Abdelaziz Samet

DOA Estimation of Temporally and Spatially Correlated Narrowband Noncircular Sources in Spatially Correlated White Noise

The main contribution of our work consists in developing for the first time a method of estimating the direction of arrival (DOA) parameters assuming noncircular and temporally and spatially correlated signals. This new approach, based on a significant enhancement of the two-sided instrumental variable signal subspace fitting (IV-SSF) method, outperforms its classical version in terms of lower bias and error variance. Moreover, it will be shown that our new method is statistically more efficient than the MODE method especially in the case of partly and fully coherent signals where only the extended and the classical two-sided IV-SSF methods are applicable. We also derive an explicit expression for the stochastic Cramér-Rao bound (CRB) of the DOA estimates from temporally and spatially correlated signals generated from noncircular sources. The new CRB is compared to those of circular temporally correlated and noncircular independent and identically distributed signals to show that the CRB obtained assuming both noncircular sources and temporally correlated signals is lower than the CRBs derived considering only one of these two assumptions. This illustrates the potential gain that both noncircularity and temporal correlation provide when considered together. It will also be proven that the difference between the three CRBs increases with the number of snapshots. However, as the signal-to-noise ratio (SNR) increases, the CRBs merge together and decrease linearly. Moreover, at low SNR values it will be shown that temporal correlation is more informative about the unknown DOA parameters than noncircularity. Finally, the CRB derived assuming noncircular and temporally correlated signals depends on the noncircularity rate, the circularity phase separation, and the DOA separation.

Effects of metal plate to RFID tag antenna parameters

In this paper, the effects of a metal plate to antenna parameters (input impedance, return loss and radiation patterns) is presented when the RFID tag antenna is horizontally placed near the metal plate. The metal plate has finite size and rectangular shape. The new technique based on the moment method and RWG basis functions developed by Ghannay et al. has been used to simulate the dependency of antenna parameters on the size of the plate and the distance between the antenna and the plate.

Ricean K-Factor and SNR Estimation for M-PSK Modulated Signals Using the Fourth-Order Cross-Moments Matrix

In wireless communication systems, the Ricean K-factor estimation is required in several applications such as link budget calculations. While the SNR estimation can be used to measure the link quality. In this paper, the Ricean K-factor estimation for M-ary Phase Shift Keying (M-PSK) modulated signals with additive noise is studied. To this end, the Fourth-Order Cross-Moments (FOCM) of the received signal are considered. First, the Signal-to-Noise Ratio (SNR) is computed by estimating the powers of the desired components of the signal and the noise. Then, the K-factor is estimated using the kurtosis of the Ricean channel. Simulation results show that our approach outperforms the most recent developed estimator in the literature.

Joint Estimation of the Ricean K-Factor and the SNR for SIMO Systems Using Higher Order Statistics

Abstract-In this paper, we propose a joint estimator of the Ricean K-factor and the signal-to-noise ratio (SNR) for singleinput multiple-output (SIMO) systems. The second-order moment and the fourth-order cross-moment matrix of the received signal envelope are used to estimate the desired parameters. The K-factor is estimated using the kurtosis of the Ricean channel gain while the SNR is obtained by separately estimating the powers of the useful signal and the additive noise. Two versions are developed depending on the value of the kurtosis of the transmitted data. Unlike the autocorrelation-based K-factor and SNR joint estimator developed in [1] that is tailored for unmodulated signals, the proposed method applies to any digital modulation and does not request the knowledge of the maximum Doppler spread. Simulation results are included to illustrate the performance behavior of the new estimator.

A new importance-sampling ML estimator of time delays and angles of arrival in multipath environments

In this paper, the importance sampling (IS) concept is exploited for the first time in the context of maximum likelihood (ML) estimation of both the time delays and angles of arrival (AoAs) in multipath propagation environments. The global maximum of the compressed likelihood function (CLF) is found empirically with a low computational cost. Simulations suggest that the new IS-based ML-type estimator outperforms, in terms of accuracy, the main state-of-the-art techniques published on the topic. It is also able to reach the Cramér-Rao-lower bound (CRLB) [13] with few received samples.

On the benefits of repeated game models for green cross-layer power control in small cells

In this paper, we consider the problem of distributed power control for multiple access channels when energy-efficiency has to be optimized. In contrast with related works, the presence of a queue at each transmitter is accounted for and globally efficient solutions are sought. To this end, a repeated game model is exploited and shown to lead to solutions which are distributed in the sense of the decision, perform well globally, and may rely on limited channel state information at the transmitter.

Nonlinear complex LS-SVM for highly selective OFDM channel with impulse noise

In this contribution, channel estimation for OFDM system in high mobility environment with the presence of Gaussian and non-Gaussian impulse noise with different ranges interfering with reference signals is faced. The estimation of the frequency selective time varying multipath fading channel is performed by using a nonlinear channel estimator based on a complex Least Squares Support Vector Machine (LS-SVM) which is developed and applied to Long Term Evolution (LTE) downlink. The estimation algorithm makes use of the pilot signals to estimate the total frequency response of the frequency selective multipath channel. Thus, the algorithm maps trained data into a high dimensional feature space (possibly infinity) and uses the structural risk minimization (SRM) principle to carry out the regression estimation for the frequency response function of the fading channel. The obtained results confirm the effectiveness of the proposed approach which outperforms the conventional LS and Decision Feedback methods to track the fading channel variations.

Direction of arrival estimation for nonuniform linear antenna

This paper deals with the problem of the Direction Of Arrival (DOA) estimation with nonuniform linear arrays (NLA). We show that the Root-MUSIC algorithm can be directly applied in the case of the non uniform array. Moreover, we show that the elimination of a certain sensors of a uniform array degrades only very slightly the performance thanks to the use of the high-resolution(HR) methods like Root-MUSIC. We also show that root-MUSIC presents good performances, and does not require any additional data transformation. In addition, an analytical expression from the estimator variance are derived in order to support our simulation results and to show the advantages of the NLA.

A new low-complexity angular spread estimator in the presence of line-of-sight with angular distribution selection

This article treats the problem of angular spread (AS) estimation at a base station of a macro-cellular system when a line-of-sight (LOS) is potentially present. The new low-complexity AS estimator first estimates the LOS component with a moment-based K-factor estimator. Then, it uses a look-up table (LUT) approach to estimate the mean angle of arrival (AoA) and AS. Provided that the antenna geometry allows it, the new algorithm can also benefit from a new procedure that selects the angular distribution of the received signal from a set of possible candidates. For this purpose, a nonlinear antenna configuration is required. When the angular distribution is known, any antenna structure could be used a priori; hence, we opt in this case for the simple uniform linear array (ULA). We also compare the new estimator with other low-complexity estimators, first with Spread Root-MUSIC, after we extend its applicability to nonlinear antenna array structures, then, with a recently proposed two-stage algorithm. The new AS estimator is shown, via simulations, to exhibit lower estimation error for the mean AoA and AS estimation.

E-Shaped Patch Antenna modeling with MoM and RWG basis functions

In this paper, we put the emphasis on the analysis and modeling of an E-Shaped Patch Antenna for wireless communications. This antenna can be designed to provide an Ultra Wide Bandwidth. The Method of Moment is utilized for the analysis. We use the Mixed Potential Integral Equation (MPIE) in conjunction with the Rao, Wilton and Glisson triangular discretization (RWG basis functions). A comprehensive parametric study has been carried out to understand the effects of various dimensional parameters and to optimize the performance of the antenna.