Space time frequency diversity techniques for orthogonal frequency division multiplexing using multiple input multiple output channels / Suhaila Abdul Rahman

In telecommunications, multi antenna communication systems with orthogonal frequency division multiplexing (OFDM) have the potential to play an important role in the design of the next generation broadband wireless communication systems. This paper proposes novel space time frequency block code (STFBC) diversity for OFDM transmissions over frequency selective Rayleigh fading channel by using 64 QAM and 256 QAM modulation scheme with insertion Maximum Likelihood Decoding process by using Linear Equalizer. In this research, we will deal with four transmit antennas and three receive antennas. As will be shown, the performance of diversity system depends on the combining scheme in order to choose the highest signal to noise ratio (SNR) and lowest noise by using free selective fading chanel. The design of STFBC is to achieve full spatial diversity against Rayleigh fading channel. A comparison will be made, which OFDM modulation techniques with propose double decode (Cyclic Decoding and Maximum Likelihood Decoding) will give better result in diversity technique and to prove that diversity better than no diversity base on bit error rate (BER). The result shows that 256 QAM Modulation techniques is having better performance compared to 64 QAM Modulation Techniques. This project use MATLAB version R2007a to simulate the performance of STFBC.