ABSTRACT
This chapter presents the analysis of transmission. Since transmission is performed almost only via optical fibers, it deals with to optical transmission systems for metro and core networks. The chapter explores the most basic system: intensity modulation direct detection systems without optical amplifiers. It considers the optical systems for long-haul and ultra-long-haul transmission. The chapter analyses the hardware architecture of a transmission system, putting into evidence those issues, like power consumption and real estate occupation, that in practice are often more important than one more channel at 10 Gbit/s. The modulated signal is launched in the transmission line that is constituted by a transmission fiber interrupted by online sites where the optical signal is processed, for example, amplified, filtered, regenerated, and so on, depending on transmission needs. In all transmission systems, noise and other signal distortions are introduced at various points; thus, the extraction of the transmitted symbols from the received signal is a statistical operation prone to errors.
