44 Copyright © 2010, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. Chapter 3 Active Optical Access Networks Gerasimos C. Pagiatakis School for Pedagogical and Technological Education (ASPETE), Greece INtrODUctION: bAcKGrOUND This chapter deals with the active optical access networks, usually referred to as AONs. In this type of optical access networks, sharing of optical fibers among users is implemented by means of active equipment, as opposed to the multiple-passive- splitter approach employed in passive optical networks –PONs– (Venieris, 2007). Generally speaking, an optical access network can be considered as the optoelectronic infrastructure installed in the access part of the telecom network, that is the part between the subscriber and the local exchange (Figure 1). This infrastructure contains both active equipment, (installed in the customer premises, the local exchange and sometimes in AbstrAct 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 fbers among users is implemented by means of active equipment (as opposed to passive optical networks –PONs– where sharing is achieved by using multiple passive 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 fber-interconnected to a local exchange unit, known as Optical Line Termination (OLT). In AONs (as well as in PONs) the optical fber (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 fber becomes directly available to the normal user. Despite the obvious fnancial and techno- economical 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. DOI: 10.4018/978-1-60566-707-2.ch003