tailieunhanh - Optical Networks: A Practical Perspective - Part 65

Optical Networks: A Practical Perspective - Part 65. This book describes a revolution within a revolution, the opening up of the capacity of the now-familiar optical fiber to carry more messages, handle a wider variety of transmission types, and provide improved reliabilities and ease of use. In many places where fiber has been installed simply as a better form of copper, even the gigabit capacities that result have not proved adequate to keep up with the demand. The inborn human voracity for more and more bandwidth, plus the growing realization that there are other flexibilities to be had by imaginative use of the fiber, have led people. | 610 Access Networks bandwidth. Moreover this wavelength-routed PON can also support broadcast services efficiently using the spectral slicing technique described earlier. Thus there is an upgrade path starting from a broadcast network with shared bandwidth to a broadcast network with dedicated bandwidth and eventually to a switched network with dedicated bandwidth. Summary Service providers both telephone operators and cable companies are actively looking to deploy broadband access networks to provide a variety of new services. Fiber-based services are now available for many businesses in metropolitan areas. When it comes to residential access however fiber is yet to reach the home. SONET SDH ring-based architectures have been deployed to support the needs of large business customers but they are not as suited for supporting the needs of residential users and small business customers. The two main architectures for broadband access networks are the hybrid fiber coax HFC architecture which is based on evolving the current plant deployed by cable television operators and the fiber to the curb FTTC architecture or equivalently a passive optical network PON architecture. Compared to the HFC approach FTTC has a higher initial cost but provides bandwidth deeper in the network and may prove to be a better longer-term solution. Although FTTC refers to a simple broadcast TDM star PON architecture we also explored several upgrade options of the PON approach that provide higher capacities by making clever use of wavelength division multiplexing techniques. A number of major telephone carriers and manufacturers in the world have gotten together and defined the requirements for an FTTC-based architecture to enable them to deploy the full service access network FSA98 . As of this writing PONs based on this architecture are just beginning to be deployed. FTTC is attractive in places where coaxial cable is not already deployed which is the case in many countries other than the .

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