Bit Error Rate Performance of 4x2 Space-Time MIMO-OFDM Conjugate Cancellation Techniques

Wireless communication is a central aspect of our everyday lives. Currently, the main goal in wireless communication research, is to find efficient methods to improve signal transmission by improving the Bit Error Rate (BER) performance of mobile communication systems. To improve the BER performance, the Inter-Carrier Interference (ICI) during signal transmission must be mitigated. The ICI can be caused by conditions such as residual carrier frequency offset, time variations because of the Doppler shift or phase noise; these conditions destroy the orthogonality at the receiver and subsequently degrade the BER performance of mobile communication systems. This thesis work involves the implementation of a 4x2 Space-Time Conjugate Cancellation-Orthogonal Frequency Division Multiplexing (STCC-OFDM) system to mitigate ICI and compares its BER performance to a previously established 4x1 STCC-OFDM system. The 4x1 STCC-OFDM system employs four transmitting antennas and one receiving antenna whereas the 4x2 STCC-OFDM system employs four transmitting antennas and two receiving antennas. The auxiliary antenna employed in the 4x2 STCC-OFDM system provides spatial diversity and redundant data at the receiver side. Results show that the 4x2 STCC-OFDM system has better BER performance compared to the 4x1 STCC-OFDM system. Additionally, all the simulations are performed on MATLAB R2015b software. These simulations show the BER variation at different Signal to Noise Ratio (SNR) values for the 4x1 STCC-OFDM and the 4x2 STCC-OFDM systems, with code rates 1 and 0.5 in COS 207 channel. Simulations indicate that as the value of SNR increases the BER value comes down. BER values of the 4x2 STCC-OFDM system are significantly lower than the 4x1 STCC-OFDM system for both the code rates 1 and 0.5. Finally, the result of the simulations shows that the 4x2 STCC-OFDM system is more efficient than the 4x1 STCC-OFDM system