Blind Multiuser Detection for a Multi-Satellite DS/CDMA System

We address blind multiuser detection for a DS/CDMA satellite network employing path diversity. Diversity is realized by resorting to simultaneous transmission between users and multiple satellites which, in turn, retransmit the composite received signals to a fixed earth station. A blind decorrelating detector exploiting knowledge of the set of the N admissible spreading codes is proposed; it assumes knowledge of the carrier shifts, and of the code of the user of interest. The number and the identity of interferers, together with their channels are determined from the observables. The performance assessment of the proposed detector shows that it outperforms a plain subspace-based blind decorrelator for small sizes of the estimation sample, but also that it is very sensitive to possible mismatches between nominal and actual carrier shifts. Finally, a modified version of the proposed detector, capable to work with coarse estimates of the carrier shifts, is also introduced.