Abstract: Single channel mixed signal parameter estimation is a hot topic in wireless communication and signal processing. In this paper, two cyclic auto-correlation based time estimation methods are presented for single-channel mixed communication signals, which is based on the relationship of cyclic autocorrelation functions and signal’s modulation parameters. The two different methods are designed for scenarios of unknown and known channels of both signals respectively. The methods treat both co-channel signals as desired signals. Firstly, cyclic autocorrelation function of the received mixed signal is analyzed, and then the linear equations on time delay parameters are established for the two scenarios. Secondly, the closed-form solution for time delay parameters of both co-channel signals is obtained by solving the equations, and two estimation algorithms are presented. The Cramer-Rao bound is also analyzed in this paper. Finally, computer simulation results are provided to demonstrate the performance of the proposed methods and their application conditions.