Multiuser detection in a dynamic environment Part I: User identification and data detection

In random-access communication systems, the number of active users varies with time, and has considerable bearing on receiver's performance. Thus, techniques aimed at identifying not only the information transmitted, but also that number, play a central role in those systems. An example of application of these techniques can be found in multiuser detection (MUD). In typical MUD analyses, receivers are based on the assumption that the number of active users is constant and known at the receiver, and coincides with the maximum number of users entitled to access the system. This assumption is often overly pessimistic, since many users might be inactive at any given time, and detection under the assumption of a number of users larger than the real one may impair performance. The main goal of this paper is to introduce a general approach to the problem of identifying active users and estimating their parameters and data in a random-access system where users are continuously entering and leaving the system. The tool whose use we advocate is Random-Set Theory: applying this, we derive optimum receivers in an environment where the set of transmitters comprises an unknown number of elements. In addition, we can derive Bayesian-filter equations which describe the evolution with time of the a posteriori probability density of the unknown user parameters, and use this density to derive optimum detectors. In this paper we restrict ourselves to interferer identification and data detection, while in a companion paper we shall examine the more complex problem of estimating users' parameters.Comment: To be published on IEEE Transactions on Information Theor

Emancipaciones. Acerca de la aprobación de la ley del matrimonio igualitario y la ley de identidad de género en la Argentina

La pregunta fundamental de partida es: ¿cómo es que en la Argentina llegamos a la aprobación de estas dos leyes? Y esta pregunta necesariamente me remite a dos cuestiones: al contexto discursivo general de la aprobación de las normas –y esto me va a remitir directamente a la política y la articulación política populista que gobierna en la Argentina desde 2003- y a los debates y el impacto de las leyes en la comunidad LGBT.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Acerca del psicoanálisis y la política. Una introducción al pensamiento de Ernesto Laclau

Seminario dirigido a profesores, investigadores y estudiantes de másterEl objetivo del seminario es presentar la relación entre el psicoanálisis y la teoría política contemporánea a partir de la propuesta del análisis del discurso elaborada por Ernesto Laclau y Chantal Mouffe, que ha inaugurado la corriente de pensamiento posmarxista. En ese sentido, se presentarán los argumentos básicos de la deconstrucción del marxismo realizada por estos dos autores y los elementos clave que toman del psicoanálisis para desarrollar su propio corpus teórico. 1) La deconstrucción del marxismo. Gramsci y Althusser. a) El uso laclausiano de la interpretación de los sueños de Freud. El concepto de sobredeterminación. b) El uso laclausiano de Introducción del narcisismo de Freud. El individuo es imposible, la sociedad también. c) Hegemonía y antagonismo.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Large-System Analysis of Multiuser Detection with an Unknown Number of Users: A High-SNR Approach

We analyze multiuser detection under the assumption that the number of users accessing the channel is unknown by the receiver. In this environment, users' activity must be estimated along with any other parameters such as data, power, and location. Our main goal is to determine the performance loss caused by the need for estimating the identities of active users, which are not known a priori. To prevent a loss of optimality, we assume that identities and data are estimated jointly, rather than in two separate steps. We examine the performance of multiuser detectors when the number of potential users is large. Statistical-physics methodologies are used to determine the macroscopic performance of the detector in terms of its multiuser efficiency. Special attention is paid to the fixed-point equation whose solution yields the multiuser efficiency of the optimal (maximum a posteriori) detector in the large signal-to-noise ratio regime. Our analysis yields closed-form approximate bounds to the minimum mean-squared error in this regime. These illustrate the set of solutions of the fixed-point equation, and their relationship with the maximum system load. Next, we study the maximum load that the detector can support for a given quality of service (specified by error probability).Comment: to appear in IEEE Transactions on Information Theor

On Medieval Ethnography : Marco Polo and Mandevilla’s Orient

Este artículo estudia la visión del Oriente en las traducciones al aragonés de los libros de Marco Polo y John Mandeville. En particular, se analizan el Oriente y sus muchedumbres, las “nuevas maravillas" de Marco Polo y las maravillas etnográficas de Juan de Mandevilla.This article analyzes the image of the Orient in the aragonese translations of the books by Marco Polo and John Mandeville. In particular, it focuses on the multitudes, the “new marvels" by Marco Polo and the ethnographic marvels by Mandeville.Fil: Biglieri, Aníbal A.. University of Kentuck

Low-Density Parity-Check Codes for Nonergodic Block-Fading Channels

We solve the problem of designing powerful low-density parity-check (LDPC) codes with iterative decoding for the block-fading channel. We first study the case of maximum-likelihood decoding, and show that the design criterion is rather straightforward. Unfortunately, optimal constructions for maximum-likelihood decoding do not perform well under iterative decoding. To overcome this limitation, we then introduce a new family of full-diversity LDPC codes that exhibit near-outage-limit performance under iterative decoding for all block-lengths. This family competes with multiplexed parallel turbo codes suitable for nonergodic channels and recently reported in the literature.Comment: Submitted to the IEEE Transactions on Information Theor

Populism, right-wing and left-wing position?

El artículo parte de la discusión actual sobre si la proliferación de los así denominados populismos de derecha invalida o no la tesis de Laclau de que el populismo es un tipo de articulación que puede dar un sentido emancipatorio a la iniciativa política. Dicho debate que se ha presentado fundamentalmente bajo la oposición binaria populismos de derechas frente a populismos de izquierda tiene a dos voces contrapuestas, las de Fassin y Mouffe, que el texto se propone revisar, desde una perspectiva laclausiana, a partir de dos preguntas que se desprenden de las posiciones políticas de los autores: ¿es posible, como desearía Fassin, eludir o eliminar el populismo? ¿Es posible distinguir entre un populismo de derechas y uno de izquierdas, como propone Mouffe?The article takes as a point of departure the current discussion about the proliferation of the so called right-wing populisms that put into question Laclau’s thesis that populism is a sort of articulation that may bring about emancipatory directions to politics. This debate, that has recently taken the format of an opposition between right-wing populism vs. leftwing populisms, has two main competing voices —Fassin and Mouffe— that the text reviews from a Laclausian perspective. The two questions addressed, that rise from the political position of each author, are the following: is it possible to eliminate populism as Fassin would prefer? Is it possible to establish a differentiation between right-wing and left-wing populism as Mouffe affirms?The article takes as a point of departure the current discussion about the proliferation of the so called right-wing populisms that put into question Laclau’s thesis that populism is a sort of articulation that may bring about emancipatory directions to politics. This debate, that has recently taken the format of an opposition between right-wing populism vs. leftwing populisms, has two main competing voices —Fassin and Mouffe— that the text reviews from a Laclausian perspective. The two questions addressed, that rise from the political position of each author, are the following: is it possible to eliminate populism as Fassin would prefer? Is it possible to establish a differentiation between right-wing and left-wing populism as Mouffe affirms

Hating the people! An anti-populist passion: The case of the Argentinean political alliance ''Let’s Change''

The aim of this article is to contribute to the understanding of anti-populist formationsthrough exploring the way in which they are structured. The hypothesis that guides this inquiry is that hatred is the affect that structures anti-populism. First, anti-populism is defined by contrasting it to a minimum basic definition of populism. Second, studying ? as a case study ? the latest and current antipopulist formations in Argentina (the political alliance called Cambiemos ? Let?s Change). In this regard, following the ?evidential paradigm? of Carlo Ginzburg some speech pieces of supporters, leaders and mass-media journalist linked to ?Let?s Change? are picked up. Third, drawing upon Freudian and Lacanian psychoanalytical tools within the general theoretical framework provided by Ernesto Laclau these pieces are analysed to determine how hatred is the affect which structures anti-populism. Finally, conclusions related to the political effects of anti-populism on the political and the democratic practices are delineated.Fil: Biglieri, Paula Andrea. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Instituto Interdisciplinario de Estudios e Investigación de América Latina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

The Names of the Real in Laclau’s Theory: Antagonism, Dislocation, and Heterogeneity

This article presents an overview of Ernesto Laclau’s theory of hegemony from his first work as co-author with Chantal Mouffe of Hegemony and Socialist Strategy: Towards a Radical Democratic Politics (1985) to his last work On Populist Reason (2005). To that end, this corpus is analyzed with theoretical tools from Lacanian psychoanalysis in order to locate the implicit postulates in Laclau’s work and to organize his work into three main stages. We propose an interpretation of such theory from a psychoanalytic perspective through three key concepts: antagonism, dislocation, and heterogeneity