Blind SNR estimation with empirical characteristic function’s derivative in high-order modulation system

In order to retrieve the pre-estimated information from the received signals, it is necessary to estimate the variance of AWGN channel during the initialization of Turbo iterative decoder. Some literature has been devoted to this problem in BPSK/8PSK scenarios, and in this paper, we present another low-complexity blind SNR estimation method based on empirical characteristic functionpsilas derivative. It proves to be effective for both MPSK and MQAM, which alternatively provides a good un-biased estimation at receiver even without the knowledge of modulation type, as we can see in the simulations.