17 September 2012

ClariPhy boosts 40G LightSpeed coherent SoC to 47Gbps to support FEC in Cortina’s OTN processors for metro and regional networks

ClariPhy Communications Inc of Irvine, CA, a fabless developer of mixed-signal digital signal processing (MXSP) system-on-chip (SoC) ICs for coherent optical networks, has announced an optimized 40G coherent SoC for metro networks.

The advantages of dual-polarization QPSK (DP-QPSK) coherent technology – simplicity of deployment, dramatically increased fiber reach and capacity, and lower total cost of ownership – are well established in long-haul and submarine networks, and have been the key drivers for significant global deployment of ClariPhy’s coherent solutions. Operators are now seeking to leverage these benefits in cost-efficient and scalable metro and regional networks, adds the firm. This requires a solution immune to cross phase modulation (XPM), which results from the interference of adjacent 10G channels onto 40G DP-QPSK wavelengths in a dense wavelength division multiplexing (DWDM) system and which limits the number of optical spans and reach achievable in metro coherent deployments.

ClariPhy has collaborated with optical transport network (OTN) solution provider Cortina Systems Inc of Sunnyvale, CA to solve the XPM problem and enable 40G coherent deployments in metro and regional networks. The solution comprises ClariPhy’s CL4010 LightSpeed Coherent SoC, operating at an increased data rate of 47Gbps to support the advanced forward error correction (FEC) capabilities available in Cortina’s CS604x and CS600x OTN processors. The combined solution improves optical signal-to-noise ratio (OSNR) sensitivity by up to 3dB. This, combined with the inherent capability of coherent transmission to deal with the polarization mode dispersion (PMD) present in legacy metro networks, increases the number of network spans and total reach by 50%. Carriers can now cost-effectively enable network links with up to 15 spans and at least 1200km reach, says ClariPhy. The solution also enables deployment of adjacent 40G and 10G wavelengths, without guard banding, allowing operators to maximize fiber capacity and reduce cost per bit.

The increased data rate of 47Gbps supports powerful FEC with a 13% overhead transporting four 10G Ethernet clients mapped into a standard ODU3e1 or ODU3e2 payload. If desired, even more powerful FEC schemes can be employed using Cortina’s 20%- and 25%-overhead FEC codes. These codes can be used with ClariPhy’s CL5018 LightSpeed Coherent SoC, which supports data rates of 47-50Gbps.

ClariPhy and Cortina says that they worked with a leading provider of metropolitan networking equipment to test the solution. The results are reported in the paper ‘Use of High Gain FEC to Counteract XPM in Metro Networks Combining 40G Coherent DP-QPSK and 10G OOK Channels’ being presented at the IEEE Photonics Conference 2012 in Burlingame, CA, USA on 26 September.

ClariPhy’s CL4010 LightSpeed Coherent SoC has been shipping since 2011 and is currently available in multi-source agreement (MSA) modules from partners such as Oclaro, NEC and JDSU. Cortina’s 40G OTN processors have already been integrated into OEMs’ metro platforms worldwide. Modules with ClariPhy’s enhanced 47Gbps CL4010 will sample in September, enabling OEMs and network operators to benefit from the synergies and economies of scale of a common coherent solution in long-haul, submarine and metro optical transport networks.

“Solving the cross-phase modulation was critical to adoption of coherent technology in metro networks,” comments Cortina VP Arun Zarabi. “By working closely with ClariPhy to remove this significant barrier, we were able to fine tune the XPM-tolerant 47G coherent solution, thus enabling system manufacturers the ability to maximize fiber capacity and reduce cost per bit,” he adds. 

“The higher-bit-rate capability of the enhanced LightSpeed SoC from ClariPhy will help our customers to deploy 40G coherent line-cards more widely in metro networks, which are already carrying intensity-modulated wavelengths such as conventional 10G connections,” says Richard Smart, Oclaro’s senior VP & general manager of Optical Network Subsystems. “This feature enables network operators to introduce coherent technology more pervasively without having to build overlay networks,” he adds.

“We are pleased to have removed the main obstacle facing operators in deploying 40G coherent over brownfield networks, where existing 10G traffic can interfere with 40G wavelengths,” says ClariPhy’s chief technology officer Norm Swenson. “Our strong ecosystem of module partners has allowed us to ship more coherent SoCs than all other merchant silicon suppliers combined,” he claims. “We are now in a strong position to address the high-volume metro market with a cost-effective and smooth upgrade to 40G coherent technology.”

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