Performance analysis for differential STBC and SFBC MIMO- OFDM systems under different modulation schemes in a Rayleigh channel

Orthogonal frequency division multiplexing (OFDM) has become a prevalent and widespread technique for the broadcast and transmission of signals over wireless channels and has been adopted in many wireless standards. OFDM may be united with antenna arrays at the transmitter and receiver side to enhance the diversity gain and to improve the system competence on time-variant and frequency-selective channels, resulting in a multiple-input multiple-output (MIMO) composition. The space-time block coding (STBC) for OFDM systems with multiple transmit antennas is a type where coding is applied in the time domain (OFDM symbols). In particular Alamouti´s code is considered, which is shown to be the most favourable block code for two transmit antennas and time domain coding. The Differential Space time codes are ways of transmitting data in wireless communications and they are forms of space time codes that do not need to know the channel impairments at the receiver side in order to be able to decode the signal. A Performance Analysis study is investigated for different DSTBC MIMO OFDM Systems under Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), 16-Quadrature Amplitude Modulation (16-QAM) and 64-Quadrature Amplitude Modulation (64-QAM) schemes and its performance is evaluated in terms of Bit Error Rate under Rayleigh Multipath channel.