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A bidirectional wavelength division multiplexing (WDM) analog radio-over-fiber (A-RoF) mobile fronthaul (MFH) link is enhanced using photonic integrated devices. Two key photonic integrated devices are combined in the A-RoF link: an 8-channel InP directly modulated laser (DML) transmitter and a 32×100-GHz silicon array waveguide grating (AWG). The DML transmitter has 8 parallel monolithically integrated distributed feedback lasers, enabling cooperative and reconfigurable downlink analog transmission. Moreover, the 32×100-GHz AWG is featured by low insertion loss (

We present a novel technique for dispersion compensation by exploiting the filtering properties of a fully reconfigurable serially coupled microring resonator (MRR) structure in analog intermediate frequency-over-fiber/mmWave (IFoF/mmWave) fiber/wireless 5G and beyond 5G(B5G)-oriented mobile fronthaul. To this extend, we demonstrate simulation and experimental results on analog photonic processing of 1 Gbaud quadrature phase shift keying (QPSK) modulated radio signal. By tuning filter's bandwidth in the range of 14–69 GHz, and resonance within a resonance free spectral range (FSR) range, dispersion induced power fading mitigation was achieved, for a set of widely adopted intermediate frequencies (IFs) and transmission distances. Analytical calculations carried out in MATLAB environment, highlighting significant improvement of transmission system output power, whereas are verified via transmission system simulations, resulting to error vector magnitude (EVM) improvement up to ∼ 30%. Experimental results verified both analytical and transmission simulation results for a series of IFoF downlink transmission system configurations. For widely used wireless transmission configuration at 8.5 GHz IF, by tuning the filter to appropriate bandwidth of 14 GHz and resonance peak properly, successful fiber wireless transmission for over 25 km of fiber was demonstrated, achieving 16.9% EVM for QPSK, below the 3GPP (<17.5%) requirements for 5G NR. [ABSTRACT FROM AUTHOR]

Towards relieving the bandwidth limitations in 5G mobile fronthaul networks, a Fiber Wireless (FiWi) small cell architecture is presented, relying on spectrally efficient analog transport on intermediate frequency over fiber (IFoF) and a millimeter wave (mmWave) phased array antenna (PAA) interfaced with a low-loss optical add/drop multiplexer (OADM) on Si3N4/SiO2 TriPleX platform with 5 dB fiber-to-fiber losses. Specifically, four 1 Gb/s FiWi links, each carrying a 250 MBd 16-QAM signal on 5.8 GHz IFoF, are wavelength division multiplexed (WDM) and transported across a 10 km Single Mode Fiber (SMF), before being demultiplexed into the constituent channels in the OADM device and subsequently wirelessly transmitted by the PAA over a 1 m-long V-band link with 90° degree beamsteering capability. Featuring 4x 1Gb/s user rate with beamsteering to meet the respective 5G key performance indicator (KPI) for the peak user rate and an EVM within the acceptable 3GPP limit of 12.5%, the current work forms the first centralized FiWi point-to-multipoint small cell architecture with efficient transport scheme on IFoF and ubiquitous 360°-degree coverage for emerging 5G mmWave networks. [ABSTRACT FROM AUTHOR]

Towards the 5G millimeter Wave (mmWave) era, analog transport offers a spectrally efficient scheme for converged Fiber Wireless (FiWi) networks. Signal integrity is traditionally considered as a limiting factor due to various non-linearities attributed to the microwave photonic link, expected to be further exacerbated by the RF-chain of beamforming Phased Array Antennas (PAAs). The letter proposes the end-to-end evaluation of FiWi analog links as unified communication channels rather than separately for the radio or optical part, presenting a link with a 32-element 60 GHz PAA, 1 m V-band distance, 10 km fiber and 10 dB dynamic range. The measurements reveal a third order Intercept Point (IIP3) of 4.8 dBm, compared to 22.8 dBm exclusively for the optics, pinpointing the V-band radio as the main source of degradation rather than the microwave photonic link. Single user uplink is also benchmarked using 300 Mbd QPSK, 250 16-QAM and 100 Mbd 32-QAM, achieving data-rate up to 1 Gb/s and beamsteering of 120° degrees. [ABSTRACT FROM AUTHOR]

We experimentally demonstrate a multi-user Fiber Wireless IFoF/mmWave uplink comprising a 32-element 60 GHz Phased Array Antenna (PAA) and 10 km of fiber for 5G fronthaul networks, supporting beamsteering within a 120° sector and 0.6 Gb/s uplink capacity within a 5 dB bandwidth of 2 GHz. The flexibility of the link is highlighted in two 3-user scenarios with 0.6 Gb/s uplink traffic: A Frequency Division Multiplexing (FDM) scheme with the PAA receiving isotropically at different frequencies and a Spatial Division Multiplexing (SDM) scheme where the same V-band frequency is re-used by all three users but are selectively received by the PAA using beamsteering. Error-free transmission with 100 Mbaud QPSK per user is demonstrated for both cases, forming the first comparison of FDM and SDM towards multi-user 5G mmWave/IFoF networks. [ABSTRACT FROM AUTHOR]

A Wavelength Division Multiplexing (WDM)-enabled analog mobile fronthaul architecture is presented supporting enhanced flexibility by exploiting the fine filtering properties of a fully reconfigurable, silicon photonics-based filtering element. Numerical studies are presented emphasizing on the flexibility, low-energy consumption, and the compatibility of our proposed chip-scale implementations with the analog Radio over Fiber (RoF)-based mobile transport. Proof-of-concept analog photonic processing of 1 Gbaud Quadrature Phase Shift Keying (QPSK)-modulated radio is successfully demonstrated through RoF transmission experiments. The integration of the analog mobile fronthauling segment in a WDM-enabled, Reconfigurable Optical Add/Drop Multiplexers (ROADM)-assisted fronthaul/midhaul infrastructure supporting low-latency edge computing is also discussed. [ABSTRACT FROM AUTHOR]

We experimentally demonstrate a multiband intermediate frequency-over-fiber/mmWave (IFoF/mmWave) fiber/wireless mobile fronthaul link for gigabit capacity over the unlicensed V-band (57–64 GHz). Digital synthesis of the multiband radio waveforms is performed at the baseband unit using digital subcarrier multiplexing technique, whereas digital predistortion is exploited to cope with the analog IFoF channel impairments without any further baseband processing at the digital-free remote radio head. Commercial optoelectronic components and analog V-band radio and antenna equipment for 7-km fiber and 5-m wireless transmission are employed to successfully demonstrate both uplink and downlink connectivity. An aggregate capacity up to 24 Gb/s was demonstrated with a 6-band 1 Gbaud 16-QAM on a 7.2-GHz analog bandwidth over the combined fiber/wireless channel showing error vector magnitude (EVM) values below the 3GPP requirements (<12.5%) for 5G systems. Multiformat assignment on each subcarrier was also realized by using M-PSK and 16-QAM schemes to achieve 18-Gb/s connectivity for both uplink and downlink, while demonstrating flexible resource allocation capabilities. By replacing the stand-alone optical modulator with an InP-based externally modulated laser chip for the implementation of the IFoF transmitter, a 16-Gb/s aggregate capacity was showcased on a 7-km fiber link and 5-m wireless channel with a 4-band 16-QAM encoded at 1 Gbaud. Successful operation with robust EVM performance was demonstrated using also the 6-band scheme of 1 Gbaud QPSK bands. [ABSTRACT FROM AUTHOR]

WDM-PON has been considered a promising solution for future fronthaul links concerning new mobile networks applications. However, in order to avoid inventory problems and reduce operation costs, there is a need for colorless sources, where the same basic optical source can be used regardless of the desired wavelength. Also, the digital RoF scheme, which has been employed so far, might require a bandwidth that is prohibitive even for optical fiber links. In this paper, we propose and numerically investigate a bidirectional colorless WDM-PON fronthaul transporting analog RoF signals as an alternative to meet these demands. All simulations were performed using a framework calibrated with experimental data. For the downstream, we employ a double-cavity self-seeding technique, while the upstream is performed by a cascaded-RSOAs carrier-reuse approach. BER and EVM simulation analysis are presented for various data rates, modulations formats and RF bands ranging from 1 to 5 GHz, demonstrating the feasibility of our proposed topology as a novel fronthaul approach. [ABSTRACT FROM AUTHOR]

Abstract WDM-PON has been considered a promising solution for future fronthaul links concerning new mobile networks applications. However, in order to avoid inventory problems and reduce operation costs, there is a need for colorless sources, where the same basic optical source can be used regardless of the desired wavelength. Also, the digital RoF scheme, which has been employed so far, might require a bandwidth that is prohibitive even for optical fiber links. In this paper, we propose and numerically investigate a bidirectional colorless WDM-PON fronthaul transporting analog RoF signals as an alternative to meet these demands. All simulations were performed using a framework calibrated with experimental data. For the downstream, we employ a double-cavity self-seeding technique, while the upstream is performed by a cascaded-RSOAs carrier-reuse approach. BER and EVM simulation analysis are presented for various data rates, modulations formats and RF bands ranging from 1 to 5 GHz, demonstrating the feasibility of our proposed topology as a novel fronthaul approach.