By Stephen Hardy, Lightwave -- AT&T has seen this week's Verizon 100-Gbps trial and raised it 27 Gbps with a trial of live traffic at 127 Gbps. The extra 27 Gbps represents the overhead necessary for forward error correction (FEC). The carrier conducted the trial using modem optics and 100GBase-LR4 CFP optical modules from Opnext and the CRS-3 Carrier Routing System Cisco, announced this week.
Ixia’s “K2” 100-Gbps traffic generator and analyzer also was used in the trial.
The trial link ran for more than 900 miles and connected a site in Florida with New Orleans. According to Ed Cornejo, vice president of product marketing at Opnext, the trial used dual polarization quadrature phase-shift keying (DP-QPSK) with coherent detection, housed in what Cornejo described as a demonstration “shelf.” The demonstrator, which leverages the 40-Gbps OTS-4000 subsystem originally developed by StrataLight Communications before Opnext acquired the company, not only enables carriers to trial 100-Gbps links with and additional 20% overhead for FEC, but offers Opnext the chance to test the performance of its coherent receiver electronics and algorithms developed especially for the 100-Gbps market. Cornejo says the company was pleased with the performance of the demonstrator during the trials.
Cornejo added that the trials included an examination of 127-Gbps transmission alongside adjacent 40-Gbps traffic. Again, this aspect of the trials went well, Cornejo reports.
The trial marked the first field testing of optical technology that can accommodate 20% FEC overhead, Cornejo asserted. Most other trials have supported approximately 7%, he believes.
The test impressed at least one analyst. “Most of the 100G coherent trials announced in the past are not real time solutions and are only testing the optics; the data is acquired on a digitizing oscilloscope and coherent DSP post-processing is offloaded to a PC,” said Andrew Schmitt, directing analyst of optical at Infonetics Research. “Opnext's trial is different because they are demonstrating a real-time solution implemented in hardware for the toughest part of the 100G coherent transport problem.”
Cornejo revealed that his company has a full slate of carrier field trials booked for this year. At least one includes a trial of 40-Gbps coherent technology for submarine applications. He says that carriers hope to see commercial products that leverage technology such as Opnext demonstrated in early 2011, with significant deployments following in 2012.