U. Madhow et Ml. Honig, MMSE INTERFERENCE SUPPRESSION FOR DIRECT-SEQUENCE SPREAD-SPECTRUM CDMA, IEEE transactions on communications, 42(12), 1994, pp. 3178-3188
We consider interference suppression for direct-sequence spread-spectr
um code-division multiple-access (CDMA) systems using the minimum mean
squared error (MMSE) performance criterion. The conventional matched
filter receiver suffers from the near-far problem, and requires strict
power control (typically involving feedback from receiver to transmit
ter) for acceptable performance. Multiuser detection schemes previousl
y proposed mitigate the near-far problem, but are complex and require
explicit knowledge or estimates of the interference parameters. In thi
s paper, we present and analyze several new MMSE interference suppress
ion schemes, which have the advantage of being near-far resistant (to
varying degrees, depending on their complexity), and can be implemente
d adaptively when interference parameters are unknown and/or time-vary
ing. Numerical results are provided that show that these schemes offer
significant performance gains relative to the matched filter receiver
. We conclude that MMSE detectors can alleviate the need for stringent
power control in CDMA systems, and may be a practical alternative to
the matched filter receiver.