Single-channel mixed signal detection based on signal noise ratio estimation

It is difficult to distinguish the mixed signal received by the single channel receiver from single signal simply based on the waveforms and the spectrum features. In this paper, the expression on the observed and the valid signal-to-noise ratio (SNR) of single-channel mixed signal is derived and compared with that of single signal(just one signal component). We find that the observed and the valid SNR of single signal are identical, but for the mixed signal, the observed SNR is significantly greater than valid SNR. An appropriate threshold is set under the condition of minimum the single signal leaking-detecting probability to obtain best detection performance. Numerical results show that for both symmetric and asymmetric mixed signal, the proposed algorithm performs well without timing recovery, thus making proposed algorithm more practical.