Open Access

Blind Estimation of the Phase and Carrier Frequency Offsets for LDPC-Coded Systems

EURASIP Journal on Advances in Signal Processing20102010:293572

Received: 2 September 2010

Accepted: 24 November 2010

Published: 1 December 2010


We consider in this paper the problem of phase offset and Carrier Frequency Offset (CFO) estimation for Low-Density Parity-Check (LDPC) coded systems. We propose new blind estimation techniques based on the calculation and minimization of functions of the Log-Likelihood Ratios (LLR) of the syndrome elements obtained according to the parity check matrix of the error-correcting code. In the first part of this paper, we consider phase offset estimation for a Binary Phase Shift Keying (BPSK) modulation and propose a novel estimation technique. Simulation results show that the proposed method is very effective and outperforms many existing algorithms. Then, we modify the estimation criterion so that it can work for higher-order modulations. One interesting feature of the proposed algorithm when applied to high-order modulations is that the phase offset of the channel can be blindly estimated without any ambiguity. In the second part of the paper, we consider the problem of CFO estimation and propose estimation techniques that are based on the same concept as the ones presented for the phase offset estimation. The Mean Squared Error (MSE) and Bit Error Rate (BER) curves show the efficiency of the proposed estimation techniques.

Publisher note

To access the full article, please see PDF.

Authors’ Affiliations

Alcatel-Lucent Bell Labs, INRIA
Institut Télécom, Télécom Bretagne, Université Européenne de Bretagne
School of Electronic and Electrical Engineering, University of Leeds
International University of Rabat


© Rodrigue Imad et al. 2010

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.