OFDM is a new scheme for data transmission with several advantageous features. In this report a survey of all existing OFDM systems are being presented. Starting with simple FFT based OFDM the other variants like DCT-OFDM, Interspersed OFDM and DWT based OFDM are studied.-OFDM is a new scheme for data transmission with several advantageous features.　In this report a survey of all existing OFDM systems are being presented.　Starting with simple FFT based OFDM　the other variants like DCT-OFDM, Interspersed OFDM and DWT based OFDM are studied.