MARCH 23, 2009 -- Enabling a tenfold increase in system capacity over existing metro DWDM systems utilizing traditional techniques, ADVA Optical Networking (search Lightwave for ADVA) claims it has developed a novel DPSK-3ASK (differential phase-shift keying, three-level amplitude-shift keying) modulation format for serial 100-Gbps transmission over a single wavelength channel.
In its labs in Meiningen, Germany, ADVA says its engineers successfully demonstrated for the first time this new modulation scheme, which utilizes available 40G components and facilitates operation on a standard ITU channel grid.
Operators are striving to increase the capacity of their DWDM networks and have been steadily migrating from 10G to 40G, with 100G being the next logical step.
Existing serial 100-Gbps proposals such as DP-QPSK (dual-polarization quadrature phase-shift keying) have been optimized for (ultra-)long-haul transmission. Their complexity, cost, and power consumption make them less suitable for metro applications. Given the challenge of achieving reasonable link distances at 100 Gbps due to chromatic dispersion and polarization mode dispersion, most industry work on short distances to date has centered on multifiber and multilambda approaches. Standards bodies IEEE, ITU-T, and OIF have all been working on 100-Gbps standards, with the focus currently placed on the two extremes of transmission distance.
"Current industry standardization efforts have left a gap between 40 km and 600 km, which leaves a sizeable portion of the market unaddressed. Our solution targets exactly that sweet spot," states Christoph Glingener, CTO for ADVA Optical Networking. "In addition, this solution utilizes off-the-shelf componentry, which enables it to be implemented sooner and with minimal industry investment, lessening the burden on optical component companies in a difficult market environment."
ADVA says its DPSK-3ASK technology is complementary to existing 10G and 40G designs and fits in existing installed network architectures, making it easier to upgrade and operate. Its direct detection reportedly alleviates the need for power-consuming, high-speed digital signal processing as typically required for long-haul schemes. It is compatible with DWDM systems like the ADVA FSP 3000 and, when coupled with optical amplification, facilitates metro/regional transmission distances up to 600 km.
"Lowering the cost per bit is a common theme in both metro and long-haul DWDM networks," says Glingener. "We have an extremely compact and power-efficient 40-Gbps solution today. Now, many network operators have asked us to address the metro challenge with a customized 100-Gbps solution, which is what we've done. This DPSK-3ASK demonstration is an important milestone in the industry's journey to realize 100 Gbps."
The work was partially funded by the German Ministry of Education and Research (BMBF) and is part of the CELTIC 100GET-METRO project.
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