Alamouti’s space-time coding scheme for Multi-Input Multi-Output (MIMO) system has drawn much attention in 4G wireless technologies. Orthogonal frequency division multiplexing (OFDM) is a popular method for high data rate wireless transmission. OFDM may be combined with antenna arrays at the transmitter and receiver to increase the diversity gain and enhance the system capacity on time variant and frequency selective channels, resulting in Multi-Input Multi-Output (MIMO) configuration. This paper explores varies physical layer research challenges in MIMO-OFDM system design including channel modeling, space time block code techniques, channel estimation and signal processing algorithms used for performing time and frequency synchronization in MIMO-OFDM system .The proposed system is simulated in mat lab and analyzed in terms of BER with signals to noise ratio (SNR).The difference of BER for coded and uncoded MIMO system is also analyzed.