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Centralized Radio Access Network (C-RAN) comprises one of the main technologies for high capacity and low latency fronthauling in 5G networks. In this paper, we propose and evaluate an optical fronthaul 5G C-RAN architecture that targets to meet the bandwidth, latency and energy requirements of high traffic hot-spot areas. The proposed architecture employs Intermediate-Frequency-over-Fiber (IFoF) signal generation by Photonic Integrated Circuit (PIC) Wavelength Division Multiplexing (WDM) optical transmitters at the Base-Band Unit (BBU), while a novel design of Reconfigurable Optical Add-Drop Multiplexers (ROADMs) is used at the Remote Radio Head (RRH) site. An aggregate capacity up to 96 Gb/s has been reported by employing two WDM links with 4-band Orthogonal Frequency Division Multiplexing (OFDM) 64-QAM 0.5 Gbaud signals, showing error vector magnitude performance within the acceptable 8% limit. The physical layer evaluation of the proposed fronthaul is also extended with the evaluation of the network throughput and mean packet delay latency, using a Medium Transparent-Medium Access Control (MT-MAC) protocol, which employs gated service indicating latencies below 10ms.

We demonstrate the first all-optical digital physical-layer network coding (AOPNC) for Differential Phase Shift Keyed (DPSK) Sub-Carrier Modulated (SCM) signals in mm-wave Radio-over-Fiber (RoF) networks. AOPNC is performed at the Central Office (CO) by employing a Delay Interferometer (DI) for phase-to-amplitude conversion, two Semiconductor Optical Amplifier-Mach Zehnder Interferometers (SOA-MZIs) performing the XOR and XNOR operation between the OOK converted signals and a third SOA-MZI for the phase regeneration of the encoded phase-formatted XOR signal. Encoding and decoding are evaluated via simulations for 2.5 Gb/s NRZ-DPSK data modulated on 60 GHz SC for both synchronous and asynchronous operation.

High-performance server boards rely on multi-socket architectures for increasing the processing power density on the board level and for flattening the data center networks beyond leaf-spine architectures. Scaling, however, the number of processors per board and retaining at the same time low-latency and high-throughput metrics puts current electronic technologies into challenge. In this article, we report on our recent work carried out in the H2020 projects ICT-STREAMS and dREDBox that promotes the use of Silicon Photonic transceiver and routing modules in a powerful board-level, chip-to-chip interconnect paradigm. The proposed on-board platform leverages WDM parallel transmission with a powerful wavelength routing approach that is capable of interconnecting multiple processors with up to 25.6 Tbps on-board throughput, providing direct and collision-less any-to-any communication between multiple compute and memory sockets at low-energy 50 Gbps OOK line-rates. We demonstrate recent advances on the Si-based WDM transceiver, cyclic AWGR router and polymer-based electro-optical circuit board key-enabling technologies, discussing also potential applications in disaggregated rack-scale architectures. We also demonstrate our recent research on optical RAM technologies and optical cache memory architectures that can take advantage of the on-board interconnect technology for yielding true disintegrated computing resolving both power and memory bandwidth bottlenecks of current computational settings.

Future broadband access networks in the 5G framework will need to be bilateral, exploiting both optical and wireless technologies. This paper deals with new approaches and synergies on radio-over-fiber (RoF) technologies and how those can be leveraged to seamlessly converge wireless technology for agility and mobility with passive optical networks for stability, extended coverage and ultra-high speeds. The proposed convergence paradigm is based upon a holistic network architecture mixing mm-wave wireless access with photonic integration, dynamic capacity allocation and network coding schemes to enable high bandwidth fixed and 60GHz wireless personal area communications for gigabit rate per user. We have evaluated the link between the central office (CO) and the access point module (APM) of the proposed architecture by using both SCM OOK-SSB and BPSK modulation formats obtaining error free transmission for 40 km and 15 km respectively for power penalties below 2 dB while the concept was investigated for data rates up to 2.5 Gb/s and SC frequencies up to 60 GHz. In parallel a new optical network coding scheme is reported and demonstrated for SCM-based signalling to enhance bandwidth utilization and facilitate optical-wireless convergence in 5G applications.

We propose and experimentally demonstrate the first all optical digital network coding between OOK-NRZ Subcarrier Modulated (SCM) signals for Radio over Fiber (RoF) networks using a Semiconductor Optical Amplifier-Mach Zehnder Interferometer (SOA-MZI) as an XOR encoder. Successful encoding and decoding is demonstrated for 1 Gb/s data on a 10 GHz sub-carrier for synchronous and asynchronous NRZ data.

We present a heterogeneous passive WDM RoF system that is capable of simultaneously delivering broadband wireless 500 Mb/s services at 5 GHz RF carriers and 2.5 Gb/s LAN traffic at 60 GHz RF carriers over a standard single mode fiber. Our system employs phase modulation formats and optical frequency multiplication in order to increase the transmission distance and reduce the chromatic dispersion, allowing also for the use of cost-effective low-frequency RF components at the CO premises. Detailed performance evaluation results are derived by means of simulations that confirm the successful transmission of both RF carriers with less than 2 dB power penalty over a long distance optical path. The proposed system is fully compatible with the requirements of Medium-Transparent MAC protocols proposed for seamlessly and dynamically allocating resources in 60 GHz RoF LANs.