CM-based channel estimators for space-time block-coded M-PSK and M-QAM systems

A constant modulus (CM)-based channel estimation scheme for space-time block-coded M-PSK and M-QAM transmission systems is derived. Exploiting the orthogonal structure of the space-time block coded transmission model, the analytical solutions to minimize the CM cost function are given for 2/sup k/ PSK (k>2) and 2/sup 2k/-QAM schemes, and used to derive the expressions for the CM-based channel estimators. Illustrative results on the performance are presented.