Orthogonal Frequency Division Multiplexing (OFDM) is a very potential technique for transmitting high bit rate data over indoor and outdoor wireless communication channels with high bandwidth efficiency and robustness to multipath delay. OFDM is a multichannel modulation that divides a given channel into many parallel sub-channels or subcarriers, so that multiple symbols are sent in parallel. The first multichannel modulation systems appeared in the 1950's as military radio links, best characterized as frequency-division multiplexed systems. The first OFDM schemes were presented by Chang and Saltsburg, in which actual use/ practicability of OFDM was limited. However, later on the OFDM was made more practical through work describe in the article uses Discrete Fourier transform (DFT) with a cyclic prefix. The DFT implemented with a Fast Fourier Transform (FFT)) and the cyclic prefix have made OFDM both practical and attractive to the radio link designer. A similar multichannel modulation scheme, Discrete Multi-Tone (DMT) modulation, has been developed for static channels such as the digital subscriber loop.
