Optical Transport Systems for Next-generation Networks

INTRODUCTION OPTICAL transport technology has mainly been used for transport systems for long-haul transmission of large volumes of data between cities. As a consequence of the continuing conversion of network broadband access, however, optical transport technology is beginning to be applied to transmission within cities and to access systems for users. Optical access systems that perform optical transmission by optical fiber from homes and businesses enable high-speed access faster than ADSL (asymmetric digital subscriber line) and cable modems; therefore, they are considered the ultimate method for broadband access. As IP (Internet Protocol) conversion of network OVERVIEW: For the transition from existing networks to NGNs, development is continuing in respect to two main pillars: the transport stratum and the service stratum. As for the transport stratum, though both IP networks and optical networks are involved, in the present article, products for optical transport systems only are discussed. In regards to providing a comfortable broadband network environment, optical transport technology plays an important role in whatever network concerned, namely, the core network, metro network, or access network. Hitachi is providing various kinds of optical transport systems aimed at each of these network domains. As for a system in the core network for constructing a large-capacity Ethernet* network, the optical transport platform AMN7500—on which an optical cross-connect network or a ROADM can be constructed—is being provided. By using WDM technology, it is possible to set up an easy-to-use, convenient optical core network that can be flexibly reconfigured. Moreover, for construction of a metro network for easily handing large volumes of data, a CWDM system is suitable. Using this system, network providers can construct the most suitable system to meet their service requirements.