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A Blind Adaptive CDMA Receiver Based on State Space Structures
Code Division Multiple Access (CDMA) is a channel access method, based on
spread-spectrum technology, used by various radio technologies world-wide. In
general, CDMA is used as an access method in many mobile standards such as
CDMA2000 and WCDMA. We address the problem of blind multiuser equalization in
the wideband CDMA system, in the noisy multipath propagation environment.
Herein, we propose three new blind receiver schemes, which are based on state
space structures and Independent Component Analysis (ICA). These blind
state-space receivers (BSSR) do not require knowledge of the propagation
parameters or spreading code sequences of the users they primarily exploit the
natural assumption of statistical independence among the source signals. We
also develop three semi blind adaptive detectors by incorporating the new
adaptive methods into the standard RAKE receiver structure. Extensive
comparative case study, based on Bit error rate (BER) performance of these
methods, is carried out for different number of users, symbols per user, and
signal to noise ratio (SNR) in comparison with conventional detectors,
including the Blind Multiuser Detectors (BMUD) and Linear Minimum mean squared
error (LMMSE). The results show that the proposed methods outperform the other
detectors in estimating the symbol signals from the received mixed CDMA
signals. Moreover, the new blind detectors mitigate the multi access
interference (MAI) in CDMA