Blind l1-norm-based phase estimation for cross-QAM robust to finite precision effects

We introduce a new blind criterion for carrier phase recovery of QAM modulated data, based on the maximization of the average of the q-th power of the phase-compensated received data vector `1-norm. In order to improve the performance of state-of-the-art higher-order estimators for cross-QAM constellations, which are sensitive to finite precision effects, our focus is on low-order methods (q = 1 and 2). Fixedpoint iterations with good local convergence properties are given for these cases; different existing phase estimators can be used as initializers, depending on the operation environment and application constraints. A variance analysis of the novel estimators is derived, which shows that they are competitive against higher-order estimators. More importantly, Monte Carlo simulations show that the novel schemes remain robust to quantization effects and finite precision implementation, and thus they constitute an attractive choice in realistic scenarios. Index Terms Carrier offset, cross-QAM constellations, blind phase estimation, fixed point implementation. ∗ Corresponding author. M. Álvarez-Dı́az and R. López-Valcarce are with the Department of Signal Theory and Communications, University of Vigo, 36310 Vigo, Spain (e-mail: {malvarez,valcarce}@gts.tsc.uvigo.es). I. Gómez Alonso is with the Galician Research and Development Center in Advanced Telecommunication (GRADIANT), ETSI Telecomunicación, 36310 Vigo, Spain (email: [email protected]). This work was supported by the European Commission through the IST Programme under Contract IST-027393 SatNExII and by the Spanish Government under projects SPROACTIVE (ref. TEC2007-68094-C02-01/TCM) and COMONSENS (CONSOLIDER-INGENIO 2010 CSD2008-00010). Parts of this paper were presented at the 13th IEEE Workshop on Statistical Signal Processing (SSP 2005), Bourdeaux, France, July 2005. March 15, 2009 DRAFT