Impact of Spreading Factor on Turbo-coded Multi-code MC-CDMA using ICI cancellation

Multi-carrier code division multiple access (MC-CDMA) is one of promising broadband wireless access techniques. Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can take advantage of the channel frequency-selectivity and improve the average bit error rate (BER) performance of single-code MC-CDMA due to frequency-diversity gain. However, as the code multiplexing order is increased so as to increase the data rate without bandwidth expansion, the presence of residual inter-code interference (ICI) degrades the transmission performance. Recently, we proposed a frequency-domain adaptive interference cancellation (FDAIC) technique to mitigate the residual ICI and showed that the full code multiplexed MC-CDMA with FDAIC achieves better performance than orthogonal frequency division multiplexing (OFDM). However, the impact of spreading factor was not discussed. In this paper, we evaluate, by computer simulation, the average BER and throughput performances of turbo-coded MC-CDMA with FDAIC for different values of spreading factor, and show that the full-code multiplexed MC-CDMA with FDAIC using the full spreading factor (equal to the number of subcarriers) can provide almost the same or better transmission performance than OFDM.