Performance Comparison of M-PSK and M-QAM Modulations for WiMAX OFDM system under the Rayleigh Fading Channel

With the increasing bandwidth and number of users of wireless communication demand of higher bitrates system for wireless digital transmissions has also increased. Since number of users are increasing thus the capacity of the wireless communication is a major challenge. WiMAX is widely used to serve this purpose. The wireless WiMAX communications are based on OFDM technique with IEEE 802.16e standards. .In this paper, the performance of the M-PSK modulation methods is compared with the M-QAM modulation for wireless WiMAX over the Rayleigh fading channels. The FFT size is kept constant to 64 for performance evaluation. The bit error rate is used as the performance evaluation parameter. Also the effect of the varying the Doppler shifts frequencies on the performance of OFDM under Rayleigh fading have also evaluated. Performance is also compared for different transmitting gains.