Title :
SNR estimation in time-varying fading channels
Author :
Wiesel, Ami ; Goldberg, Jason ; Messer-Yaron, Hagit
Author_Institution :
Dept. of Electr. Eng.-Syst., Univ. of Tel Aviv, Israel
fDate :
5/1/2006 12:00:00 AM
Abstract :
Signal-to-noise ratio (SNR) estimation is considered for phase-shift keying communication systems in time-varying fading channels. Both data-aided (DA) estimation and nondata-aided (NDA) estimation are addressed. The time-varying fading channel is modeled as a polynomial-in-time. Inherent estimation accuracy limitations are examined via the Cramer-Rao lower bound, where it is shown that the effect of the channel´s time variation on SNR estimation is negligible. A novel maximum-likelihood (ML) SNR estimator is derived for the time-varying channel model. In DA scenarios, where the estimator has a simple closed-form solution, the exact performance is evaluated both with correct and incorrect (i.e., mismatched) polynomial order. In NDA estimation, the unknown data symbols are modeled as random, and the marginal likelihood is used. The expectation-maximization algorithm is proposed to iteratively maximize this likelihood function. Simulation results show that the resulting estimator offers statistical efficiency over a wider range of scenarios than previously published methods.
Keywords :
channel estimation; expectation-maximisation algorithm; fading channels; phase shift keying; polynomials; time-varying channels; Cramer-Rao lower bound; SNR estimation; expectation-maximization algorithm; maximum-likelihood estimator; nondata-aided estimation; phase-shift keying communication systems; polynomial-in-time; signal-to-noise ratio; time-varying fading channels; Closed-form solution; Expectation-maximization algorithms; Fading; Maximum likelihood estimation; Phase estimation; Phase shift keying; Polynomials; Signal to noise ratio; Time varying systems; Time-varying channels; Cramer–Rao bound (CRB); expectation-maximization (EM); maximum-likelihood (ML) estimation; signal-to-noise ratio (SNR);
Journal_Title :
Communications, IEEE Transactions on
DOI :
10.1109/TCOMM.2006.873995