Abstract: OFDM is a frequency-division multiplexing (FDM) system used as a digital multi-carrier modulation method. A large number of closely spaced orthogonal sub-carrier signals are used to carry data on several parallel data current or channels. In this paper, BER performance of MIMO (Multi-Input Multi-Output) OFDM system has been compared for AWGN channel, Rayleigh fading channel and Rician fading channel. Later analyze how with different value of Diversity parameter BER performance of Rayleigh fading channel and Rician fading channel has been effected. This paper has been divided into two parts. In first part basic functionof OFDM has been introduced and then in second part BER performance of OFDM has been analyzed.

Keywords: IFFT, Cyclic prefix, ISI, AWGN, Rayleigh, Rician, BER, Matlab, MIMO, OFDM.