NDA SNR estimation techniques for non-equiprobable signaling using non-coherent OOK receivers

In this paper, non-data aided (NDA) signal-to-noise ratio (SNR) estimation techniques for non-coherent on-off keying (OOK) receivers using non-equiprobable signal transmission is analyzed. Expectation-maximization (EM), M
₁
M
₂
and M
₂
M
₃
estimators are investigated. It is shown that the performance of moments based estimators degrade in high SNR region due to bad noise estimates. Moreover, lower moment based estimator, i.e., M
₁
M
₂
is shown to be inoperable for equiprobable case. EM estimator is investigated and a noise recalibration stage is added for high SNR region. Hybrid estimators, i.e., M
₁
M
₂
-EM and M
₂
M
₃
- EM are proposed to cover a wide range of SNR for equiprobable and non-equiprobable signal transmission. The normalized mean square error (NMSE) is evaluated for each estimator. Closed form analytical expressions are derived for each of the estimators and is found to be in good agreement with the simulations.