Active Optical Access Networks

In this chapter, active optical access networks (AONs) are examined. AONs are a special type of optical access networks in which the sharing of optical fibers among users is implemented by means of active equipment (as opposed to passive optical networks –PONs– where sharing is achieved by using multiplepassive splitters). In active optical access networks, user-side units, known as Optical Network Units (ONUs), are usually grouped in access Synchronous Digital Hierarchy (SDH) rings and fiber-interconnected to a local exchange unit, known as Optical Line Termination (OLT). In AONs (as well as in PONs) the optical fiber (originally used in the trunk network) is introduced in the access domain, namely between the customer and the local exchange. Practically, this means that the huge bandwidth provided by the optical fiber becomes directly available to the normal user. Despite the obvious financial and technoeconomical issues related to the massive deployment of optical access networks, the possibilities and challenges created are enormous. This chapter examines the various units and modules composing an active optical access network and presents the basic procedures for implementing such a network.