SNR estimation of QAM-modulated transmissions over time-varying SIMO channels

We propose a new technique to estimate the signal-to-noise ratio (SNR) over flat fading time-varying single-input multiple-output (SIMO) channels, for quadrature amplitude modulation (QAM) signals in complex additive white Gaussian noise (AWGN). This technique relies on the use of periodically transmitted pilot symbols in the estimation process. It is a decision directed (DD) procedure since detected data symbols are also used. Performance is assessed via Monte Carlo simulations. Using the normalized root mean square error (NRMSE) as a measure of performance, our new estimator performs well over a wide SNR range.