Although optical backbones will not benefit from significant investments in the next few years, they will be responsible for transporting packet-based traffic coming from massive broadband access deployments, third-generation mobile networking, and new sets of entertainment, messaging, and location-based services .
In the last couple of years, optical backbone equipment development has focused on three basic lines: enhanced DWDM, long-haul capabilities, and optical switching. Manufacturers' enhanced DWDM systems reached the point where they could populate fiber with more than 300 wavelengths at 10 Gbps. At the same time, substantial effort was spent in ultra-long-haul capabilities, enabling greater distances without electrical regeneration (>3000 km). Further breakthroughs in this area include using nonlinear transmission and the introduction of 40-Gbps channels . However, while these developments are feats of technical brilliance, market requirements are still favoring fewer channels at better prices with predictable performance characteristics .
Long-haul DWDM is one type of equipment for which there has been some traction. From an economic viewpoint, it allows substantial savings on regeneration requirements, enabling, from an architectural viewpoint, the creation of a long-reach express layer in the network, which has been adopted by some carriers .
Most of the installed base of SONET/SDH equipment has also not been replaced in the ...