DS-CDMA MMSE turbo equalization using 2-step maximum likelihood channel estimation

Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion and frequency-domain inter-chip interference (ICI) cancellation can be incorporated into turbo decoding (this is called the MMSE turbo equalization in this paper) to improve the bit error rate (BER) performance for direct sequence code division multiple access (DS-CDMA). DS-CDMA MMSE turbo equalization requires accurate channel estimation. The performance of MMSE turbo equalization is sensitive to channel estimation accuracy. Recently, we proposed a 2-step maximum likelihood channel estimation (MLCE) for DS-CDMA with FDE. In this paper, we apply 2-step MLCE to DS-CDMA MMSE turbo equalization and evaluate by computer simulation the achievable BER performance in a frequency-selective block Rayleigh fading channel.