Opportunistic Interference Alignment in MIMO Interference Channels

We present two interference alignment techniques such that an opportunistic point-to-point multiple input multiple output (MIMO) link can reuse, without generating any additional interference, the same frequency band of a similar pre-existing primary link. In this scenario, we exploit the fact that under power constraints, although each radio maximizes independently its rate by water-filling on their channel transfer matrix singular values, frequently, not all of them are used. Therefore, by aligning the interference of the opportunistic radio it is possible to transmit at a significant rate while insuring zero-interference on the pre-existing link. We propose a linear pre-coder for a perfect interference alignment and a power allocation scheme which maximizes the individual data rate of the secondary link. Our numerical results show that significant data rates are achieved even for a reduced number of antennas.Comment: To appear in proc. IEEE PIMRC 2008 - Workshop in Emerging Network Perspectives in Multiuser and Cooperative MIMO (NWMIMO). 5 pages and 4 figure

Performances asymptotiques de récepteurs sur le lien descendant de l'UMTS-FDD

- Dans ce papier, nous présentons un estimateur de l'influence des différentes sources d'interférences sur les performances d'un terminal mobile dans un réseau de type UMTS-FDD. A l'aide de cet estimateur, nous étudions l'impact de ces interférences dans un environnement réaliste. Enfin, nous montrons qu'il est possible d'améliorer les performances du mobile en utilisant plusieurs capteurs et en blanchissant spatialement le signal reçu

Estimation des paramètres de propagation d'un canal MIMO par l'algorithme ESPRIT-Unitaire multidimentionnel

- Dans ce travail, nous proposons une extension de l'algorithme ESPRIT-Unitaire au cas multidimensionnel (6D) afin d'estimer les différents paramètres du canal radio régi par un modèle de propagation en rayons. Cette méthode nous permet d'estimer pour un système MIMO (Multi-Input Multi-Output) tous les paramètres utiles des rayons, i.e. les angles d'émission et de réception (azimuth et élévation), les retards, les dopplers et les amplitudes complexes. On établit aussi la robustesse de cette méthode vis à vis d'une surestimation du nombre de trajets 'effectifs' du canal. Cette robustesse nous permet, en particulier, de nous affranchir de l'étape 'délicate' de l'estimation du nombre de trajets. Nous présentons quelques résultats de simulation permettant d'évaluer l'efficacité de cette nouvelle méthode et d'illustrer sa robustesse vis à vis de la méconnaissance du nombre de trajets

The Latest Mars Climate Database (MCD v5.1)

For many years, several teams around the world have developed GCMs (General Circulation Model or Global Climate Model) to simulate the environment on Mars. The GCM developed at the Laboratoire de Météorologie Dynamique in collaboration with several teams in Europe (LATMOS, France, University of Oxford, The Open University, the Instituto de Astrofisica de Andalucia), and with the support of ESA and CNES is currently used for many applications. Its outputs have also regularly been compiled to build a Mars Climate Database, a freely available tool useful for the scientific and engineering communities. The Mars Climate Database (MCD) has over the years been distributed to more than 150 teams around the world. Following the recent improvements in the GCM, a new series of reference simulations have been run and compiled into a new version (version5.1) of the Mars Climate Database, released in the first half of 2014. To summarize, MCD v5.1 provides: - Climatologies over a series of dust scenarios: standard year, cold (ie: low dust), warm (ie: dusty atmosphere) and dust storm, all topped by various cases of Extreme UV solar inputs (low, mean or maximum). These scenarios differ from those of previous versions of the MCD (version 4.x) as they have been derived from home-made, instrument-derived (TES, THEMIS, MCS, MERs), dust climatology of the last 8 Martian years. - Mean values and statistics of main meteorological variables (atmospheric temperature, density, pressure and winds), as well as surface pressure and temperature, CO2 ice cover, thermal and solar radiative fluxes, dust column opacity and mixing ratio, [H20] vapor and ice columns, concentrations of many species: [CO], [O2], [O], [N2], [H2], [O3], ... - A high resolution mode which combines high resolution (32 pixel/degree) MOLA topography records and Viking Lander 1 pressure records with raw lower resolution GCM results to yield, within the restriction of the procedure, high resolution values of atmospheric variables. - The possibility to reconstruct realistic conditions by combining the provided climatology with additional large scale and small scale perturbations schemes. At EGU, we will report on the latest improvements in the Mars Climate Database, with comparisons with available measurements from orbit (e.g.: TES, MCS) or landers (Viking, Phoenix, MSL)

Méthode hybride de suppression d'interférence basée sur l'estimation par paquet des codes inconnus appliquée au HSDPA multicode

Cet article traite la suppression des interférences causées par l'utilisation des multicodes du HSDPA et ceux des autres utilisateurs lorsque le canal est sélectif en fréquence. La taille fixe des codes d'étalement pour tout les utilisateurs HSDPA rend réalisable l'estimation des codes inconnus au récepteur. Un récepteur hydbride SIC/PIC utilisant deux étapes différentes d'annulation souple d'interférence est proposé

Détection et démodulation de stations de base dans le réseau UMTS

PARIS-EST Marne-la-Vallee-BU (774682101) / SudocSudocFranceF

Game Theory for Dynamic Spectrum Access

Print ISBN: 978-1-4200-7775-9In this chapter, the competitive interaction of radio devices dynamically accessing the spectrum is studied using tools from game theory. Depending on the scenario under consid- eration, the dynamic spectrum access (DSA) is modeled by different types of games following both a non-cooperative and a cooperative approach. In the first case, each radio device aims to selfishly maximize an individual performance metric (e.g., individual data rate), while in the second case such maximization concerns global network parameters (e.g., network sum-rate). In each case, we analyze network equilibria, which allow network designers, oper- ators, or manufactures to predict the behavior and performance of cognitive networks and/or terminals