1 Abstract—Network architectural changes to satisfy all the 5G+ mobile network specifications and requirements are necessary due to the popularization of streaming and cloud applications on omnipresent portable devices. The combination of massive installation of micro-cell antenna sites with the cloud access radio network (C-RAN) architecture has recently been nominated as a promising technology for high-capacity mobile fronthaul links, albeit at a high cost. An alternative approach for next-generation fronthaul networks is to utilize the already deployed passive optical networks (PONs) where wireless and wired services may coexist in a converged manner. Non-orthogonal multiple access (NOMA) modulation with multi-band carrierless amplitude and phase modulation (NOMA-CAP) has recently been investigated as a promising 5G+ modulation format candidate to increase the capacity and flexibility of future mobile networks. Here, we experimentally demonstrate the convergence of a NOMA-CAP wireless waveform with a single-carrier wired signal in a PON scenario using radio-over-fiber (RoF) technology. Specifically, fifteen NOMA-CAP bands, with two NOMA power levels to double the capacity, transmit 15 Gb/s multiplexed with a digital 10 Gb/s four-level pulse amplitude modulation (PAM-4) signal for downlink application. Two converged system implementations have been considered, first using electrical frequency division multiplexing (EFDM) and secondly using the hybrid EFDM- wavelength division multiplexing (EFDM-WDM). Successful transmission through a 25 km span of standard single-mode fiber is achieved with negligible transmission penalty for both proposed converged solutions. Index Terms—Mobile fronthaul convergence, multi-band carrierless amplitude and phase modulation, non-orthogonal multiple access, optical access networks, radio-over-fiber, successive interference cancellation. Manuscript received MM DD, AA; revised MM DD, AA; accepted MM DD, AA. This work was supported in part by ALLIANCE (TEC2017-90034- C2-2-R) project co-funded by FEDER, the European Union’s Horizon 2020 research and innovation programme under grant agreements no 761989 and 871900 (5G-PHOS and 5G-COMPLETE), as well as MINECO FPI-BES-2015- 074302. (Corresponding author: Samael Sarmiento.) Samael Sarmiento, Salvatore Spadaro and José Antonio Lázaro are with the School of Telecommunications Engineering, Polytechnic University of Catalonia, Barcelona 08034, Spain (e-mail:, samael.sarmiento@tsc.upc.edu; spadaro@tsc.upc.edu; jose.lazaro@tsc.upc.edu). I. INTRODUCTION wing to the immense increment of the network traffic due to novel multimedia streaming services and cloud services on personal devices, combined with future extensive machine- to-machine communication [1], network operators envision to deliver both broadband wireless and wireline services to final users through the already-deployed access network infrastructure. This approach minimizes both the capital expenditure (CAPEX) and the operation expenditure (OPEX) [2, 3]. Moreover, already deployed passive optical networks (PONs) are the most competitive solution to serve as mobile fronthaul, especially in cloud access radio network (C-RAN) scenarios where flexibility, low latency and high capacity are compulsory [4]. Furthermore, deployed PONs can be upgraded in a cost-effective way to concurrently support both wired and wireless services in a converged manner. C-RAN considers the division of the traditional base station into several only-transmitting, low-complexity and cheap remote radio heads (RRHs) and a single cloud-hub base band unit (BBU) located at the central office (CO), where complex processing is centralized. Open base station standard initiative (OBSAI) and common public radio interface (CPRI) are the transmission techniques used in 4G fronthaul networks. Nevertheless, these interfacing techniques are inadequate for high capacity and massive 5G/5G+ mobile communication services where high spectral efficiency is imperative. Ethernet- based CPRI (e-CPRI), which performs a digitization of the RF signal, is used in current 5G fronthaul network rollouts due to its higher efficiency, flexibility, and its low quantization resolution requirement. Moreover, e-CPRI is compatible with both telecom and enterprise networks enabling Xhaul José Manuel Delgado Mendinueta, Satoshi Shinada, Hideaki Furukawa and Naoya Wada are with the Photonic Network System Laboratory, National Institute of Information and Communication Technology (NICT), 4-2-1 Nukui- Kitamachi, Koganei, Tokyo 184-8795, Japan.(e-mail: mendi@nict.go.jp, sshinada@nict.go.jp, furukawa@nict.go.jp, wada@nict.go.jp). José Antonio Altabás is with Bifrost Communications, Scion DTU, Akademivej Bygnig 381, 2800 Kgs Lyngby, Denmark, and the Aragon Institute of Engineering Research, University of Zaragoza, Zaragoza 50018, Spain (e- mail:,jaltabas@unizar.es). Juan José Vegas Olmos is with Mellanox Technologies, Yokneam, 20692, Israel (e-mail: juanj@mellanox.com). High Capacity Converged Passive Optical Network and RoF-based 5G+ Fronthaul Using 4-PAM and NOMA-CAP Signals Samael Sarmiento, José Manuel Delgado Mendinueta, Member, IEEE, José Antonio Altabás, Salvatore Spadaro, Senior Member, IEEE, Satoshi Shinada, Member, IEEE, Hideaki Furukawa, Member, IEEE, Juan José Vegas Olmos, Senior Member, IEEE, José Antonio Lázaro, Member, IEEE, and Naoya Wada, Member, IEEE O