  This letter investigates the problem of blind detection of orthogonal
space-time block codes (OSTBC) over a quasi-static flat multiple-input
multiple-output (MIMO) Rayleigh fading channel. We first introduce a core
iterative least-squares (ILS) algorithm to blindly detect OSTBC signals without
the knowledge of channel state information (SCI) at the receiver. This ILS
algorithm has low computational complexity but may converge to local optimum
which offers unreliable detection result. Then, in order to improve the
detection performance, we propose an enhanced ILS (E-ILS) approach which is
based on statistical analysis of repeated independent ILS procedures on
received data. Extensive simulation studies prove the efficiency of the
proposed E-ILS algorithm with blind detection performance approaching the
optimal maximum-likelihood detector with known CSI.
