Accurate BER Analysis of Orthogonal Space-Time Block Codes with MMSE Channel Estimation

Abstract

In this paper, we investigate the effect of imperfect channel estimation on the bit error rate (BER) performance of orthogonal space-time block codes (OSTBCs). The multiple-input multiple-output (MIMO) propagation channel is assumed to be affected by uncorrelated flat Rayleigh block fading. We consider a mismatched maximum-likelihood (ML) receiver, which estimates the channel matrix from known pilot symbols according to a minimum mean-square error (MMSE) criterion, and uses the channel estimate in the symbol-by-symbol detection algorithm as if it were the true channel matrix. For both PAM and QAM constellations and OSTBCs satisfying a proposed criterion, we present simple exact closed-form expressions for the BER of the mismatched receiver and the corresponding BER degradation as compared to a receiver that knows the true channel matrix. For OSTBCs that do not satisfy this criterion, a simple approximation of the BER and the associated BER degradation is derived, assuming PAM and QAM constellations. By means of computer simulations, this approximation is shown to be very accurate. I. INTRODUCTION