Interpolation based pilot‐aided channel estimation for STBC spatial modulation and performance analysis under imperfect CSI

Abstract

A combination of space‐time block coding and spatial modulation (STBC‐SM) has been recently proposed for multiple input‐multiple output systems to obtain both spatial diversity gain and more capacity simultaneously while assuming the perfect channel state information (P‐CSI) was available at the receiver. However, in practical scenarios the CSI is unknown to the receiver and should be estimated in order to detect the transmitted data in a reliable way. Therefore, channel estimation (CE) is a major challenge in designing the STBC‐SM systems. In this study, the problem of CE is investigated and a new pilot‐aided channel estimation (PA‐CE) technique, coupled with an interpolation, is proposed for the STBC‐SM systems operating in the presence of rapidly time‐varying mobile channels. Several interpolation schemes such as the linear, nearest neighbour, piecewise cubic Hermite and the low‐pass interpolations are applied and their performances are compared to determine the best suitable interpolation technique to be employed in STBC‐SM systems. Bit error rate (BER) performance of the proposed CE technique is then investigated in time‐varying channels with different modulation. Moreover, the pairwise error probability of the STBC‐SM scheme is derived and its average bit error probability is evaluated analytically in the presence of CE errors.