Super-exponential methods for blind detection of asynchronous CDMA signals over multipath channels

Code-constrained super-exponential algorithms (SEA) are presented for blind detection of asynchronous short-code DS-CDMA (direct sequence code division multiple access) signals over multipath channels. Only the spreading code of the desired user is assumed to be known; its transmission delay may be unknown. By exploiting the fact that the equalizer always lies in a subspace associated with the desired user's code sequence, a projection operator is imposed at every iteration so that the algorithm can extract the desired user. The results are further improved by following the constrained SEA by unconstrained SEA. An illustrative simulation example is provided