Overcoming the inter-symbol interference (ISI) and co-channel interference (CCI) encountered in broadband frequency-selective multi-user multi-input multi-output (MU-MIMO) wireless channels with advanced baseband signal processing techniques is the focus of the thesis. Single-carrier (SC) techniques with frequency domain equalization (FDE) are considered as they benefit from much reduced peak-to-average transmit power ratio (PAPR) and hence considerably less linearity requirements on the radio frequency amplifier as compared to orthogonal frequency division multiplexing (OFDM) methods. A new two-step interference cancellation scheme is first proposed for the uplink MU-MIMO wireless channel. SC transmission is exploited together with time-reversed spacetime block coding. Average symbol error rate simulations for quasi-static and fast-fading broadband frequency-selective two-user MIMO channels confirm the utility of the approach.