  This paper deals with SC/FDE within a MU-MIMO system where a large number of
BS antennas is adopted. In this context, either linear or reduced-complexity
iterative DF detection techniques are considered. Regarding performance
evaluation by simulation, appropriate semi-analytical methods are proposed.
This paper includes a detailed evaluation of BER performances for uncoded
4-Quadrature Amplitude Modulation (4-QAM) schemes and a MU-MIMO channel with
uncorrelated Rayleigh fading. The accuracy of performance results obtained
through the semi-analytical simulation methods is assessed by means of parallel
conventional Monte Carlo simulations, under the assumptions of perfect power
control and perfect channel estimation. The performance results are discussed
in detail, with the help of selected performance bounds. We emphasize that a
moderately large number of BS antennas is enough to closely approximate the
SIMO MFB performance, especially when using the suggested low-complexity
iterative DF technique, which does not require matrix inversion operations. We
also emphasize the achievable "massive MIMO" effects, even for strongly
reduced-complexity linear detection techniques, provided that the number of BS
antennas is much higher than the number of antennas which are jointly employed
in the terminals of the multiple autonomous users.
