed. The probabilistic amplitude shaping (PAS) technique is able to reduce the impact of such drawbacks, allowing a fine optimization of channel capacity usage. In particular, enumerative sphere shaping (ESS) implementation stands out as an excellent PAS approach because of its energy-efficiency and low complexity for short blocklengths. In this work, for the first time to the best of our knowledge, an ESS scheme is evaluated in an experimental bidirectional mm-wave ARoF setup oriented towards 5G communications. Furthermore, a novel soft ESS demapping algorithm is proposed and explained. The experimental results confirm the ESS technique, together with the proposed algorithm, as a convenient solution to enhance the channel capacity use of mm-wave ARoF systems for the 5G/6G fronthaul.

In this paper, we have demonstrated analog radio-over-fiber (A-RoF) transmission of 5G (256/512-QAM) and WiGig (64-QAM) signals in the millimeter-wave (mm-Wave) frequency range from 55 GHz - 65 GHz in a system with 10 km fiber and 1 m wireless channels. The system employs a hybrid integrated InP-Si3N4 dual laser module for flexible heterodyne operation in the V-band and a simplified system setup, with respect to our prior demonstrations. The experimental results show excellent performance with bit error ratio (BER) values as low as of 8.46×10-6 and 1.11×10-4, and lowest error vector magnitudes (EVMs) of 2.4 % and 6.1%, achieved for the 5G and WiGig signals, respectively.

Fifth generation (5G) is the emerging mobile communications platform that aims to meet the market requirements in terms of enhanced broadband connectivity based on harnessing small cell and mmWave technology. These two in synergy will provide high capacity gain not only through the hyperdense deployment of small cell but also through accessing large swathes of untapped spectrum at mmWave frequencies. The envisaged architecture entails an integrated optical wireless network architecture, where optical technology will complement radio in order to handle the new demands on capacity over the backhaul and fronthaul network, leading to the notion of analog radio over fiber (ARoF). The goal of this chapter is to provide novel approaches to optimize the performances of mmWave ARoF systems that includes developing enabling technology from a digital to signal processing (DSP) and device perspective.

This paper presents a beyond 5G fronthaul network with dynamic beamforming and -steering. The proposed fronthaul solution deploys optical beamforming (OBF) by combining space division multiplexing (SDM), analogue radio-over-fiber (ARoF), and the novel optical beam forming network (OBFN) technologies. From the service management and orchestration (MANO) point of view, the proposed fronthaul solution also deploys an advanced software defined networking (SDN) and Network Function Virtualization (NFV) control and orchestration architecture developed with the goal to optimally manage and reconfigure the physical layer resources (i.e., optical and radio) at the central office and cell sites (i.e., pool of baseband units (BBUs), remote radio heads (RRHs), ARoF transceivers and OBFNs). The proposed beyond 5G fronthaul architecture is primarily oriented to deploy massive machine-type communication (mMTC) services with high-bandwidth requirements, such as for industry 4.0. In this paper we experimentally validate the novel OBFN system, and the dynamic SDN/NFV MANO of the transport connectivity and network services for optical beamforming. The obtained experimental results show that the overall delay for the provisioning and removal of an OBF service, considering the contribution of the involved optical and radio systems and the SDN/NFV MANO layer, is 134s and 18s respectively. The reconfiguration of the OBF service to add or remove a beam can be performed in the range of 65–87s.

This work studies and experimentally evaluates the performance enhancement by using PS-OFDM in a 5G mm-Wave ARoF system at 25 GHz for all 5G numerologies and with different phase noise levels.

This work studies and experimentally evaluates the performance enhancement by using PS-OFDM in a 5G mm-Wave ARoF system at 25 GHz for all 5G numerologies and with different phase noise levels.

We experimentally analyze the ARoF based on OPLL mm-Wave generation performance for 5G fronthaul. Remarkable performance improvements are achieved for all 5G NR numerologies and different OPLL configurations despite their inherently high phase noise level.

We experimentally analyze the ARoF based on OPLL mm-Wave generation performance for 5G fronthaul. Remarkable performance improvements are achieved for all 5G NR numerologies and different OPLL configurations despite their inherently high phase noise level.

Fifth-generation (5G) mobile networks consist of a range of novel technologies to fulfill different and exigent requirements and serve a wide range of services. To reach this, analog radio over fiber (ARoF) fronthaul with millimeter-wave (mm-wave) cells is a firm candidate to be part of the 5G architecture. Nonetheless, combined mm-wave and ARoF systems present new challenges such as high free-space path loss (FSPL), phase noise, chromatic dispersion, and other impairments. Therefore, the selection of the modulation format is crucial to reduce these effects and their impact. This work compares and analyzes different modulation formats in this type of system in order to choose the best waveform candidate for mm-wave 5G and beyond with ARoF fronthaul. An experimental comparison of OFDM, SC-FDM, UFMC, GFDM, and multi-CAP, shows that the standard OFDM may not be the best choice for mm-wave 5G.

We demonstrate two advanced services deployed in a novel SDN/NFV optical fronthaul network combining analog radio over fiber (ARoF) and power over fiber (PoF); vertical service management for virtual content delivery networks (vCDNs), and user mobility and remote optical power management for femto cells., Grant numbers : AURORAS - Autonomic and disaggregated optical networks leveraging edge computing and photonic technologies (RTI2018-099178-B-I00).

This paper presents the novel SDN/NFV 5G fronthaul network scenarios deployed in the blueSPACE project. blueSPACE envisions the upgrade of the fronthaul network to include optical SDM transmission for further increasing the network capacity. One of the novelties is the introduction of ARoF transceivers to reduce the 5G fronthaul bandwidth requirements, in addition to the DRoF solutions that are used for the 4G fronthaul interface and the 3GPP's NGFI. Moreover, ARoF transceivers enable to develop optical beamforming technologies for beam steering and multi-beam transmission. Finally, power of fiber solutions to remotely feed small cells are also considered.

Tyrosine feedback-inhibits the 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase isoenzyme AroF of Escherichia coli. Here we show that an Asn-8 to Lys-8 substitution in AroF leads to a tyrosine-insensitive DAHP synthase. This mutant enzyme exhibited similar activities (v=30-40 U mg(-1)) and substrate affinities (K(m)(erythrose-4-phosphate)=0.5 mM, positive cooperativity with respect to phospho(enol)pyruvate) as the wild-type AroF, but showed decreased thermostability. An engineered AroF enzyme lacking the seven N-terminal residues also was tyrosine-resistant. These results strongly suggest that the N-terminus of AroF is involved in the molecular interactions occurring in the feedback-inhibition mechanism.

We experimentally analyze the ARoF based on OPLL mm-Wave generation performance for 5G fronthaul. Remarkable performance improvements are achieved for all 5G NR numerologies and different OPLL configurations despite their inherently high phase noise level.