Which Wavelength Division Multiplexing (WDM) solution should an IT department consider for connecting two buildings 3 kilometers apart using a single-mode fiber optic cable?

Coarse Wavelength Division Multiplexing (CWDM) is the appropriate choice for connecting two buildings 3 kilometers apart using single-mode fiber optic cable. CWDM is designed for applications where a large number of wavelengths can be multiplexed over a single fiber, supporting distances of up to approximately 80 kilometers.

Since the distance between the two buildings is relatively short at 3 kilometers, CWDM can effectively utilize the available wavelengths without needing the tighter channel spacing and additional complexity that comes with Dense Wavelength Division Multiplexing (DWDM). CWDM typically has channel spacing of 20 nm, making it simpler and more cost-effective for shorter distances and lower transmission capacity requirements.

In contrast, while DWDM uses much narrower channel spacing and allows for the transmission of more channels over greater distances, it is usually over-engineered for such a short distance, leading to unnecessary complexity and expense.

Frequency Division Multiplexing (FDM) and Time Division Multiplexing (TDM) are not suitable choices in this context, as they do not operate on the principle of combining multiple signals over different wavelengths in fiber optics, which is a fundamental aspect of WDM technologies. FDM is generally used in analog communications, while TDM is used to