The demand for high-speed mobile wireless communications is rapidly growing. Orthogonal Frequency Division Multiplexing (OFDM) technology promises to be a key technique for achieving the high data capacity and spectral efficiency requirements for wireless communication systems of the near future. OFDM is a bandwidth efficient multicarrier modulation where the available spectrum is divided into subcarriers, with each subcarrier containing a low rate data stream. OFDM has gained a tremendous interest in recent years because of its robustness in the presence of severe multipath channel conditions with simple equalization, robustness against Inter-symbol Interference (ISI), multipath fading, in addition to its high spectral efficiency.Different modulation techniques are employed to modulate the parallel carriers. This work investigates the bit error rate performance of OFDM for different modulation techniques and compared them.This work also investigates high peak-to-average power ratio (PAPR) problem of OFDM for large number of sub-carriers, which result in many restrictions for practical applications.