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frequency division multiplexing (FDM)

In frequency division multiplexing (FDM), a wide frequency band is divided into several narrower frequency bands. Each of these frequency bands corresponds to a separate transmission channel. This multi-carrier modulation works with several independent carrier frequencies, whereby each individual carrier signal is modulated and transmitted completely independently of other carrier frequencies with different data streams.

In frequency division multiplexing, multiple modulated frequencies are transmitted simultaneously over the transmission channel. Depending on the concept, the bandwidth of the transmission channels can be the same or different.

Principle of frequency

Principle of frequency

division multiplex To avoid overlapping of the individual subcarrier bands and mutual interference, a guard frequency band is placed between the adjacent carrier frequencies.

Frequency

Frequency

division multiplex
with subcarrier bands separated by guard bands

with subcarrier bands separated by guard bands

A variant of frequency division multiplex is frequency division duplex (FDD) in which the uplink and downlink radio channels between the receiving and base stations are separated and transmitted on different frequencies. An extremely bandwidth-efficient variant of frequency division multiplex is orthogonal frequency division multiplex (OFDM), which uses a much smaller frequency band for the same transmission rate.

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Englisch: frequency division multiplexing - FDM
Updated at: 26.04.2016
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