Iterative Overlap FDE for DS-CDMA without GI

Frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion can replace the conventional rake combining with significantly improved bit error rate (BER) performance for the downlink DS-CDMA in a frequency-selective fading channel. Recently, a new MMSE-FDE technique that requires no GI insertion has been proposed to avoid inter-block interference (IBI) (this technique is called overlap FDE). However, the residual IBI is produced and degrades the BER performance. Furthermore, the presence of an inter-chip interference (ICI) after MMSE-FDE limits the BER performance improvement. In this paper, we propose an iterative overlap FDE for DS-CDMA downlink to suppress both IBI and ICI. In the iterative overlap FDE, joint MMSE-FDE and ICI cancellation is repeated a sufficient number of times and the middle part of M chips is picked up. The BER performance with the iterative overlap FDE is evaluated by computer simulation.