Orthogonal frequency-division multiplexing

Orthogonal frequency-division multiplexing

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.

An example of OFDM, with 4 different signals, shown in different colors

Advantages and disadvantagesEdit

AdvantagesEdit

  • 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.

DisadvantagesEdit

UsesEdit

Many technologies use OFDM. Among them are: