Precoder Based Collaborative Blind Multiuser Detection of CDMA Signals

A new collaborative blind multiuser detection scheme based on precoding and signal subspace estimation is proposed for binary phase-shift keying/direct-sequence code-division multiple-access signals. In this scheme, precoding the phase of the data enables separation and detection of a desired user’s signal from the received signal with the prior knowledge of only the precoding sequence, signature waveform and timing of the user of interest. In this approach, instead of assigning unique precoding sequence to each user, same precoding sequence is assigned to a group of users which enables group precoding and deprecoding operations. The proposed collaborative blind multiuser receiver consists of two stages: group deprecoding stage to minimize multiple-access interference due to multiple groups in the system and blind subspace multiuser detection stage to detect desired user data from the respective group. The simulation results confirm that the performance gain afforded by the proposed scheme can be substantial when compared to the conventional linear subspace blind detectors.