ABSTRACT
This chapter shows that transmission systems with an overall capacity in excess of 2 Tbit/s and a reach longer than 2000 km can be designed using direct detection and in-line optical amplification. It analyses the real potentialities of the different system architectures when practical requirements are set. Several other architectures have been proposed for the Tunable Optical Dispersion Compensators, having different characteristics. As a matter of fact, the need of a new generation of transmission systems does not emerge from the need of increasing the transmission capacity or the system reach, but comes from other reasons. In general, solutions to transmission impairments can be attained either via the use of suitable devices to eliminate or compensate the impairing effect or shaping the transmission format and the detection strategy to be less sensible to the considered effect. The only possible solution is to try to shrink the transmitted signal bandwidth by using suitable transmission formats.
