Performance analysis of multiple radio-access provision in a multicore-fibre optical fronthaul

[EN] In this work we report a comprehensive experimental study targeting the dimensioning of the next-generation multicore-fibre (MCF) optical fronthaul employing space-division multiplexing (SDM). This fronthaul is capable of simultaneous provision of multiple radio-access technologies (multi-RATs) with advanced multi-antenna MIMO capabilities per RAT. The different parameters required for fronthaul dimensioning are evaluated considering state-of-the-art 4G LTE-Advanced altogether other legacy wireless standards in operation nowadays. In particular, the modulation characteristics, the antenna quality requirements (in terms of EVM, phase error or rho) and the signal-to-noise ratio (SNR) thresholds are evaluated employing fully-standard cellular signals transmitted on a multicore fibre (MCF) fronthaul. The study includes bi-directional signal transmission and multi-antenna MIMO multiplexing. The MCF optical fronthaul is evaluated with a multiplexed transmission of 2G, 3G, 3.9G and 4G MIMO signals in radio-over-multicore-fibre (RoMCF) employing a commercially available four-core MCF. The SNR requirements at the transmitter antenna are obtained for each cellular signal considering GSM, EDGE, EGPRS2-A, cdma2000 1xEV-DO, UMTS HSPA+ and LTE-Advanced standards. LTE-Advanced singleantenna and two-antenna systems implementing 2 x 2 MIMO transmission can be accomplished with SNR levels over 25 dB. In the case of LTE-Advanced 4 x 4 MIMO multiplexing over four cores of MCF media, 32 dB SNR is needed to achieve almost four times provided bitrate per user.This research was supported in part by Spain National Plan MINECO/FEDER UE TEC2015-70858-C2-1-R XCORE and GVA AICO/2018/324 NXTIC projects. The work of M. Morant is supported by Spain Juan de la Cierva, Spain IJCI-2016-27578 grant and Fundacion BBVA Leonardo 2018 HYPERCONN project.Morant, M.; Llorente, R. (2019). Performance analysis of multiple radio-access provision in a multicore-fibre optical fronthaul. Optics Communications. 436:161-167. https://doi.org/10.1016/j.optcom.2018.11.036S16116743

Next-Generation Optical Fronthaul Systems Using Multicore Fiber Media

(c) 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.This paper proposes and investigates the use of multicore fiber (MCF) media performing space-division multiplexed transmission for next-generation optical fronthaul systems. We report the experimental demonstration of combined radio-over-fiber (RoF) transmission of full-standard LTE-Advanced (LTE-A) and WiMAX signals providing fronthaul connectivity in 150m of 4-core fiber (4CF), transmitting simultaneously fully independent wireless services. Operating in linear and nonlinear optical power regimes, the experimental evaluation verifies that the error vector magnitude (EVM) is not degraded when intercore and intracore Kerr nonlinearities are excited in MCF with high input power levels. As a result, nonlinear regime is proposed as a key factor to reduce the temporal EVM fluctuation induced by the random nature of the intercore crosstalk in MCF. In addition, MCF fronthaul applied to converged fiber-wireless polarization multiplexed passive optical networks is demonstrated to transmit LTE-A and WiMAX signals over two orthogonal optical polarizations. The polarization-multiplexed signal is transmitted in RoF over 25.2 km of standard single-mode fiber and then demultiplexed and injected in different cores of the 4CF to provide fronthaul connectivity. Finally, the extension of multicore optical fronthaul capacity is proposed using MIMO LTE-A signals. The tolerance of the MIMO LTE-A RoF transmissions to in-band crosstalk is reported and compared to single-input single-output (SISO) configuration. The experimental results indicate that MIMO configuration is more tolerant than SISO to in-band crosstalk considering both internal and external interferences. MIMO and SISO configurations are compared when transmitted in RoF over a 4CF operating in linear and nonlinear regimes and core interleaving nonlinear stimulation is proposed to reduce the temporal and spectral EVM fluctuation when the same wireless standard is propagated in each core.This work was supported in part by Spain the National Plan Project XCORE TEC2015-70858-C2-1-R and RTC-2014-2232-3 HIDRASENSE. The work of A. Macho was supported by BES-2013-062952 F.P.I. Grant. The work of M. Morant was supported in part by UPV postdoc PAID-10-14 program.Macho-Ortiz, A.; Morant Pérez, M.; Llorente Sáez, R. (2016). Next-Generation Optical Fronthaul Systems Using Multicore Fiber Media. Journal of Lightwave Technology. 34(20):4819-4827. https://doi.org/10.1109/JLT.2016.2573038S48194827342

RoF data transmission using four linearly polarized vector Modes of a polarization maintaining elliptical ring core fiber

We experimentally investigate the feasibility of transmission of radio frequency (RF) signals over a 900 m polarization-maintaining, elliptical ring core fiber. No multiple-input multiple output (MIMO) processing is used to recover the RF signals carried by different modes; we recover the 16QAM, orthogonal frequency division multiplexing (OFDM) RF signals with the same techniques used for single mode fibers. For the first time, we report transmission of four RF streams over four channels in a few mode fiber. Also, for the first time, we transmit RF signals over two polarizations of a mode in few mode fibers and successfully recover data in both polarizations without polarization tracking or digital signal processing to separate polarizations. Furthermore, we examine the impact of fiber bending on crosstalk among channels. We show that even under severe bending, the polarization states remain separated and the RF streams transmitted on polarization states of a mode could be recovered with low power penalty

Multi-Core Optical Fibers: Theory, Applications and Opportunities

Multi-core fibers (MCFs) have sparked a new paradigm in optical communications, as they can significantly increase the Shannon capacity of optical networks based on single-core fibers. In addition, MCFs constitute a useful platform for testing different physical phenomena, such as quantum or relativistic effects, as well as to develop interesting applications in various fields, such as biological and medical imaging. Motivated by the potential applications of these new fibers, we will perform a detailed review of the MCF technology including a theoretical analysis of the main physical impairments and new dispersive effects of these fibers, and we will discuss their emerging applications and opportunities in different branches of science

High Capacity Mode Division Multiplexing Based MIMO Enabled All-Optical Analog Millimeter-Wave Over Fiber Fronthaul Architecture for 5G and Beyond

The ever-increasing proliferation of mobile users and new technologies, and the demands for ubiquitous connectivity, high data capacity, faster data speed, low latency, and reliable services have been driven the quest for the next generation, fifth generation (5G), of the wireless networks. Cloud radio access network (C-RAN) has been identified as a promising architecture for addressing 5G requirements. However, C-RAN enforces stringent requirements on the fronthaul capacity and latency. To this end, several fronthaul solutions have been proposed in the literature, ranging from transporting digitized radio signals over fiber and functional splits to an entirely analog-radio-over fiber (A-RoF) based fronthual. A-RoF is a highly appealing transport solution for fronthual of 5G and beyond owing to its high bandwidth and energy efficiency, low system complexity, small footprint, cost-effectiveness, and low latency. In this paper, a high capacity multiple-input-multiple-output (MIMO) enabled all-optical analog-millimeter-wave-over fiber (A-MMWoF) fronthaul architecture is proposed for 5G and beyond of wireless networks. The proposed architecture employs photonic MMW signals generation and mode division multiplexing (MDM) along with wavelength division multiplexing (WDM) for transporting MMW MIMO signals in the optical domain. In support of the proposed architecture design, a comprehensive state-of-the-art literature review on the recent research works in high capacity A-RoF fronthaul systems and related transport technologies is presented. In addition, the corresponding potential challenges and solutions along with potential future directions are highlighted. The proposed design is flexible and scalable for achieving high capacity, high speed, and low latency fronthaul links

Multiplexage par division modale pour les applications à courte distance

Le multiplexage par division de mode (MDM) a reçu une attention considérable de la part des chercheurs au cours des dernières années. La principale motivation derrière l'utilisation de différents modes de fibre optique est d'augmenter la capacité des réseaux de transport. Les expériences initiales ont montré une grande complexité dans le traitement de signal (DSP) du récepteur. Dans cette thèse, nous étudions la viabilité et les défis de la transmission de données sur des fibres à quelques modes (FMF) pour des systèmes MDM à complexité de DSP réduite. Nos études comprennent à la fois une transmission de données cohérente et non cohérente. Dans notre première contribution, nous démontrons, pour la première fois, la transmission de données sur 4 canaux dans une nouvelle fibre OAM sans démultiplexage de polarisation optique. Nous utilisons une complexité de DSP réduite: deux jeux d'égaliseurs MIMO (multiple-input multiple-output) 2 × 2 au lieu d'un bloc égaliseur MIMO 4 × 4 complet. Nous proposons un nouveau démultiplexeur de mode permettant de recevoir simultanément deux polarisations d'un mode et de réaliser électriquement un démultiplexage de polarisation dans le récepteur DSP. Nous étudions également la pénalité OSNR due aux imperfections dans le démultiplexeur de mode et nous examinons la vitesse de transmission maximum accessible pour notre système. Dans notre deuxième contribution, nous étudions les dégradations modales dans les systèmes OAM-MDM, en nous concentrant sur leur effet sur la performance et la complexité du récepteur. Dans notre étude expérimentale, nous discutons pour la première fois de l'impact de deux modes non porteurs de données sur les canaux de données véhiculés par les modes OAM. Deux types différents de fibres OAM sont étudiés. Nous caractérisons notre liaison MDM en utilisant les techniques de mesure du temps de vol et de réponse impulsionnelle. Nous discutons des conclusions des résultats de caractérisation en étudiant l'impact des interactions modales sur la complexité de l'égaliseur du récepteur pour différents scénarios de transmission de données. Dans le troisième chapitre, nous étudions un nouveau FMF à maintien de polarisation et conduisons deux séries d'expériences de transmission de données cohérentes et de radio sur fibre (RoF). Nous démontrons pour la première fois, la transmission de données sans MIMO sur six et quatre canaux dans les systèmes cohérents et RoF, respectivement. Nous démontrons également, pour la première fois, la transmission de données RoF sur deux polarisations d'un mode dans une FMF. Nous discutons de la dégradation des performances due à la diaphonie dans de tels systèmes. Nous étudions également l'impact de la courbure sur cette fibre dans un contexte de RoF. La propriété de maintien de polarisation de cette fibre sous courbure est étudiée à la fois par des expériences de caractérisation et de transmission de données.Mode division multiplexing (MDM) has received extensive attention by researchers in the last few years. The main motivation behind using different modes of optical fiber is to increase the capacity of transport networks. Initial experiments showed high complexity in DSP of the receiver. In this thesis, we investigate the viability and challenges for data transmission over specially designed few mode fibers (FMF) for MDM systems with reduced DSP. Our studies include both coherent and non-coherent data transmission. In our first contribution, we demonstrate, for the first time, data transmission over 4 channels in a novel OAM fiber without optical polarization demultiplexing. We use reduced DSP complexity: two sets of 2×2 multiple-input multiple-output (MIMO) equalizers instead of a full 4×4 MIMO equalizer block. We propose a novel mode demultiplexer enabling us to receive two polarizations of a mode simultaneously and conducting polarization demultiplexing electrically in receiver DSP. We also investigate the OSNR penalty due to imperfections in the mode demultiplexer and we examine the maximum reachable baud rate for our system. In our second contribution, we study the modal impairments in OAM-MDM systems, focusing on their effect on receiver performance and complexity. In our experimental study, for the first time, we discuss the impact of two non-data carrying modes on data channels carried by OAM modes. Two different types of OAM fibers are studied. We characterize our MDM link using time-of-flight and impulse response measurement techniques. We discuss conclusions from characterization results with studies of the impact of modal interactions on receiver equalizer complexity for different data transmission scenarios . In the third contribution, we study a novel polarization-maintaining FMF and conduct two sets of coherent data transmission and non-coherent radio over fiber (RoF) experiments. We demonstrate for the first time, MIMO –Free data transmission over six and four channels in coherent and RoF systems, respectively. We also demonstrate, for the first time, RoF data transmission over two polarizations of a mode in a FMF. We discuss the performance degradation due to crosstalk in such systems. We also study the impact of bending on this fiber in RoF context. The polarization maintaining property of this fiber under bending is studied both via characterization and data transmission experiments

High Dimensional Modulation and MIMO Techniques for Access Networks

Exploration of advanced modulation formats and multiplexing techniques for next generation optical access networks are of interest as promising solutions for delivering multiple services to end-users. This thesis addresses this from two different angles: high dimensionality carrierless amplitudephase (CAP) and multiple-input multiple-output (MIMO) radio-over-fiber (RoF) systems. High dimensionality CAP modulation has been investigated in optical fiber systems. In this project we conducted the first experimental demonstration of 3 and 4 dimensional CAP with bit rates up to 10 Gb/s. These results indicate the potentiality of supporting multiple users with converged services. At the same time, orthogonal division multiple access (ODMA) systems for multiple possible dimensions of CAP modulation has been demonstrated for user and service allocation in wavelength division multiplexing (WDM) optical access network. 2 x 2 MIMO RoF employing orthogonal frequency division multiplexing (OFDM) with 5.6 GHz RoF signaling over all-vertical cavity surface emitting lasers (VCSEL) WDM passive optical networks (PONs). We have employed polarization division multiplexing (PDM) to further increase the capacity per wavelength of the femto-cell network. Bit rate up to 1.59 Gbps with fiber-wireless transmission over 1 m air distance is demonstrated. The results presented in this thesis demonstrate the feasibility of high dimensionality CAP in increasing the number of dimensions and their potentially to be utilized for multiple service allocation to different users. MIMO multiplexing techniques with OFDM provides the scalability in increasing spectral effciency and bit rates for RoF systems. High dimensional CAP and MIMO multiplexing techniques are two promising solutions for supporting wired and hybrid wired-wireless access networks