Miloud Frikel

Bearing detection of noised wideband sources for geolocation

In this paper, we propose a method for the localisation of wideband sources in order to locate mobile station. Indeed, directions-of-arrival of wideband sources are estimated by coherent subspace methods, which use the focusing operators, in the presence of a correlated noise and, then, the angulation is used to determine the mobiles position. Practical methods of the estimation of the coherent signal subspace are given and are compared for mobile system location

Traitement d’antenne large bande : Opérateurs de focalisation

Since many years, many methods have been proposed to wideband signals. These methods use the coherent signal subspace. Several focusing operators have been developed. In this paper we study the spectral matrix eigenvector operators. Improved operators are proposed which reduce the computer time. In order to do that, we use the focalisation operators obtained from the signal subspaces estimated at each analysis frequency. A new focusing operator is presented which uses directly the received data. Results of computer simulations are included to support our analysis.RésuméAu cours de ces dernières années, plusieurs méthodes de traitement des signaux à large bande ont été proposées. Ces méthodes sont basées essentiellement sur la technique de focalisation. Divers opérateurs de focalisation ont été développés. Dans cette étude, les opérateurs utilisent des vecteurs propres des matrices interspectrales. Des améliorations de ces opérateurs conduisent à des réductions de temps de calcul importantes. Ces améliorations sont basées sur l’utilisation des sous-espaces signaux estimés aux différentes fréquences d’analyse. Un nouvel opérateur de focalisation utilisant directement les vecteurs des signaux reçus est présenté ainsi que des résultats obtenus sur des signaux simulés.Au cours de ces dernieres annees, plusieurs methodes de traitement des signaux a large bande ont ete proposees. Ces methodes sont basees essentiellement sur la technique de focalisation. Divers operateurs de focalisation ont ete developpes. Dans cette etude, les operateurs utilisent des vecteurs propres des matrices interspectrales. Des ameliorations de ces operateurs conduisent a des reductions de temps de calcul importantes. Ces ameliorations sont basees sur l’utilisation des sous-espaces signaux estimes aux differentes frequences d’analyse. Un nouvel operateur de focalisation utilisant directement les vecteurs des signaux recus est presente ainsi que des resultats obtenus sur des signaux simules.

BER analysis of parallel and successive interference cancellation employing MMSE equalizer for MC-CDMA systems

This paper introduces a parallel/sucessive interference cancellation scheme for multi-carriers code-division multiple access (MC-COMA) in the case of a downlink transmission, that reduces the degrading effect on the desired user of interference from the other users who share the same channel. The implementation complexity of the scheme is linear in the number of users and operates on the fact that parallel processing simultaneously removes from each user a part of the interference produced by the remaining users accessing the channel the amount being proportional to their reliability. The parallel processing can be done in multiple stages. The proposed scheme uses an hybrid interference cancellation combining the advantages of these two schemes: parallel interference cancellation (PIC) and successive interference cancellation (SIC). The hybrid scheme (S-PIC) is faster, reliable and it reduces the computational load. Simulation results are given for different scenarios.

Identification and equalization of MC-CDMA system driven by stochastic chaotic code

In this contribution, we consider the problem of blind identification of Finite Impulse Response (FIR) system driven by a stochastic chaotic signal. Because of the inherently deterministic nature of a chaotic signal, we initialize the recursive equation which define the chaotic signal, by a random number, this leads to a random excitation. It was observed that the equalization performance of the chaotic approach was superior to the conventional statistical method. This is another benefit for using chaos in a spread spectrum communication system.

Observer Design for Time Delay Nonlinear Triangular Systems

Abstract In this work an observer for a class of delayed nonlinear triangular systems with multiple and simple time-delay is proposed. The main feature of this observer is that it is easy to implement because of its constant gain. First, the observer synthesis is presented for nonlinear systems with variable time-delay and is extended for nonlinear systems with multiple time-delay. The observer performance is evaluated through numerical simulations.

A Numerical Analysis of Double-Aperture Interferences

This paper treats the problem of diffraction of monochromatic field by two apertures under the conditions of normal incidence and linear polarization. We study the effect of diffraction and interferences by two thin apertures in the Fraunhofer region using Gauss approximation, where we introduce a birefringent wedge whose length is equal to the width of single aperture, we demonstrate the effect of the wedges thickness on the intereference pattern.

Blind equalisation in the presence of bounded noise

This study addresses the blind equalisation problem in the presence of bounded noise using an optimal bounding ellipsoid algorithm. This provides an adequate blind equalisation algorithm with an accurate parameter estimation. A fundamental analysis of the involved equaliser is performed to emphasise its underlying properties. This fundamental result is corroborated by promising simulation results.

MC-CDMA System Identification and Equalization Using the LMS Algorithm and Takagi-Sugeno Fuzzy System

Abstract In this paper we are focused on the Multi-Carrier Code Division Multiple Access (MC-CDMA) equalization problem. The equalization is performed using the Minimum Mean Square Error (MMSE) and Zero Forcing (ZF) equalizer based on the identified parameters representing the indoor scenario (European Telecommunications Standards Institute Broadband Radio Access Networks (ETSI BRAN A) channel model), and outdoor scenario (ETSI BRAN E channel model). These channels are normalized for fourth-generation mobile communication systems. However, for such high-speed data transmissions, the channel is severely frequency-selective due to the presence of many interfering paths with different time delays. The identification problem is performed using the Least Mean Squares (LMS) algorithm and the Takagi-Sugueno (TS) fuzzy system. The comparison between these techniques, for the channel identification, will be made for different Signal to Noise Ratios (SNR).

Identification of Broadband Radio Access Network using the Takagui-Sugeno fuzzy systems and Higher Order Statistics

In this paper, we consider the problem of selective radio channel identification. Two technics are used, the first one is based on Higher Order Statistics (HOS), the second is based on Takagui-Sugeno (TS) fuzzy systems. In order to evaluate the proposed algorithms, we have used two practical selective frequency fading channels called Broadband Radio Access Network (BRAN A and BRAN E) normalized for MC-CDMA systems are considered to perform the proposed technics. The simulation results, for different Signal to Noise Ratio (SNR), demonstrates that: the algorithm based on Higher Order Statistics (HOS) is more efficiency than the TS algorithms in noisy environment - smallest SNR- but the TS algorithm more efficient than the HOS algorithms for highest SNR values.