Orthogonal Frequency Division Multiplexing

What Does Orthogonal Frequency Division Multiplexing Mean?

Orthogonal frequency division multiplexing (OFDM) is a technique, method or scheme for digital multi-carrier modulation using many closely spaced subcarriers – a previously modulated signal modulated into another signal of higher frequency and bandwidth. Each of these subcarriers contains numbers of parallel data streams or channels and is modulated conventionally at a low symbol rate; these are groups of bits of data related to (but not the same as) gross bitrate, which is expressed in bits/second.

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This term is also known as coded OFDM (COFDM) and discrete multi-tone modulation (DMT), used for both wireless and physical communication mediums.

Techopedia Explains Orthogonal Frequency Division Multiplexing

The term “orthogonal” is actually an adjective describing two things acting independently or in an uncorrelated manner; in this case, any two signals of an OFDM-based product operating without dependence on, or interference with, one another.

OFDM is used for wideband digital communication, which is commonly used for digital television and audio broadcasting (radio) as well as broadband Internet access and wireless networking. OFDM is very similar to FDM (frequency division multiplexing) but with technology purposely emphasizing the minimization of crosstalk or signal interference from other nearby signal carrying communication mediums. OFDM uses many narrow band signals as opposed to a signal modulated at a high symbol rate and a large bandwidth.

OFDM-based products include:

  • Certain types of broadband access through POTS (plain old telephone service) copper wiring
  • Power line communication (PLC)
  • Multimedia over Coax Alliance (MoCA) home networking
  • Some digital radio systems
  • Some digital TV systems
  • Some mobile TV systems
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Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.