In control engineering, system identification is frequently used to create models from inputoutput data. The MPC is a very well-known control strategy because of its capacity to deal with a system’s limitations. MPC determines the optimal input based on optimization. The optimization for each time step needs to be achieved in less time than the sampling time of the system. In this paper, the optimal signal design in system identification for MPC is presented. The reference signal has derived from the input perturbation signal in both time domain and frequency domain. An equation has derived to determine the relationship between the input signal and the reference signal. Three dissimilar amplitude spectra, namely flat spectrum signal i...