Interference cancellation receiver for multiple-access space-time block-coded systems over frequency selective channels

Transmit diversity schemes have emerged in wireless systems as an attractive solution to obtain diversity gains at the mobile terminals. An efficient way of achieving transmit diversity is the use of space-time block-coding (STBC). In high- data rate mobile communication systems with tight reuse configurations, inter-symbol interference (ISI) as well as co-channel interference (CCI) due to user multiple access must be considered in the design of STBC systems. In this work we propose an effective receiver structure for multiple-access space-time block- coded systems capable of performing CCI cancellation and ISI equalization in a two-stage approach. The receiver is based on a cascade connection of i) a multiple-input- multiple-output (MIMO) minimum mean square error (MMSE) spatial filter for CCI cancellation, ii) a modified space-time decoder and iii) a non-linear sequence-detector equalizer for ISI equalization. The non-linear equalizer is a prefiltered delayed decision-feedback sequence estimator (DDFSE). Simulation results demonstrate that the proposed receiver offers remarkable results while being interference-resistant and having a reduced complexity detector.