Low complexity turbo receiver for multi-user STBC block transmission systems

Low complexity space-frequency turbo detection and decoding schemes are proposed for multi-user space-time block-coded (STBC) block transmission systems, including cyclic prefix based single-carrier block transmission (CP-SCBT) system and OFDM system. Using the algebraic properties of these systems, we give the implementation of MMSE- and match-filter-based (MF) turbo detector in the frequency domain. The detector complexity is independent of the channel memory and of the constellation size. To further reduce the complexity, a switched MMSE/MF detector is applied to the turbo receivers. Simulation results show that in the mobile frequency selective channels the performance of the proposed receivers is comparable to the near optimal list sphere decoding based turbo receiver, and it is very close to that of the single-user in the Gaussian channel