Abstract:
Multiuser detection techniques are known to be effective
strategies to counter the presence of multiuser
interference in code division multiple access channels.
Generally, multiuser detectors can provide excellent
performance only when the signature waveforms1 of all
users are precisely known. Hence, the estimation of
signature waveforms is a challenging issue in mobile
communication systems. In this paper, we compare the
performance of two training based estimators of using
short training sequences. One is maximum likelihood
type signature waveform estimator that requires the
knowledge of spreading sequences and training
sequences. The other estimator is based on subspace
method and requires the knowledge of training sequences
only. Through the simulations, we show the signature
waveform estimation performance of both systems and
the effect of the estimation error on the performance of a
multiuser detector. The complexity comparisons of both
systems are also given.
