Blind signal-to-noise-ratio estimation for a constant envelope MIMO MC-CDMA system using cyclic delay diversity

Data aided signal space projection based signal-to-interference plus noise-ratio (SINR) estimators have been previously proposed for time-division-multiple-access (TDMA) cellular systems and are well known for their excellent performance and computational simplicity. This paper presents a blind signal projection (SP) based SNR estimator for a constant envelope multicarrier code division multiple access (MC-CDMA) system that uses cyclic delay diversity (CDD) and operates on a time varying frequency selective fading channel. Because the orthogonal spreading sequences form the basis of the signal space, a training sequence or data decisions are not needed and orthonormalization is not required. Thus, the proposed SNR estimator is computationally efficient and very accurate estimates are achieved without sacrificing power and bandwidth.