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