Optimal Power Allocation and Design of Pilot Symbols for Frequency-Selective Correlated MIMO Channel Estimation

This paper treats the optimal design, placement and power allocation of pilot symbols for frequency-selective correlated multiple-input multiple-output (MIMO) channel estimation. We extend the correlated MIMO channel model in terms of virtual channel representation proposed by Sayeed to the frequency-selective case. We show that the principle of the optimal design and placement of pilot symbols proposed by Dong and Tong can be applied to the correlated MIMO channel. On top of that, optimal power allocation of pilot symbols constrained by total pilot symbol power is presented so that the minimum Cramer-Rao lower bound can be achieved. In general, the closed-form of optimal power allocation of pilot symbols does not exist. However, in case of high tap-to-noise ratio, an approximate closed-form of power allocation scheme is derived