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40Gb/s & 100Gb/s Transport in the WAN October 10, 2007. Daniel Bihon Fujitsu Laboratories of America, Inc. Richardson, Texas. Introduction. Today’s networks deploy 2.5Gbps and 10Gbps line rates Networks will migrate to 40Gbps (and in the future to 100Gbps) per wavelength
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40Gb/s & 100Gb/s Transport in the WANOctober 10, 2007 Daniel Bihon Fujitsu Laboratories of America, Inc. Richardson, Texas
Introduction • Today’s networks deploy 2.5Gbps and 10Gbps line rates • Networks will migrate to 40Gbps (and in the future to 100Gbps) per wavelength • High demand for transmission capacity • Higher rate client interfaces • Transmission Quality and Connectivity • Challenges associated with 40Gbps and 100Gbps solution: • OSNR requirement increases by 6dB and 10dB respectively • Chromatic dispersion tolerance decreases respectively (1/16-th and 1/100 of 10G system) • Similarly PMD tolerance decreases (1/4- and 1/10th of 10G system) • Significant increase to OADM filtering • Counter-measures • Advanced multi-level modulation formats • Low symbol rate • Tunable/Adaptive CD compensation • Forward error correction (FEC) • Coherent detection • PMD and CD tolerance can be further improved
Intensity Phase (Frequency) Polarization Light Properties to Modulate • Modulate one or more light properties • Intensity modulation (on-off keying): • Widely used modulation technique for up to 10Gbps transmission • Easy to modulate and easy to detect • Phase modulation: • Well known technique but was not used in optical communications • Detection is more difficult compared to on-off keying • Polarization modulation: • Relatively new technique • Detection is difficult
40 Gbps Modulation Formats • RZ-DQPSK is attractive in many aspects for high bit-rate transmission CS-RZ NRZ Duobinary RZ-DPSK RZ-DQPSK : Advantage Tx out Tx out MZI out MZI out : Disadvantage “1” DPhase= “0” DPhase= 0 4 values are mapped to Dphase 0, /2, , 3/2 Optical spectra Frequency (GHz) Frequency (GHz) Frequency (GHz) Frequency (GHz) Frequency (GHz) Optical noise tolerance poor medium very good very poor good medium good (in linear regime) medium medium good Chromatic dispersion tolerance poor medium PMD tolerance medium good medium Optical nonlinearity tolerance good medium poor good good medium OADM filtering tolerance good medium good medium
100+ Gbps Transmission Question: How to transport 100GE in DWDM networks? Parallel Serial • Transport on single wavelength • Complex Tx/Rx • Higher spectral efficiency • Higher total transport capacity over a WDM system • Transmission impairments • Transport on multiple wavelengths • Requires synchronization of wavelengths due to differential propagation delay • Manage a band of wavelengths • Simpler Tx/Rx, but low fiber utilization
SP- and DP-QPSK for 40 and 100G Fujitsu Laboratories is doing intensive research on SP- and DP-QPSK