Optimal sounding signal design based on MMSE criterion in OFDM system

We focus on sounding signal design for single-input single-output. It is shown analytically that the optimum sounding signal for the time static case, f_dT = 0, is one whose frequency spectrum has constant magnitude across the band. Equivalently the autocorrelation of the sounding signal should be an impulse. Simulation results show that the optimum sounding signal outperforms the random sounding signals.