Performance of interleaved serial concatenated convolutional codes with DSS/DPSK multicarrier modulation in a Doppler spread channel

We study a direct sequence spread spectrum DPSK multicarrier system combined with the interleaved serial concatenated convolutional codes. This combination of error correction coding and modulation is both powerful and flexible. In this paper, we study the effects of increasing the data rate by transmitting information bits in parallel on the multicarrier channel in a Doppler spread environment. Overall bandwidth is kept constant by decreasing the number of chips per channel symbol as the number of carriers increases. Each subchannel of the multicarrier channel is assumed to be frequency non-selective but fade independently of the others subchannels. Results are shown for several fading cases. In addition, it is noted that the performance gained by iterating more than 4 times is not significant.