Large system performance of linear multiuser receivers in multipathfading channels
Evans, J.; Tse, D.N.C.
Information Theory, IEEE Transactions on
Volume 46, Issue 6, Sep 2000 Page(s):2059 - 2078
Digital Object Identifier 10.1109/18.868478
Summary:A linear multiuser receiver for a particular user in a
code-division multiple-access (CDMA) network gains potential benefits
from knowledge of the channels of all users in the system. In fast
multipath fading environments we cannot assume that the channel
estimates are perfect and the inevitable channel estimation errors will
limit this potential gain. We study the impact of channel estimation
errors on the performance of linear multiuser receivers, as well as the
channel estimation problem itself. Of particular interest are the
scalability properties of the channel and data estimation algorithms:
what happens to the performance as the system bandwidth and the number
of users (and hence channels to estimate) grows? Our main results
involve asymptotic expressions for the signal-to-interference ratio of
linear multiuser receivers in the limit of large processing gain, with
the number of users divided by the processing gain held constant. We
employ a random model for the spreading sequences and the limiting
signal-to-interference ratio expressions are independent of the actual
signature sequences, depending only on the system loading and the
channel statistics: background noise power, energy profile of resolvable
multipaths, and channel coherence time. The effect of channel
uncertainty on the performance of multiuser receivers is succinctly
captured by the notion of effective interference
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