Optimal pilot symbol design for spatially correlated MIMO-OFDM channels

This paper addresses the optimal transmitted pilot signal design for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems under spatially correlated frequency-selective fading channels. With the aid of the optimization theory framework, we develop the optimal pilot symbols and obtain the optimal placement of pilot tones with respect to the mean square error of the linear channel estimate. In addition, using the majorization theory, we derive the optimal power allocation for pilot symbols subject to the power allocated for training.