Optical Networks emerging technologies and architectures Faculty of Computer Science, Electronics and Telecommunications Department of Telecommunications Artur Lasoń
100 Gb/s PM-QPSK (DP-QPSK) module Hot pluggable industry standard CFP2 form factor The module supports spectral shaping and multiple formats: 100G DP-QPSK (Dual Polarization) 150G DP-8QAM 200G DP-16QAM Full C-band tunable Tx and Rx, with optional Flexgrid support Maximum distance 2000 km Power dissipation <13.0W Finisair CXP 150GB Module Cisco CPAK 100GBASE-LR Module Cisco QSFP 100GBASE-LR Module
IEEE P802.3bs 400 Gbps Ethernet Task Force Done: December 2017 Link layer data rate of 400 Gbps, BER better than or equal to 10-13 8 lanes (ls) each 50 Gbps signaling rate, 4PAM modulation format (50 Gbps 4PAM suggested as backplane standard) Provide appropriate support for OTN Supports link distances of: 4PAM At least 100 m over MMF At least 10 km over SMF Wavelength lanes range from 1270-1310 nm Optical Networks (TI), Artur Lasoń
400G Ethernet optical interfaces 4l WDM - SMF 8l WDM - SMF
400G Ethernet optical interfaces OSFP CFP8 QSFP
Long haul optical networks We do not see any significant substitute or replacement technologies in our forecast timeframe for WDM equipment. However, we consider distributed computing, analytics, machine learning, AI, and SDN to contribute to overall optical network utilization and efficiency. Disaggregation and open optical networking will provide alternative and potentially lower cost vehicles for delivering WDM solutions. IHS Markit Report, 1 March 2018
Long haul application coherent detection ( ) The past year (2012) has seen remarkable growth in the deployment of coherent 100G DWDM systems, with about 10,000 total ports shipped into the core optical network. Lighwaveonline.com March 2015: World s longest terrestrial optical network route (3,998 km without regeneration) capable of 8Tbps (Facebook) transimpedance amplifiers tunable lasers with low phase noise
Polarization multiplexing (optical MIMO) The problem of polarization-mode dispersion in optical fiber transmission can be compared to the multi-path propagation in wireless communication systems. MIMO technology and algorithms proposed for space multiplexed channels in wireless systems can be used for polarization multiplexed optical channels. Optical receiver has to implement coherent detection and has to use powerful DSP engines.
100 (112) Gb/s PM-QPSK transmiter Combination of polarization multiplexing and QPSK modulation allows for symbol rate reduction by 4, at the same time we have to design transceiver with number of modulators/demodulators increased by 4.
100 (112) Gb/s PM-QPSK receiver Due to environment variations, the polarization of lightwave in fiber generally drifts with the time. The rate of this polarization drift is generally much slower than the transmission data rate. Fiber impairments can be equalized with DSP. received signal Coherent detection (homodyne, intradyne) local oscillator Coherent optical communication using polarization multiple-input-multiple-output Yan Han and Guifang Li (2005) transimpedance amplifier
CFP ACO vs CFP DCO CFP2-DCO
Photonic Crystal Fibers Silica glass fibers are limited by Rayleigh scattering ~ 0,2 db/km Nonlinear effects in silica glass limit power of the transmitted signal Commercial application of PCF in data communications is still not reasonable Index guiding fiber Photonic bandgap fiber
Few Mode Fibers MIMO technology in optical fiber uncoupled mode-division multiplexing L max FMF ~ 1000 km Six spatial modes have been used in demonstrated FMF transmission (170 km) B max of FMF proved at 73,7 Tbit/s
DWDM granularity problem CAPEX, OPEX Green networking = no traffic aggregation in electrical domain
Alien Wavelength Alien Wavelength AW just a simple concept of connecting some end-user signal directly to the DWDM system There are several advantages of AW: low cost of interconnection (no transponder needed), possible mixed line rate system, possibly different modulation format used Some disadvantages were identified as well: complex link engineering (dispersion compensation, non-linear effects), failure detection, QoS (QoT) monitoring
Elastic Optical Network DWDM is based on fixed wavelength plan (grid). All channels are used (typically) to transmit flows of the same data rate. Ethernet interfaces evolve quickly towards high speed standards 40G/100G What is preferred data rate of a single DWDM channel? Shall we keep 10 Gbps DWDM channel and use 4 channels for transport of single 40 Gbps Ethernet interface? Shall we upgrade single DWDM channel to 40/100 Gbps rate and provide grooming for all lower rate flows? We need to transport all data rates streams 100Mbps, 1Gbps, 10Gbps, 40Gbps, 100Gbps and beyond. We need elastic bandwidth plan flex grid. We need elastic optical network.
6,25 GHz DWDM vs EON Fixed spectrum allocated per channel Single carrier per channel 100 GHz
Plain Old RWA problem 50, 100 GHz slots Optical path routing Wavelength continuity (assignment) problem All possible options are acceptable regular RWA problem is to route and allocate single optical carrier (lambda)
Routing and Spectrum Allocation problem g 1 = 2/3 g 2 = 3/4 6,25 or 12,5 GHz frequency slots g 0 = 2/3 g 1 = 2/3 g 2 = 3/4 g 0 = 0 g 1 = 1/2 g 2 = 1/2 Optical path routing as in DWDM networks Spectrum continuity and contiguity (three neighboring slots) Slot allocation algorithm should take into consideration link (network) fragmentation ratio g g = 1 - (1 / frequency blocks)
Routing and Spectrum Allocation problem Main & alternate routes (paths) analysis: S1 and S2 have the same fragmentation ratio g selection of S1 results in orphan slot between two blocks selection of S1 blocks one of the potential optical path selection of S2 splits graph to two disjoint subnetworks
Bandwidth Variable Transponder BVT can be used to transmit 10 Gbps or 1 Tbps Solution 1: Full spectrum BVT highly flexible, simple but inefficient implementation of EON Solution 2: Virtual (sliceable) transponders multiplexed into single optical band
BVT Technology Photonic integrated circuits PIC use light rather than electrons to perform a wide variety of optical functions. Recent developments in nanostructures, materials, and silicon technologies have expanded the range of possible functionalities for these highly integrated optical chips Berkeley.edu
Commercial PIC based products The Infinera Infinite Capacity Engine is ( ), delivering the next step function in transport networking performance. ( ) The Infinera Infinite Capacity Engine is the first in the industry to offer network operators the combined benefits of delivering optical superchannel capacity up to 2.4 terabits per second and reach up to 12,000 kilometers in one of the world s smallest optical subsystems with very low power consumption BV-ROADM.?
Flexible modulation format/level Routing, modulation level and spectrum allocation (RMLSA) problem
(Optical) SDN Network Application Layer: This layer covers an array of applications focusing on network services, and they are mainly software applications communicating with the control layer Control Layer: As the core of SDN, the control layer consists of a centralized controller, which logically maintains a global and dynamic network view, takes requests from the application layer, and manages the network devices via standard protocols. Data-plane Layer: Infrastructure including switches, routers and network appliances. In SDN context, these devices are programmable and support standard interfaces Yong Li, Min Chen, Software-Defined Network Function Virtualization: A Survey
(Optical) SDN Network Data Flow: Source node #5 Destination S-D Light path setup. Data Flow Source - Destination
Optical SDN Network (SDN controlled EON) SDN controller -> optical node -> BVT (port, data rate, modulation, Freq slots)
Optical SDN Network (SDN controlled EON) SDN controller is responsible for right setup of all transit BV-ROADMs
Summary Great effort in high data rate optical interfaces (1Tbps) More photonic integrated circuits in commercial offer Flexible optical network (EON) Control plane for optical infrastructure (optical SDN)