Orthogonal frequency Division Multiplexing (OFDM) is multicarrier transmission technique. OFDM is a communication technique that divides the communication channel into a number of equally spaced frequency bands. A sub carriers a portion of the users information in each band. Each sub carriers is orthogonal (Independent of each other) with every other sub carrier. OFDM efficiently squeezes multiple modulated carriers tightly together reducing the required bandwidth.OFDM was invested in 1960?s, only recently it has recognized as an excellent method for bi-directional wireless data communication. It is extremely efficient in mitigating common problems in high-speed communication such as multipath fading and RF noise interference. It can be considered as multiple access technique OFDMA..