Adaptive multiuser bootstrapped decorrelating CDMA detector for one-shot asynchronous unknown channels

Vast research was recently performed on signal detection of multiuser code division multiple access (CDMA). Particularly for uplink (users to base station) the signals are asynchronous and the near-far problem is an important issue to deal with. All near-far resistant detectors, adaptive or non-adaptive, assume knowledge of the relative delays of the different users signals. Among these are the one-shot detectors suggested by Verdu. In this paper we suggest an adaptive algorithm to decorrelate the outputs of the one shot matched filters that assumes no knowledge of the relative delay. The performance of this approach is shown to be better than the non-adaptive “zero-forcing” method previously used and which implements linear transformation via the inverse of matched filters output cross-correlation. For simplicity a two-user case is presented. Extension to a higher number of users is relatively simple