Spatio-temporal equalization and multiuser detection for DS-CDMA systems: a semi-blind approach

A novel strategy for semi-blind spatio-temporal equalization and multiuser detection for short-burst asynchronous DS-CDMA systems is proposed. The technique is based on first performing channel identification (through a semi-blind subspace-based algorithm) as an aid for semi-blind equalization (via the constant modulus algorithm (CMA)). This two step process allows us to improve upon the traditional training-based least squares (LS) estimator by adding the constant modulus and cyclostationary properties of communication signals. Simulation results comparing the performance of our algorithm with regularized LS estimators (both training-based and semi-blind) for different amounts of spatial-diversity, number of active users and burst lengths indicate a significant reduction in the required number of training symbols. Application of this work is in the reverse-link of third generation DS-CDMA systems.