A combined receiver for unitary space-time modulation

In this paper, a combined receiver for unitary space-time modulation (USTM) system is proposed, which combines the noncoherent detector and coherent detector for USTM constellations, thus called “combined receiver”. The output of the conventional noncoherent detector for USTM system is utilized to derive the channel measurement components which is then used to estimate the channel state information (CSI) using a Wiener filter based on minimum mean-square error (MMSE), and finally a coherent detector is employed. In our scheme, we can obtain not only the past and the present channel measurement components, but also the future ones, which are all used to estimate the CSI, resulting in a more refined channel estimation. Simulation results show the good performance of the proposed combined receiver compared with the previously proposed generalized quadratic receivers (GQRs).