Space-time turbo equalization scheme with beam steering based on SVD and QRD over frequency selective fading MIMO channels

Abstract

To support broadband multiple-input multiple-output (MIMO) systems using a single carrier transmission scheme under frequency selective fading conditions, this paper proposes a new space-time turbo equalization scheme that employs a beam steering technique based on singular value decomposition (SVD) and QR decomposition (QRD) which are employed to suppress mutual interference between eigenbeams called interbeam interference (IBI). In addition, soft interference cancellation followed by a minimum mean square error filtering (SC/MMSE) type turbo equalizer is applied to each eigenbeam signal sequence to suppress co-beam interference (CBI) defined as intersymbol interference (ISI) on the co-eigenbeam, as well as the residual IBI. Computer simulation confirms that the proposed scheme is effective in improving spectral efficiency without extra bandwidth with low transmit power.