We consider multiuser interference suppression for direct-sequence spread-spectrum multiple-access (DS/CDMA) system without knowledge of other user's spreading waveforms using the minimum mean squared error (MMSE) performance criterion. The conventional MMSE detectors require training sequences for adaptive implementation. The previously proposed mean output energy (MOE) detector  using canonical representation requires no more knowledge than does the conventional single -user receiver: no more desired user's signature waveform and its timing. But this MOE detector's blind adaptive algorithm is so noisy as to perform worse than the conventional LMS algorithm with a training sequence. And the MOE detector's MMSE solution is greater than that of the conventional MMSE detectors.
In this paper we propose an MOE detector with decision - feedback to improve upon the dynamics of the blind adaptive algorithm and an MMSE detector using new canonical representation which converges to the conventional MMSE detector without requiring training data sequences. The simulation results are given to verify that the performance of two new proposed detectors is better than that of the previous MOE detector. The simulation is also carried out with imprecise knowledge of the received signature waveform of the user of interest.