Orthogonal Frequency Division Multiplexing (OFDM) is an application of frequency division multiplexing where the adjacent signals are separated by a frequency that is the inverse of the symbol duration period. This gives the signals the special property that they are "orthogonal" to each other, eliminating crosstalk between them. In terms of spectral energy, a null will occur where each neighboring signal is located.
See also: Wikipedia article
OFDM
OFDM Tutorial from Complex to Real
Wireless Communications Resources Collection
Transceiver and System Design for Digital Communications
OFDM Tutorial Applet
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