A telecommunications company needs to respond quickly to increased bandwidth demands and protocol changes over their existing fiber infrastructure. They need to cover a short distance at minimal cost.

CWDM uses 20 nm channel spacing and uncooled, unrefrigerated lasers which significantly reduce equipment cost compared to DWDM. It supports up to 18 channels and is optimized for short to medium distances (up to ~80 km) over existing fiber, making it ideal for a carrier that needs affordable, quickly deployable capacity upgrades without replacing fiber infrastructure.

Dense Wave Division Multiplexing (DWDM) uses tightly spaced channels (0.8 nm) requiring thermally stabilized lasers and complex amplifiers, making it significantly more expensive and better suited for long-haul transmission rather than low-cost short-distance upgrades.

Space-Division Multiple Access (SDMA) is a radio/wireless channel access technique used in cellular and satellite systems, not a fiber-optic multiplexing technology.

Time-division multiplexing (TDM) combines signals by interleaving them in the time domain and does not increase the optical capacity of existing fiber, making it unsuitable for responding to bandwidth demands over fiber infrastructure.