Chapter 11 - Access Networks

Abstract

The access network is the “last leg” of the telecommunications network, which runs from the service provider's facility to the home or business. With fiber, now directly available to many office buildings in metropolitan areas, networks based on SONET/SDH or Ethernet-based technologies are being used to provide high-speed access to large business users. The focus of this chapter is the telephone and cable companies placing a significant emphasis on the development of networks that will allow them to provide a variety of services to individual homes and small to medium businesses. 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, several upgrade options of the PON approach that provide higher capacities by making clever use of wavelength division multiplexing techniques are also explored.