Optical Alphabet Soup

Do you know the difference between DQPSK, DPQPSK, and DPSK?

November 16, 2007

1 Min Read
Optical Alphabet Soup

6:30 PM -- One of the more interesting findings of Heavy Reading's latest report is the fact that a vast majority of service providers have no idea which modulation scheme is best for new 40-Gbit/s and 100-Gbit/s networks. (See The Road to 100G Winds Up Carriers and Optical's Great Leap Forward.)

According to a survey of 105 service providers, which is in the report entitled The Future of Optical Transport Networks: 40G & the Road to 100G, more than 70 percent do not know or are unsure which modulation scheme they should use when deploying higher-capacity networks.


"Based on this research, there's not a tremendous amount of knowledge out there about which modulation scheme is best," says Heavy Reading analyst Sterling Perrin. "Everyone is trying out a different approach, so it will be a challenge for suppliers to convince operators that their solution is the best."

Part of the problem, Perrin says, is that all of the abbreviations for these different modulations schemes look the same -- DQPSK, DPQPSK, DPSK, partial DPSK, etc.

It's what he calls a modulation alphabet soup, which is just serving to confuse the market further.

This becomes problematic as service providers look to deploy 40-Gig technology, because some are doing so with an eye to using the same technology for 100 Gig.

"If you buy into someone's 40-gig equipment you'd probably want to go with them for 100-gig, which is probably the way operators will want to do it," Perrin says.

But how can you bet on a modulation scheme if you aren't sure it's what's best? Or even what the acronym stands for?

— Ryan Lawler, Reporter, Light Reading

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