Iterative Channel Estimation for Frequency-Domain Equalization of DSSS Signals

Kazuaki TAKEDA
Fumiyuki ADACHI

IEICE TRANSACTIONS on Communications   Vol.E90-B    No.5    pp.1171-1180
Publication Date: 2007/05/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e90-b.5.1171
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
DSSS,  frequency-domain equalization (FDE),  channel estimation,  

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As the channel frequency selectivity becomes severer, the bit error rate (BER) performance of direct sequence spread spectrum (DSSS) signal transmission with rake combining degrades due to an increasing inter-path interference (IPI). Frequency-domain equalization (FDE) can replace rake combining with much improved BER performance in a severe frequency-selective fading channel. For FDE, accurate estimation of the channel transfer function is required. In this paper, we propose an iterative channel estimation that uses pilot chips which are time-multiplexed within each chip block for fast Fourier transform (FFT). The pilot acts as a cyclic-prefix of FFT block as well. The achievable BER performance is evaluated by computer simulation. It is shown that the proposed channel estimation has a very good tracking ability against fast fading.