Orthogonal frequency-division multiplexing

From Wikipedia, the free encyclopedia
Jump to: navigation, search
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[change | edit source]

Advantages[change | edit source]

  • 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[change | edit source]

Uses[change | edit source]

Many technologies use OFDM. Among them are: