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Orthogonal frequency-division multiplexing

From Simple English Wikipedia, the free encyclopedia
An example of OFDM, with 4 different signals, shown in different colors

Orthogonal Frequency Division Multiplexing is a technology related to Frequency Division Multiplexing. With it, many different signals can be sent over the same medium, at the same time. Each signal uses a different basis function. By using the basis function given, the sender and recipient will then see their signal better, the other signals will be clearly separated.

Advantages and disadvantages

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Advantages

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  • Can adapt easily to bad channels (noisy,etc.)
  • Robust against crosstalk between channels that are close together.
  • Robust against Intersymbol interference (ISI) and fading caused by multipath propagation
  • High spectral efficiency
  • There are good implementations available
  • Few problems with errors that come from time synchornization
  • Tuned sub-channel receiver filters are not required (unlike conventional FDM)
  • Facilitates Single Frequency Networks, i.e. transmitter macrodiversity.

Disadvantages

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Many technologies use OFDM. Among them are: