Long Term Evolution-Advanced (LTE-A) is a Fourth Generation (4G) standard of wireless communications that introduces high data rate, high performance, and low delay. These features of LTE-A resulted from the new techniques developed for wireless communications such as Multiple-Input Multiple-Output (MIMO) technique. At the heart of this technique is the Space Time Codes, which were developed by the researchers in recent decades to achieve the mentioned features. The designs of OSTBC codes for MIMO systems having any number of transmit antennas and any number of receive antennas have attracted the attention of many researchers. Based on the theory of real and complex orthogonal designs, this paper deals with the design of real and complex OSTBC codes to be used with real signal set constellation such PAM and complex signal constellation such as PSK and QAM. Real and complex OSTBC codes for MIMO systems with two, three, four, five, six, seven and eight transmit antennas and any number of receive antennas, are presented. Simple linear processing ML decoders are derived and presented. The used channel is Rayleigh fading channel MIMO and assumed to behave in a “quasi-static” fashion. Finally, the performances of OSTBC schemes were evaluated and compared in terms of the Bit Error Rate (BER) and Signal to Noise Ratio (SNR). The environment of simulation is MATLAB which is a powerful tool for mathematical calculation and system simulation. The methods of modulations chosen are QPSK, 16QAM, 64QAM, and 128QAM with gray scale mapping
