The IEEE standard is a new specification developed in wireless communication which provides very high data rates up to 54 Mbps. In this paper the performance of IEEE standard 802.11a is evaluated in a WLAN environment under three different fading modes that is dispersive fading mode flat fading mode and no fading mode for two modulation schemes BPSK and QPSK. In this paper we are going to understand and find out the main causes for fading of the transmitted signal over the channel path. The parameters which we measure are signal to noise ratio (SNR), bit rate and bit error rate (BER) by which we can evaluate the system performance.