Which multiplexing technique assigns distinct frequency bands to signals for simultaneous transmission?

• A. FDM
• B. TDM
• C. QAM
• D. OFDM

Answer: (A)

Frequency Division Multiplexing is the method that assigns distinct frequency bands to individual signals so they can be transmitted simultaneously without interfering with each other. Each signal is carried on its own carrier at a unique frequency, and guard bands between the bands help prevent overlap. This lets multiple conversations or data streams share the same overall channel, which is why FDM is commonly used in traditional analog telephone trunks and radio broadcasting. Other options don’t describe this frequency-based sharing: one is about splitting time rather than bandwidth, another is a modulation scheme for encoding data on a carrier, and the last is a modern multi-carrier technique that relies on closely spaced, orthogonal subcarriers within the same spectrum rather than fixed, separate frequency bands.