A channel estimation method for MIMO-OFDM Mobile WiMax systems

This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder. Copyright IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.In this paper, channel estimation for Space-Time Block Code (STBC) - Orthogonal Frequency Division Multiplexing (OFDM) is investigated for Mobile WiMax systems. A new channel estimation approach is proposed using the dedicated pilot subcarriers defined at constant intervals by the WiMax standard. The estimation method has low computation as only linear operations are needed due to orthogonal pilot coding. The performances of the proposed method have been demonstrated by extensive computer simulations. For the OFDM system with two transmit antennas and one to four receive antennas and using QPSK modulation, the simulated results under different Stanford University Interim (SUI) channels show that the proposed method has only a 4dB loss compared to the ideal case where the channel is known at the receiver

Well-balanced finite difference WENO schemes for the blood flow model

The blood flow model maintains the steady state solutions, in which the flux gradients are non-zero but exactly balanced by the source term. In this paper, we design high order finite difference weighted non-oscillatory (WENO) schemes to this model with such well-balanced property and at the same time keeping genuine high order accuracy. Rigorous theoretical analysis as well as extensive numerical results all indicate that the resulting schemes verify high order accuracy, maintain the well-balanced property, and keep good resolution for smooth and discontinuous solutions

Efficient space-frequency block coded pilot-aided channel estimation method for multiple-input-multiple-output orthogonal frequency division multiplexing systems over mobile frequency-selective fading channels

© 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.An iterative pilot-aided channel estimation technique for space-frequency block coded (SFBC) multiple-input multiple-output orthogonal frequency division multiplexing systems is proposed. Traditionally, when channel estimation techniques are utilised, the SFBC information signals are decoded one block at a time. In the proposed algorithm, multiple blocks of SFBC information signals are decoded simultaneously. The proposed channel estimation method can thus significantly reduce the amount of time required to decode information signals compared to similar channel estimation methods proposed in the literature. The proposed method is based on the maximum likelihood approach that offers linearity and simplicity of implementation. An expression for the pairwise error probability (PEP) is derived based on the estimated channel. The derived PEP is then used to determine the optimal power allocation for the pilot sequence. The performance of the proposed algorithm is demonstrated in high frequency selective channels, for different number of pilot symbols, using different modulation schemes. The algorithm is also tested under different levels of Doppler shift and for different number of transmit and receive antennas. The results show that the proposed scheme minimises the error margin between slow and high speed receivers compared to similar channel estimation methods in the literature.Peer reviewe

Quasi-orthogonal space-frequency coding in non-coherent cooperative broadband networks

© 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.So far, complex valued orthogonal codes have been used differentially in cooperative broadband networks. These codes however achieve less than unitary code rate when utilized in cooperative networks with more than two relays. Therefore, the main challenge is how to construct unitary rate codes for non-coherent cooperative broadband networks with more than two relays while exploiting the achievable spatial and frequency diversity. In this paper, we extend full rate quasi-orthogonal codes to differential cooperative broadband networks where channel information is unavailable. From this, we propose a generalized differential distributed quasi-orthogonal space-frequency coding (DQSFC) protocol for cooperative broadband networks. Our proposed scheme is able to achieve full rate, and full spatial and frequency diversity in cooperative networks with any number of relays. Through pairwise error probability analysis we show that the diversity gain of our scheme can be improved by appropriate code construction and sub-carrier allocation. Based on this, we derive sufficient conditions for the proposed code structure at the source node and relay nodes to achieve full spatial and frequency diversity.Peer reviewe

A limitation of the hydrostatic reconstruction technique for Shallow Water equations

Because of their capability to preserve steady-states, well-balanced schemes for Shallow Water equations are becoming popular. Among them, the hydrostatic reconstruction proposed in Audusse et al. (2004), coupled with a positive numerical flux, allows to verify important mathematical and physical properties like the positivity of the water height and, thus, to avoid unstabilities when dealing with dry zones. In this note, we prove that this method exhibits an abnormal behavior for some combinations of slope, mesh size and water height.Comment: 7 page

La sculpture antique en ronde bosse découverte en région Provence-Alpes-Côte d' Azur

International audienceIn the region of Provence-Alpes-Côte of Azur, about fifty archaeological sites delivered a important number of ancient sculpture fragments. Most of them are accidental or ancient discoveries, without any archaeological context or any chronological elements allowing to refine the dating of these sculpturesPrès de cinquante sites archéologiques de la région Provence -Alpes-Côte d'Azur ont livré une quantité importante de fragments de sculptures antiques. La plupart sont des découvertes accidentelles ou anciennes, sans contexte archéologique avéré ni éléments chronologiques permettant de les dater précisémen

An analytical solution of Shallow Water system coupled to Exner equation

In this paper, an exact smooth solution for the equations modeling the bedload transport of sediment in Shallow Water is presented. This solution is valid for a large family of sedimentation laws which are widely used in erosion modeling such as the Grass model or those of Meyer-Peter & Muller. One of the main interest of this solution is the derivation of numerical benchmarks to valid the approximation methods

FullSWOF: A free software package for the simulation of shallow water flows

Numerical simulations of flows are required for numerous applications, and are usually carried out using shallow water equations. We describe the FullSWOF software which is based on up-to-date finite volume methods and well-balanced schemes to solve this kind of equations. It consists of a set of open source C++ codes, freely available to the community, easy to use, and open for further development. Several features make FullSWOF particularly suitable for applications in hydrology: small water heights and wet-dry transitions are robustly handled, rainfall and infiltration are incorporated, and data from grid-based digital topographies can be used directly. A detailed mathematical description is given here, and the capabilities of FullSWOF are illustrated based on analytic solutions and datasets of real cases. The codes, available in 1D and 2D versions, have been validated on a large set of benchmark cases, which are available together with the download information and documentation at http://www.univ-orleans.fr/mapmo/soft/FullSWOF/.Comment: 38 page

Utilisation de la norme ISO11179 pour améliorer l'interopérabilité entre les différents schémas de métadonnées pédagogiques

Les actes papiers peuvent être commandés à l'adresse suivant http://www.utc.fr/tice2004/commande_actes_tice2004.docThe IEEE LOM is now standardized since July 2002 but it is not the only one standard used to describe learning objects. Application profiles based on the LOMand other educational metadata schemas coexist. This established fact leads to a lack of interoperability between descriptions based on different schemas. To solve this problem, we propose a solution based on the ISO 11179 standard, allowing the description of a conceptual level independently of any particular representation. Thus, each educational metadata schema can be specified as an “instantiation” of a unique educational conceptual level linking them.Depuis Juillet 2002, le LOM est devenu un standard de l'IEEE, mais ce n'est pas le seul schéma de métadonnées pédagogiques existant. En effet, d'autres schémas totalement indépendants sont aussi utilisés, et depuis quelques mois de nombreux schémas issus du LOM apparaissent : on les nomme des profils d'applications du LOM. Or en les étudiant, on en déduit que l'interopérabilité entre ces schémas n'est plus automatique. Pour résoudre ce problème, nous proposons d'utiliser une méthode définie par la norme ISO11179 qui permet de dissocier l'aspect conceptuel de l'aspect représentation lors de la conception de schéma de métadonnées. Ainsi, grâce à ce modèle, les schémas de description de documents pédagogiques pourraient être considérés comme des instanciations d'un seul et unique modèle conceptuel, et donc devenir interopérables