In future mobile networks, the evolution of optical transport architectures enabling the flexible, scalable interconnection of Baseband Units (BBUs) and Radio Units (RUs) with heterogeneous interfaces is a significant issue. In this paper, we propose a multi-technology hybrid transport architecture that comprises both analog and digital-Radio over Fiber (RoF) mobile network segments relying on a dynamically reconfigurable optical switching node. As a step forward, the integration of the discussed network layout into an existing mobile infrastructure is demonstrated, enabling the support of real-world services through both standard digital and Analog–Intermediate- Frequency over Fiber (A-IFoF)-based converged fiber–wireless paths. Emphasis has been placed on the implementation of a real-time A-IFoF transceiver that is employed through a single embedded fully programmable gateway array (FPGA)-based platform that serves as an Ethernet to Intermediate Frequency (IF) bridge for the transmission of legacy traffic over the analog network segment. The experimental evaluation of the proposed concept was based on the dynamic optical routing of the legacy Common Public Radio Interface (CPRI), 1.5 GBaud analog-intermediate frequency-over-fiber (A-IFoF)/mmWave and 10 Gbps binary optical waveforms, showing acceptable error vector magnitude (EVM) values for the complex radio waveforms and error-free operation for binary optical streams, with Bit Error Rate (BER) values less than 10⁻⁹. Finally, the end-to-end proof-of-concept demonstration of the proposed solution was achieved through the delivery of 4K video streaming and Internet Protocol (IP) calls over a mobile core network.

The relentless traffic growth in datacenter networks is stimulating the adoption of pioneering optical interconnect technologies as well as their integration with novel network and switching architectures. Even more, the need for disaggregation of data storage and processing resources significantly increases the capacity and dimensioning requirements of such networks. In this context, a novel datacenter network architecture that combines space and wavelength switching functionalities is demonstrated experimentally. The architecture leverages slotted TDMA/WDM switching to realize dynamic resource allocation with sub-wavelength granularity, thus realizing a low cost and power consumption, scalable datacenter network. Dynamic reconfiguration of the slotted network vouches for low latency operation of the data plane and hence, it fulfils the requirements of the envisaged disaggregated datacenter infrastructure. The current paper reports the experimental evaluation of the optical subsystems and demonstrates the proof of concept for combined space- and wavelength-switching with optical bursts of 200 μs duration in different network scenarios. The generation and reception of slotted traffic, as well as the control of the optical switching subsystems is performed by means of addressable FPGA boards.

Riding on Moore's law, established datacenter network infrastructure technologies are scaling up rapidly; however, increasing concerns are being expressed by the industry that these technologies could be outpaced in the near future by the sheer growth of the traffic and new technologies are sought. In this backdrop, optical switching is gaining momentum as a potential path for gracefully scaling datacenter networks, due to its inherent speed, energy efficiency and transparency to bitrate and protocol. European project NEPHELE is developing an optical network infrastructure that leverages optical switching within a software-defined networking (SDN) framework to overcome the bandwidth and energy scaling challenges of datacenter networks. Within this project, a vertically integrated optical datacenter network test-bed prototype was set up and its operation was demonstrated in lab environment. Different scenarios using the NEPHELE dataplane are reported, underpinning the feasibility of the proposed network architecture. Moreover, dynamic allocation of network resources is also envisaged, leveraging the slotted operation of the reported optical datacenter network. Finally, the evaluation of a Wavelength Selective Switch (WSS) based on commercial off-the-self-components is reported, scaling up to eight wavelengths and enabling optical switching in ultra-fast dynamic operation.

The NEPHELE hybrid electro-optical datacenter network (DCN) architecture is proposed as a dynamic network solution to provide high capacity, scalability, and cost efficiency in comparison to the existing DCN infrastructures. The details of the NEPHELE DCN architecture and its various key parts are introduced, and the performance of its implementation is evaluated through an end-to-end NEPHELE demonstrator, which was built at the National Technical University of Athens. Several communication scenarios are demonstrated in real time, exploiting a scalable optical data-plane architecture with a software-defined network (SDN) control plane capable of slotted operation for dynamic allocation of network resources. Real-time end-to-end functionality and integration of various software and hardware components are verified in a six-host prototype datacenter cluster.

Optical switching is gaining traction for scaling datacenter networks, apace with soaring traffic demand. We experimentally evaluate a slotted optical network architecture capable of dynamically allocating network resources with sub-wavelength granularity. Network operation is demonstrated with multiple communication scenarios, using 200 μs duration optical bursts.