Joint detection of timing and identity of users in a chip-synchronous multiuser CDMA system

A scheme for blind estimation of users´ timings in a chip-synchronous direct sequence code division multiple access (DS-CDMA) system is presented. Users are assumed symbol-asynchronous. In addition to the timing estimation, the proposed scheme also provides user identification. Neither advance knowledge of the spreading codes, nor any training sequence is required. The proposed approach is based on subspace decomposition and searches for a solution that minimizes a defined cost function. The search is performed over both signal space and time domain.