  This paper is concerned with SC/FDE for bandwidth-efficient uplink block
transmission, with QAM schemes, in a MU MIMO system. The number of BS receiver
antennas is assumed to be large, but not necessarily much larger than the
overall number of transmitter antennas jointly using the same time/frequency
resource at MT.
  In this context, we consider several detection techniques and evaluate, in
detail, the corresponding detection performances (discussed with the help of
selected performance bounds), for a range of values regarding the number of
available BS receiver antennas. From our performance results, we conclude that
simple linear detection techniques, designed to avoid the need of complex
matrix inversions, can lead to unacceptably high error floor levels. However,
by combining the use of such simple linear detectors with an appropriate
interference cancellation procedure - within an iterative DF technique -, a
close approximation to the SIMO MFB performance can be achieved after a few
iterations, even for 64-QAM schemes, when the number of BS antennas is, at
least, five times higher than the number of antennas which are jointly used at
the user terminals.
