This paper addresses the issue of blind multiuser detection in dispersive channels of CDMA in the presence of both multiple-access interference (MAI) and intersymbol interference (ISI). By applying the theory of blind multiple-input, multiple-output (MIMO) channel equalization, it is shown that under certain conditions the multiuser information symbols can be recovered without any prior knowledge of the channel or the user’s signature waveform, though the algorithmic complexity of such an approach is prohibitively high.


These observations gave rise to a significant effort to develop a suboptimal receiver as a midway approach between low-performance matched-filter (MF) detector and optimum multiuser (MU) detector.