This paper presents an improved two-stage decorrelating detection scheme fo
r direct-sequence code-division multiple-access (DS-CDMA) systems. Decorrel
ator outputs corresponding to each user are tested to determine whether or
not a final decision can be made with high reliability. For users with high
reliability, a hard decision is made at this stage. For the remaining user
s, a conditional quantization algorithm is employed before a decision is ma
de, Results indicate that significant performance enhancement can be achiev
ed at the expense of a modest increase in computational complexity. The alg
orithm is also applied to synchronous as well as asynchronous multipath cha
nnels with excellent results. We also extend the two-stage decorrelating de
tection scheme to time-variant communication scenarios and present:ln adapt
ive version of the two-stage decorrelator.