Trellis coded STBC based OFDM for frequency Selective Fading Channels

Multiple-input multiple-output (MIMO) wireless communication system exploits the multiple spatial channels to achieve higher data rate or improved performance in multipath fading environment. Different types of diversity techniques such as temporal, frequency, code and spatial have been developed in the literature. In addition to the destructive multipath nature of wireless channels, frequency selective channels pose inter symbol interference (ISI) while offering frequency diversity for successfully designed systems. Orthogonal frequency division multiplexing (OFDM) has been shown to combat ISI extremely well by converting the frequency selective channel into parallel at fading channels. The space-time block coding (STBC) technique, one of representative multiple antenna techniques, is most attractive for these purposes since it easily provides the diversity at receiver by transmitting a space-time coded signal through multiple antennas. However, these coding techniques are not designed for higher coding gains; hence a novel approach would be to concatenate them with Trellis codes to obtain maximum gain over the frequency selective fading channels. So by using OFDM along with STBC make the frequency selective fading channel into which converts a frequency-selective channel into parallel independent frequency-flat sub channels using the computationally-efficient Fast Fourier Transform (FFT).In order to still enhance the performance of the STBC-OFDM system, one can think of concatenating a convolution code to the STBC-OFDM .As TCM provides coding gain besides error correction, TCM is opted here.