Pilot-assisted Channel Estimation for Overlap FDE of DS-CDMA Signals

Overlap frequency-domain equalization (FDE) requires no guard interval (GI) insertion while achieving the frequency diversity gain and hence can be applied to the present cellular systems using direct sequence-code division multiple access (DS-CDMA). It has been confirmed that assuming the ideal channel estimation, overlap FDE can provide almost the same bit error rate (BER) performance as the conventional FDE using GI insertion. In this paper, we propose a pilot-assisted channel estimation suitable for overlap FDE, in which a short pilot chip sequence is repeated twice in the chip block so that the received pilot sequence becomes a circular convolution between the transmitted pilot sequence and channel impulse response. We evaluate by computer simulation the BER performance achievable by the proposed pilot-assisted channel estimation in a frequencyselective Rayleigh fading channel. Keywords— Overlap FDE, pilot-assisted channel estimation, DSCDMA