The Optical Networks and Systems Laboratory (ONS Lab) is equipped with appropriate facilities and equipment for the experimental activities mainly conducted within the common framework provided by the ADRENALINE testbed ®, which is deployed in the ONS Lab and encompasses multiple interrelated although independent components and prototypes, to offer end-to-end services across a wide range of heterogeneous network and cloud technologies. The ONS Lab consists of three rooms on the main floor of CTTC B4 building:

  • Optical Transmission and Subsystems Lab (room 0.02), where the Experimental platform for Optical orthogonal frequency division multiplexing (OFDM) Systems (EOS) is deployed as a main part of ADRENALINE testbed. EOS platform integrates several optical, electro-optical and electrical devices necessary to implement different schemes of both transmitter and receiver subsystems of the sliceable bandwidth/bitrate variable transceivers (S-BVTs). In particular, for the transmission side there is a four-channel digital-to-analog converter (DAC) with up to 65 GSa/s and >13 GHz bandwidth (Fig. 1, right), a LiNbO3 Mach-Zehnder modulator (MZM) with RF driver (both up to 40 GHz) to generate the optical signal for intensity modulation (IM) schemes with direct detection (DD), another LiNbO3 MZM usable up to 40 GHz with low Vpi and ultra linear RF driver (50 GHz), a LiNbO3 phase modulator (up to 12 GHz bandwidth for constant envelope, CE, schemes), a coherent (CO) transmission front-end with nested I/Q MZM (based on GaAs, for advanced 40 Gb/s DQPSK transmission) and with ultra linear RF drivers (up to 40 GHz) as depicted in Fig. 1 (left), and a nested DP-QPSK MZM for 100 Gb/s transmission with dual polarization (DP), low Vpi (<3.5V), and with ultra linear RF drivers (up to 50 GHz). For the reception side there is an ultrafast InGaAs PIN photo-detector (50 GHz bandwidth, loaded with 50 ?, and 0.6 A/W of responsivity), a CO receiver front-end featuring phase and polarization diversities (with four pairs of waveguide-integrated photo-detectors on a single chip connected as balanced detectors, with 42 GHz bandwidth, and with a 90º optical hybrid with two single polarization), and two PIN photo-receivers with TIA in lab-buddy box (0.55 A/W of responsivity at 1550 nm, >18 GHz bandwidth).

 

Figure 1. Nested I/Q MZM with RF Drivers (left). DAC with 65 GSa/s and >13 GHz (right)

 

Other devices can be placed wherein they are needed during the transceivers implementations: RF amplifiers (24 dB of Gain, up to 20 GHz) to adapt the power of the RF signal, two athermal arrayed waveguide gratings (AWGs, with 40 Gaussian channels of 100GHz) for the transmission of multiple flows aggregated in S-BVTs and noise filtering at reception side, or a programmable single-stage EDFA Gain Block (Fig. 5, left) to provide a flattened gain spectrum at the output/input of the sliceable transmitter/receiver prototype with low Noise Figure (NF) for C-Band. Devices such as double-balanced mixers (IF up to 10 GHz, LO/RF from 9 to 20 GHz), a 2 way-0º power splitter (up to 18 GHz), and a voltage controlled oscillator (VCO, up to 20 GHz) are useful to implement RF up-conversion/down-conversion stages within the transmitter/receiver respectively.


This room is connected, from two different locations, to the racks of ADRENALINE testbed (deployed in the room 0.03, described below) by means of two underground-technical optical links, each consisting of several single-mode patch cords connected between a pair of fiber-optic patch panels (Fig. 2, right). This makes possible the experimental validation and performance evaluation of the implemented S-BVTs over the Wavelength Switched Optical Network (WSON) of ADRENALINE. The floor carpet is certificated with an electrostatic behavior of Conductive, and is grounded to drain electrostatic charges deposited on it. Some elements provide ESD protection along the different work benches. In the middle of the room there is a 2.5m x 1.5m all-steel optical table (Fig. 2, left) with a surface mechanized with M6 x 1.0 mounting holes for secure-fixing of devices/components; the four legs of this table feature closed pneumatic isolation system and passive vertical vibration isolating supports, with 22 dB of vertical transmissibility at resonance, and 74% of isolation efficiency at 10 Hz. Besides the vibration isolation, the optical table provides secure-fixing of devices/components and a good thermal conductivity.

 

Figure 2. Room 0.02 with optical table (left). Fiber-optic patch panel on the optical table shelf (right)

 

  • Optical Networking and Systems Lab Operations Center (room 0.03), where all the racks of the ADRENALINE testbed are placed. These racks (Fig. 3) contain the different high-performance servers, OpenFlow/Ethernet switches, Software Defined Networking (SDN) controllers, Generalized Multiprotocol Label Switching (GMPLS) controllers, Cloud controllers, Network Function Virtualization (NFV) orchestrators, four optical nodes (ROADM/OXC) with five bidirectional optical links (with lengths ranging from 35 to 150 Km) for the WSON, and further equipment necessary to deploy the heterogeneous networks and technologies (e.g, connection-oriented IP/Ethernet Packet Transport Network, fixed/flexi-grid DWDM Metro/Core Network, Computing Datacenters) that are combined in order to deploy, in a flexible manner, the other main demonstration platform within the framework of the ADRENALINE testbed:  SDN/NFV Cloud Computing Platform and Core Network for 5G Services, that encompasses multiple interrelated although independent components and prototypes, to offer end-to-end services.

 


 
Figure 3. Room 0.03 with racks of ADRENALINE testbed®


This is the main room of the ONS lab, having underground-technical optical links with the above described room (0.02), and also with the last room of the ONS Lab, described below:

  •  Optical Network Control and Service Management Lab (room 0.04), where all the computers intended for the control and management of the SDN/NFV Cloud Computing Platform and Core Network for 5G Services of the ADRENALINE testbed are placed. Among others, applications for testbed operation can be found, such as ADRENALINE Network Configurator (ADNETCONF) and ADRENALINE Network Generator (ADNETGEN). These advanced and adapted software applications and tools allow the rapid operation and maintenance of the testbed, including common tasks such as the configuration and parameterization of the network topology, the generation of client requests modelling the behavior of network customers, or the monitoring, data-mining and statistical processing of obtained results, allowing researchers to obtain numerical performance data and to perform experimental research and quantitative comparative analysis.

Moreover, this room contains the Edge nodes for the interconnection with other CTTC testbed facilities providing the wireless HetNet and backhaul (EXTREME Testbed® and LENA LTE-EPC protocol stack emulator) and wireless sensors networks (IoTWorld Testbed®).


This room is also connected to the racks of ADRENALINE testbed (installed in the room 0.03) by means of two underground-technical optical links, with several multi-mode and several single-mode patch cords connected between fiber-optic patch panels. The floor of this room is also certified as Conductive and connected to ground. Thereby, it is possible to perform hardware maintenance and upgrades on the equipment (e.g., servers, switches) of ADRENALINE testbed in a safe way.

Physical layer degradations can be modelled, measured and quantified with optical communication test and measurement equipment also available in the ONS Lab (Fig. 4), such as a communications signal analyzer (up to 20 GSa/s, with 4 GHz bandwidth, provided with optical and electrical inputs), a digital sampling oscilloscope (up to 13.5 Gb/s with 9 GHz optical/20 GHz electrical sampling module), an optical spectrum analyzer (with DWDM analysis, for a wavelength range between 600 and 1750 nm), various tunable laser sources with several slots (covering S+C+L bands, some of them with low linewidth <100 KHz, providing up to 13 dBm output power), a dual wavelength laser light source (of 1310 and/or 1550 nm), a portable optical time-domain reflectometer (OTDR, with two wavelengths of 1310 nm and 1550 nm), a high-performance optical multimeter (with variable optical attenuator and high power sensor modules), some optical power meters (for 850, 1300, 1310, 1490, and 1550 nm), a polarization scrambler, polarization mode dispersion (PMD, using the interferometric method) and chromatic dispersion (CD, using phase-shift method) analyzers, a broadband source (C and L bands, useful as a PMD/CD analyzer source), and a fixed PMD emulator (1, 5 and 10 ps). The can be used during performance evaluation of S-BVTs implemented in the room 0.02 in back-to-back configuration, or after crossing some fiber-optic spools that can be attached to them. Moreover, physical degradations accumulated along the WSON of ADRENALINE (deployed in room 0.03) can be analyzed and quantified during the experiments that involve the S-BVTs connected to the optical Metro/Core network.

 


 
Figure 4. Optical communication test and measurement equipment



Belonging to this category, there is additional equipment (i.e., instrumentation and high-performance computation) in the ONS Lab intended for the development of the EOS platform of ADRENALINE: on the one hand, an arbitrary waveform generator (up to 24 GSa/s, 9.6 GHz effective RF frequency output, and 7.5 GHz analog bandwidth) provides one or two analog signals in parallel (from digital ones) that will be later modulated to the optical domain; on the other hand, the received signal converted to the electrical domain is captured, sampled and post-processed by a real-time digital phosphor oscilloscope (up to 100 GSa/s, 20 GHz bandwidth). Off-line DSP at transmitter/receiver is performed by software codes (e.g. Matlab or Python) running on 2xIntel Xeon E5-2603 Quad-64GB platform, which is connected to the instruments through TCP/IP sockets. Two bench-top Erbium-doped fiber amplifiers (EDFAs) for DWDM multichannel (covering C-band, with output power up to +23 dBm and nominal Gain of 30 dB) are available for amplification at transmitter/receiver sides, and two programmable optical filters based on high resolution liquid crystal on Silicon technology (LCoS, with arbitrary filter shape, control of filter dispersion, and filter bandwidth variable from 10 GHz to 5 THz, covering C+L bands) can be placed in the transmitter/receiver for the configuration of flexi-grid links. One of those filters is provided with 1x4 ports, being usable as a wavelength selective switch (WSS) in order to aggregate/distribute multiple flows.


Design, development and assembly of hardware for new opto-electronic subsystems (Fig. 5, right) is possible thanks to several facilities and equipment, such as, printed circuit board (PCB) designer software (for schematics and layouts, including integration with manufacturing output tools), FPGA simulation and synthesis software, dual (up to 20V) and triple (up to 30V, with tracking function) DC Power supplies, a DC+AC RMS multimeter (able to perform frequency, capacitance, duty cycle and pulse width measurements), a portable oscilloscope with 2 passive probes (150 MHz), a soldering station and other devices (e.g., ARDUINO, Raspberry Pi or UNC20 kits).
      

Figure 5. PreAmp/Booster EDFA module (left). Developed and assembled prototype for ADRENALINE Testbed® (right)


Optical passive components and fiber-optic inspection devices are suitable for making measurements and experiments that involve the use of test and measurement equipment over the two main platforms of ADRENALINE: a mini video microscope with camera and TFT display can be found, also a precision fiber cleaver (for fibers between 80 and 200 µm), or several fiber-optic adapters (simplex and duplex, for different kinds of connectors), attenuators (different kinds, from 1 to 15 dB), several fiber-optic patch cords (1,2, 3, 5 or 10 m, also terminated with different kinds of connectors), different 1x2 SM optical couplers (ratio equal to 50/50, 10/90 or 5/95), two 45º Faraday rotators (in-line, from PMF to PMF), four Polarization Controllers (PC), two optical circulators of three ports, and two Polarization Beam Splitters/Combiners (PBS/PBC). Furthermore, several standard G652 SM fiber-optic spools are available (1, 2, 5, 10, 25 and 50 Km, all with 0.19 dB/Km of attenuation), in order to evaluate the transmission over different distances. In the same way, several RF Components are also available: 50? cable assemblies with different lengths (up to 1.5 m), material characteristics (hand-formable, semi-rigid or flexible), frequency range (from DC to 12.4, 13, 18, 26, 26.5, 40 and 65 GHz), and with different terminations (SMA, SMP, V, GPPO, etc.). There are also several RF adapters (SMA, V or K interfaces) up to 40 GHz, RF attenuators (from 3 to 20 dB, with frequency range either up to 18 GHz or up to 26 GHz), loads (50 ?), DC-blocks and different low-pass filters (from DC to either 5 GHz or 7.2 GHz). Additionally, test and measurement cables (red and black with different terminations) can be used for providing electrical connections throughout the experiments.


Software applications are designed and developed on the requirements of researchers. The ONS department has strong knowledge of C/C++ (C99 / c++11), including standard, Boost and Qt libraries, proved by the expertise in developing GNU/Linux system and applications. Software development team also uses Perl, Python and Java. The servers include all necessary services for software development: bugtracking, version control (subversion), Fully Automated Linux, drupal and phpBB for web-based services. Several development methodologies have been successfully applied, such as Waterfall, V-Model or Agile.

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