MAY 12, 2008 By Meghan Fuller Hanna -- OpVista (search for OpVista) today announced its new Dense Multi-Carrier (DMC) technology which it claims enables it to support 40G and100G transmission per wavelength over existing 10-Gbit/sec networks. The vendor says the DMC technology enables it to deliver fiber capacity up to 8 Tbit/sec over today's 10-Gbit/sec-engineered networks.
The DMC technology is included in the company's forthcoming CX8 optical networking system, which is slated for general availability in 4Q 2008. The company says its 40G transponder will be available in the second half of this year, while the 100G transponder is expected late this year or early next year.
Zahir Addetia, vice president of product line marketing and strategy at OpVista says that the DMC technology answers a key question: How do you make use of the existing network and components and also enhance the scalability of the existing network? To reengineer the network for 40-Gbit/sec transmission and beyond is cost prohibitive for many carriers.
"If you were to go through a traditional network build using some of the conventional 40- and 100-Gbit technologies, you'd need to reengineer the plants, touch everything from your dispersion compensation to your ROADMs to your amplification," says Addetia. "In fact, what you are really doing is building a new fiber plant. Before you even get to the transponders, you have this outlay cost where you have to rebuild the network."
OpVista's DMC technology, by contrast, enables operators to transmit 40-Gbit/sec traffic over their existing 10G networks. Based on a combination of multiple carrier photonics, wavelength stabilization, and multi-level modulation, OpVista's DMC technology allows operators to use multiple carriers within a single ITU window.
As a result, its 40G technology--and forthcoming 100G technology--obeys all the 10G engineering rules. Currently available advanced modulation schemes like DPSK, DQPSK, and duo-binary require additional dispersion compensation to mitigate the effects of polarization mode dispersion (PMD) and chromatic dispersion inherent in higher data rate transmission, notes Addetia. But because OpVista's DMC technology runs over 10G networks, operators will not need to change their dispersion compensation or worry about their existing amplifiers or ROADMs; the DMC technology enables carriers to preserve their existing optical backbone.
"If I had an existing fiber plant, I can start populating my 40- and 100-Gig transponders as needed," explains Addetia. "It's pay-as-you-grow; you add transponders to the network." In short, he says, the DMC technology enables operators to "harvest the bandwidth" on their existing 10-Gig networks.
"Despite growing carrier demand for 40G network upgrades, these upgrades have been limited to date by supply chain constraints and unfavorable economics relative to 10G upgrades," adds Dana Cooperson, vice president of network infrastructure at Ovum. "OpVista's 40G DMC technology, which is based on mature 10G components and a novel combination of analog and digital design techniques, could expand the 40G market beyond our five-year forecast of 70% CAGR by lowering the 40G cost curve and increasing the range of addressable upgrade applications faster than we expected."
Addetia also cites the improved fiber capacity versus spectral efficiency afforded by the company's DMC technology as a key benefit. Today, operators typically support 10 Gbits/sec over 100-GHz channel spacing or 10 Gbits/sec over 50-GHz channel spacing, for a spectral density of 0.1 and 0.2 respectively. "The [40G] solution we have coming out later this year will give you a spectral density of 0.4 or 40 Gig per ITU window," he reports. "And the [100G] solution we have coming out in Q2 of next year is 100 Gig within 100 GHz, so that gives you a spectral density of 1.0."
Addetia confirms that the DMC technology can also be added to the installed base of OpVista2000 optical transport systems. "We are planning to support the same 40-Gig card that's going to be in our CX8," he says. "It's a two-slot card that you can add to an existing system; it's very straightforward."
Several years ago, OpVista announced a similar technology which would enable an operator to support 10-Gbit/sec transmission over a 2.5-Gbit/sec network. So what about its existing customers who are already running 10G over 2.5G? OpVista says it has an upgrade strategy for them too. In fact, the vendor says it recently conducted a trial with one such customer whose network features a 2.5-Gbit/sec fiber plant and amplification at all the correct distances. But the network did not have any dispersion compensation. "In that case," says Addetia, "what we would have to do is just add the dispersion compensation at the sites where they have amplifiers. Then they would be able to continue using the existing 10-Gig on 2.5 [Gig] that they have and be able to add 40G on those particular networks too."
To enable 100-Gbit/sec transmission--which OpVista hopes to unveil late this year--the company increases the data rate and adds an additional wavelength. The vendor says it uses a higher order modulation rate to enable it to carry more information within the same symbols. "What we have is five carriers carrying 20 Gbits of information, but it's 10-Gig symbols per second," he explains. "You are still running at 10 Gig. If I put it on my existing network, I'm still using my 10-Gig engineering rules, and that's how we avoid PMD and Chromatic Dispersion issues. That's the key to the optical performance."
Addetia says OpVista will showcase the optical performance of its 100-Gbit/sec capabilities over a 10-Gbit/sec network next month at the NXTComm08 Conference in Las Vegas. "What we are planning to demonstrate is that you can have 10-Gig signals carried together with some of the 100 Gig using our technology. This becomes very challenging as you go toward DQPSK, DPSK, and duo-binary," he says.