Space-time blind code synchronization for asynchronous CDMA systems with decision feedback

A novel space-time adaptive near-far robust code synchronization array-detector for asynchronous DS-CDMA systems is developed. For real-time applicability, a computationally efficient architecture of the proposed detector based on the concept of the multistage Wiener filter (MWF) of J.S. Goldstein et al. is developed (see IEEE Trans. Info. Theory, vol.44, p.2943-59, 1998). This multistage technique results in a self-synchronizing detection criterion that requires no inversion or eigen-decomposition of a covariance matrix. As a consequence, this detector achieves a complexity that is only a linear function of the size of antenna array (J), the rank of the MWF (M), the system processing gain (N), and the number of samples in a chip interval (S), i.e., O(JMNS). Simulations are conducted to evaluate the performance and convergence behavior of the proposed detector with the size of the J-element antenna array and the rank of the M-stage MWF. The performance advantage of the proposed detector over the Neyman and Pearson (NP) DS-CDMA detector is investigated as well.