Performance of DSTTD MC-IDMA system for downlink communications

In this paper, we consider the performance of double space time transmit diversity (DSTTD) assisted multiple input multiple output (MIMO) multi-carrier (MC) interleave division multiple access (IDMA) scheme over correlated frequency-selective channels for downlink (DL) transmission. In IDMA user specific interleavers are used as user-separation whereas in conventional code division multiple access (CDMA), orthogonal spreading sequence is used as user specific. In our considered work, Multi-carrier modulation is carried out by IFFT block at the transmitter and FFT block at the receiver. In our considered work, non linear multi-user detection (MUD) based on maximum a-posteriori (MAP) ordered zero forcing (ZF) is employed at the receiver to mitigate the effects of multiple access interference (MAl) and multi stream interference (MSI). In particular, we evaluate the performance of DSTTD MC-IDMA for turbo coded system considering realistic channel model based on Standard University Interim (SUI) specifications. It is shown through the simulation results that DSTTD MC-IDMA can support large user-population and it provides better performance in terms of achievable bit error rate (BER) by invoking iterative decoding algorithm at the mobile stations with reduced number of antennas.