Statistical Precoding with Decision Feedback Equalization over a Correlated MIMO Channel

in IEEE Transactions on Signal Processing (2010), 58(12), 6298-6311

The decision feedback (DF) transceiver, combining linear precoding and DF equalization, can establish point-to-point communication over a wireless multiple-input multiple-output channel. Matching the DF ... [more ▼]

The decision feedback (DF) transceiver, combining linear precoding and DF equalization, can establish point-to-point communication over a wireless multiple-input multiple-output channel. Matching the DF-transceiver design parameters to the channel characteristics can improve system performance, but requires channel knowledge. We consider the fast-fading channel scenario, with a receiver capable of tracking the channel-state variations accurately, while the transmitter only has long-term, channel-distribution information. The receiver design problem given channel-state information is well studied in the literature. We focus on transmitter optimization, which amounts to designing a statistical precoder to assist the channel-tailored DF equalizer. We develop a design framework that encompasses a wide range of performance metrics. Common cost functions for precoder optimization are analyzed, thereby identifying a structure of typical cost functions. Transmitter design is approached for typical cost functions in general, and we derive a precoder design formulation as a convex optimization problem. Two important subclasses of cost functions are considered in more detail. First, we explore a symmetry of DF transceivers with a uniform subchannel rate allocation, and derive a simplified convex optimization problem, which can be efficiently solved even as system dimensions grow. Second, we explore the tractability of a certain class of mean square error based cost functions, and solve the transmitter design problem with a simple algorithm that identifies the convex hull of a set of points in R2. The behavior of DF transceivers with optimal precoders is investigated by numerical means. [less ▲]

Market structure, screening activity and bank lending behaviour

E-print/Working paper (2010)

In this paper we construct a theoretical model of spatial banking competition that considers the differential information among banks and potential borrowers in order to investigate how market structure ... [more ▼]

In this paper we construct a theoretical model of spatial banking competition that considers the differential information among banks and potential borrowers in order to investigate how market structure affects the lending behavior of banks and their incentives to invest in screening technology. Consistent with the prevailing view in the relevant literature, our results reveal that competition reduces lending cost, which, in turn, encourages the entry of new customers in the loan market. Also, that the transportation cost that potential borrowers have to pay in order to reach the bank of their interest is decreased with the degree of competitiveness. Importantly, we demonstrate that market structure exerts a considerable positive effect on banks’ incentives to screen their loan applicants since banks are found to invest more in screening as competition in the market becomes higher. This is to say, banks resort to screening that serves as a buffer mechanism against bad credit which entails higher risk and which is more likely under competitive conditions. Overall, our findings provide support to a rather close link between the degree of competition, bank lending activity, and the investment of banks in screening technology. [less ▲]

Le médium nomade du logogramme et du logoneige de Christian Dotremont

in Revue Proteus. Cahiers des théories de l'art (2010), 1

Quasi-polynomial functions over bounded distributive lattices

in Aequationes Mathematicae (2010), 80(3), 319-334

In [6] the authors introduced the notion of quasi-polynomial function as being a mapping $f\colon X^n\to X$ defined and valued on a bounded chain $X$ and which can be factorized as $f(x_1,\ldots,x_n)=p ... [more ▼]

In [6] the authors introduced the notion of quasi-polynomial function as being a mapping $f\colon X^n\to X$ defined and valued on a bounded chain $X$ and which can be factorized as $f(x_1,\ldots,x_n)=p(\varphi(x_1),\ldots,\varphi(x_n))$, where $p$ is a polynomial function (i.e., a combination of variables and constants using the chain operations $\wedge$ and $\vee$) and $\varphi$ is an order-preserving map. In the current paper we study this notion in the more general setting where the underlying domain and codomain sets are, possibly different, bounded distributive lattices, and where the inner function is not necessarily order-preserving. These functions appear naturally within the scope of decision making under uncertainty since, as shown in this paper, they subsume overall preference functionals associated with Sugeno integrals whose variables are transformed by a given utility function. To axiomatize the class of quasi-polynomial functions, we propose several generalizations of well-established properties in aggregation theory, as well as show that some of the characterizations given in [6] still hold in this general setting. Moreover, we investigate the so-called transformed polynomial functions (essentially, compositions of unary mappings with polynomial functions) and show that, under certain conditions, they reduce to quasi-polynomial functions. [less ▲]

Leverage and Risk in US Commercial Banking in the Light of the Current Financial Crisis

E-print/Working paper (2010)

L’action extérieure de l’Union européenne, Fondements, Moyens, Principes

Book published by LGDJ (2010)

The book studies the role of the European Union as an international global actor. The specific external competences of the Union interfere through the coherence requirement and the global approach of the ... [more ▼]

The book studies the role of the European Union as an international global actor. The specific external competences of the Union interfere through the coherence requirement and the global approach of the external objectives according to the Lisbon Treaty. The obligation of loyal cooperation reinforces the unity of the external action of the Union and its Member States, and the respect of international law favours its credibility. The first part of the book studies the external action of the Union from the perspective of the principle of conferral, while the second part emphasises the legal basis of the effectiveness of the external action allowing the Union to be considered as a credible and influent global actor. [less ▲]

Adaptive Sliding Mode Control Design for a Class of Nonlinear Systems with Unknown Dead Zone of Unknown Bounds

in Abstract book of 1st International Conference on Energy, Power, and Control (2010, December)

The control problem for a class of nonlinear systems that contain the coupling of unmeasured states and unknown parameters is addressed. The system actuation is assumed to suffer from unknown dead zone ... [more ▼]

The control problem for a class of nonlinear systems that contain the coupling of unmeasured states and unknown parameters is addressed. The system actuation is assumed to suffer from unknown dead zone nonlinearity. The parameters bounds of the unknown dead zone to be considered are unknown. Adaptive sliding mode controller, unmeasured states observer, and unknown parameters estimators are suggested such that global stability is achieved. Simulation for a single link mechanical system with unknown dead zone and friction torque is implemented for proving the efficacy of the suggested scheme. [less ▲]

Hoe (on)geletterden lezen: Receptie van het linguïstisch landschap op het Gambiaanse platteland

in Toegepaste Taalwetenschap in Artikelen (2010), 84(2), 19-28

This paper presents an explorative study on the reception of visual messages in the public space of village community in The Gambia. For this study, images of billboards and other signs along the main ... [more ▼]

This paper presents an explorative study on the reception of visual messages in the public space of village community in The Gambia. For this study, images of billboards and other signs along the main road were shown to twenty villages. They were asked what the images represented and how they knew this. It appeared that the interpretation of visual messages was based on more than the decoding of graphic symbols alone. Other semiotic signs play an important role as well. Twelve different types of interpretation were identified. It was concluded that a dichotomy of literate vs. illiterated does not capture the complexity of the distribution of reading skills in this society. [less ▲]

Compatibility of the SAFE FOODS Risk Analysis Framework with the legal and institutional settings of the EU and the WTO

in Food Control (2010), 21(12), 1638-1652

This paper analyses the compatibility of the SAFE FOODS recommendations with the food safety governance systems of the EU and the World Trade Organisation (WTO), in which standard setting procedures of ... [more ▼]

This paper analyses the compatibility of the SAFE FOODS recommendations with the food safety governance systems of the EU and the World Trade Organisation (WTO), in which standard setting procedures of the Codex Alimentarius Commission (CAC) are considered most relevant. The objective is to better understand the implications from (1) the addition of formalised framing and evaluation stages to the risk analysis process and (2) the expansion of the scope of the risk assessment to comprise the distribution of risks, benefits and costs of regulatory measures. The paper concludes that these recommendations of the SAFE FOODS project are compatible to EU law provided they are fine-tuned to legal provisions on specific roles for agencies, EU Member States and the European Commission services. All recommendations are deemed largely compatible with the rules for procedure of the CAC. [less ▲]

De l’intérêt de la théorie, de la théorie générale de l’Etat, de la théorie constitutionnelle. A propos d’un livre récent de Matthias Jestaedt

in Jus Politicum : Revue internationale de droit politique (2010), 5

La science du droit constitutionnel a-t-elle besoin d’une théorie générale de l’Etat ou/et d’une théorie constitutionnelle ? A l’heure où le savoir traditionnel de la théorie générale de l’Etat traverse ... [more ▼]

La science du droit constitutionnel a-t-elle besoin d’une théorie générale de l’Etat ou/et d’une théorie constitutionnelle ? A l’heure où le savoir traditionnel de la théorie générale de l’Etat traverse une crise existentielle, le présent article voudrait susciter et relancer un débat épistémologique qui, en France, à l’inverse de l’Allemagne, est trop souvent escamoté. A ce titre, il présente une recension détaillée et critique du livre publié récemment par Matthias Jestaedt, Die Verfassung hinter der Verfassung. Eine Standortbestimmung der Verfassungstheorie (La Constitution derrière la Constitution. Un positionnement de la théorie constitutionnelle), F. Schöningh, Paderborn, 2009, dans lequel l’auteur, s’inspirant à la fois du normativisme viennois et de la philosophie herméneutique, déploie une réflexion profonde sur l’objet, la méthode et la raison d’être de la théorie constitutionnelle. [less ▲]