43 research outputs found
Blind frame synchronisation for Block code
No full textPublication in the conference proceedings of EUSIPCO, Florence, Italy, 200
Blind source separation of a mixture of communication sources emitting at various baud-rates
No full text
TRANSMIT DIVERSITY OVER FREQUENCY-SELECTIVE FADING CHANNEL : A BLIND APPROACH
No full textPublication in the conference proceedings of EUSIPCO, Viena, Austria, 200
On Carrier QPSK Signal Detector Based on Second Order Cyclic-Moments
No full textInternational audienceThis paper considers the problem of detecting a QPSK communication signal on carrier. We propose a method to perform the detection thanks to second order cyclostationarity theory. It is well known that for such a signal, there is no cyclic frequency multiple of the studied signal carrier frequency. Hence, the basic method of second order cyclic-moments energy measurement is unable to detect any energy directly linked to the signal carrier. In this article, we propose a novel criterion based on second order cyclic-moments that exploits the convergence speed of the cyclic autocorrelation function estimator. We show that for a modulated QPSK signal the cyclic-correlation converges to zero but not in the same way if the cyclic frequency is a multiple of the carrier frequency or not. We develop a statistical test and derive the asymptotic probability density function of the criterion to propose a detection threshold. System performance simulation results are then evaluated by Monte Carlo simulations and compared to the results of fourth order nonlinear transformation method
Carrier phase recovery of LDPC-coded systems based on the likelihood difference algorithm
No full textInternational audienceThe problem of blind phase offset recovery of low density parity-check (LDPC)-coded systems is considered in this paper. We propose a new algorithm of phase offset estimation that involves the computation and maximization of a likelihood difference (LD)-based cost function calculated from the parity-check matrix of the code. We show in this paper that the new cost function has a simplified form compared to another algorithm proposed in the literature and presents similar estimation performance. Mean squared error (MSE) curves show very good performance of the proposed phase offset estimation algorithm, even at low signal-to-noise ratios
Estimation of the symbol period: the frequency offset case
No full textWe address the blind equalization of a telecommunica-tion signal, the characteristics of which are totally un-known (channel, symbol period, alphabet of the sym-bols, frequency offset). In [1] was proposed a method-ology originating from deconvolution ideas, for jointly estimating the symbol period and the emitted symbols. In this contribution, we show that the presence of a fre-quency offset does not alter this approach. Simulation results illustrate the robustness of the Ts estimate with respect to the frequency offset. 1 Introduction an
Blind Estimation of the Phase and Carrier Frequency Offsets for LDPC-Coded Systems
No full textAbstract 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.</p
