Fujitsu Network Communications has integrated 40 Gbps transmission capabilities into its FLASHWAVE 7500 Reconfigurable Optical Add/Drop Multiplexer (ROADM), enabling 10-Gbps metro DWDM networks based on the platform to grow from 400 Gbps to 1.6 Tbps of total capacity.
Fujitsu has developed an advanced modulation scheme and per-wavelength variable dispersion compensation (VDC) to support the 40 Gbps rate. Optical performance requirements such as optical signal-to-noise ratio (OSNR), chromatic dispersion, polarization mode dispersion (PMD), and spectral width become much more stringent as bit rates increase.
Fujitsu said that by utilizing a Return to Zero Differential Quadrature Phase Shift Keying (RZ-DQPSK) modulation scheme and per-transponder VDC, there is no need to change dispersion compensation of existing networks when upgrading to support 40 Gbps wavelengths. These technologies significantly improve PMD tolerance and OSNR performance of DWDM networks, resulting in longer spans, fewer regeneration sites, and increased number of ROADM nodes per network.
Three new 40 Gbps units for the FLASHWAVE 7500 ROADM offer options for multiple deployment scenarios. The 40 Gbps transponder provides a full band tunable network interface and a 40 Gbps client interface, designed primarily for interconnection of core routers. The 40 Gbps muxponder combines four 10 Gbps client interfaces into a single wavelength operating at 40 Gbps, which provides additional capacity expansion on constrained routes. The 40 Gbps regenerator unit eliminates back-to-back transponders on long spans, reducing cost and complexity. Each unit plugs directly into the existing FLASHWAVE 7500 chassis with no changes required to support 40 Gbps wavelengths across existing metro/regional DWDM networks.
"While many of our potential competitors have chosen a 40 Gbps solution that requires an external shelf and alien wavelengths to work, we believe that our fully-integrated approach offers a far more compelling and manageable option for carriers. By integrating 40 Gbps capability directly into the ROADM, we will achieve greater distance performance, while simplifying operations with fewer fiber jumpers, better performance monitoring, fewer spares, and an overall reduction in space and power," said Bill Erickson, senior vice president of planning and development at Fujitsu Network Communications.
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- Fujitsu's FLASHWAVE 7500 ROADM is widely deployed in the RBOC and MSO markets for core network consolidation, metro/regional capacity relief, and triple-play service delivery. It uses a Wavelength Selective Switch (WSS) architecture to add, drop or pass-though up to 40 channels at any node with single channel granularity.
