@conference {ValcarceSPAWC07, title = {Iterative Envelope-Based SNR Estimation for Non-Constant Modulus Constellations}, booktitle = {IEEE Workshop on Signal Processing Advances in Wireless Communications (SPAWC)}, year = {2007}, keywords = {EM, SNR, synchronization}, author = {R. L{\'o}pez-Valcarce and C. Mosquera and Wilfried Gappmair} }