Chapter 11 - OFDM Applications in Access Optical Networks

Abstract

Orthogonal frequency-division multiplexing (OFDM) as a technology that enables robust transmission over both wireless and optical channels has already been employed in many communication standards, including wireless local area network (LAN; also known as Wi-Fi), digital video and audio broadcasting standards, digital subscribed loop (DSL), and Worldwide Interoperability for Microwave Access (WiMAX, or IEEE 802.16). WiMAX is a wireless technology that provides wireless last mile broadband access with fast connection speeds comparable to T1, cable, and DSL data rates. WiMAX provides up to 75 Mb/s over ranges up to 30 miles. WiMAX is the technology that brings the network to the building, whereas end users can be connected using wireless LAN, Ethernet, or plastic optical fibers (POFs). The working group responsible for WiMAX is IEEE 802.16, which initially developed the standard for the 10- to 66-GHz portion of the spectrum. This region of frequencies requires line-of-sight (LOS) between the transmitting and receiving antennas. Because of the need for high antennas, focus has shifted to the 2- to 11-GHz portion of the spectrum, which does not require LOS (IEEE 802.16a standard).