Comparison between WDM and TDM techniques

The present work illustrates the main transmissive issues pertaining to the multiplexing techniques known as WDM (Wavelength Division Multiplexing) and TDM (Time Division Multiplexing). The paper briefly describes the physical and technological limitations of high capacity transmission on optical fibre and the consequent application areas for both technologies. The TDM and WDM techniques are then compared from the economic point of view: in particular by reviewing a case study developed within the scope of European project Eurescom P413 `Optical Networking', which consists of the economic comparison between the two solutions, in two system configurations differing in length and capacity. This comparison shows that, even as of now, WDM may represent an interesting alternative, in terms both of cost-effectiveness and of flexibility. Finally, the ACTS project OPEN is briefly illustrated; in it, the integration of both solutions is proposed within a vision of a single network.