ABSTRACT

In this thesis, we investigated on antenna diversity techniques in wireless communication systems that employ multiple transmitting and receiving antennas to achieve spatial diversity, mitigate signal fade and to increase the data rate transmission without increasing bandwidth channels. In particular, we focused on Alamouti s (STBC) transmit diversity technique, a technique with N transmitting simulation tool, we provided simulation results demonstrating the performance for two transmit and one, two, three and four receive antennas over Rayleigh fading channel. We illustrated that using multiple transmit antennas and space-time block coding outstanding performance could be obtained, under the impact of channel fading. The signal detection algorithm used in this technique was based on maximum likelihood detector for receiving the original data from the received signals on the M antennas. The result from the simulation obtained over Rayleigh channel using two transmitting antennas and different receiving antennas. It was observed that whenever the numbers ofreceiving antennas were increased the performance of the system increased i.e. form signal quality point of view the reception of multiple copies of the transmitted data decreased the error probability of the system. It was also observed that the bit error rate increased as M increased. From the channel capacity point of view, it demonstrated that multiple antennas had the potential to dramatically increase the achievable data rates, thus converting wireless channels from narrow to wide data channel. Space-time block codes (STBC) realised these gains by introducing temporal and spatial correlations into the transmitted signals from different antennas without increasing the total transmitted power or transmission bandwidth.