No abstract

No abstract

No abstract

Introduction Français. J'ai dressé une liste de mes publications pour essayer de m'y retrouver. Elle peut avoir aussi une certaine utilité pour d'autres. Cette liste estàestà peu prèscompì ete, sauf pour les publications les plus anciennes. Je n'y ai pas inclus des rapports internes que j'ai rédigésrédigésà la Thomson (en-tre 1966 et 1973) sur desprobì emes plus divers que ceux de la liste, mais seulement mentionné les titres de quelques brevets de cette période. La langue employée dans le titre est toujours celle de l'article. Des sommaires de certaines publications (estimées les plus importantes, surtout parmi les plus récentes) précèdent la liste proprement dite. Pour la plupart des articlesécritsarticlesécrits en français, le résumé en anglais publié avec l'article ('abstract' ou 'summary') est joint au sommaire français ; si la langue de la publication est l'anglais, il n'y a le plus souvent qu'un sommaire anglais. J'ai aussi mentionné quelques travaux non terminés qui ont bien peu de chance de l'ˆ etre un jour, ainsi que des projets dont l'avenir est incertain. English. I compiled a list of publications in order to find my own way in my previous work. It may also have some usefulness for other people. This list is almost complete, except for the oldest publications. I did not include in it reports I wrote when working at Thomson (between 1966 and 1973) concerning more diverse problems than those of the list, but I mentioned the titles of some patents of this time. The language of the title is always that of the paper. Summaries or abstracts of certain publications (those deemed the most important, especially among the most recent ones) precede the list itself. For most of the papers written in French, the abstract or summary in English is appended to the French summary as it was when the paper was published ; if the publication language is English, only an English summary is generally provided. I also mentioned few unfinished works which have little chance to be once completed, as well as projects of uncertain future. Sur l'emploi des signauxàsignauxà bande limitée dans la théorie des communications Sommaire de [7] On rappelle d'abord les difficultés et les paradoxes rencontrés dans l'utilisation des signauxà signauxà bande limitée en théorie des communications. L'examen critique du concept de spectre suggère de les interpréter en tenant compte du retard, en principe infini, impliqué dans leur définition même. L'hypothèse d'un retard infini paraˆıtparaˆıt suffire en ef-fetàfetà les résoudre. On montre ensuite qu'on préfère systématiquement, dans la technique des communications , la limitation du spectrè a la limitation (antagoniste) du retard, au profit de la qualité de transmission (notamment dans les systèmes multi-plex). Les signaux réels pouvant alorsêtrealorsêtre considérés comme des approximationsàapproximationsà retard fini des sig-nauxànauxà bande limitée, les seconds définissent une représentation pour les premiers, approchée asymp-totiquement quand le retard accepté pour les sig-naux réels tend v...

We propose a new framework to study the performance of cellular networks using a fluid model and we derive from this model analytical formulas for interference, outage probability, and spatial outage probability. The key idea of the fluid model is to consider the discrete base station (BS) entities as a continuum of transmitters that are spatially distributed in the network. This model allows us to obtain simple analytical expressions to reveal main characteristics of the network. In this paper, we focus on the downlink other-cell interference factor (OCIF), which is defined for a given user as the ratio of its outer cell received power to its inner cell received power. A closed-form formula of the OCIF is provided in this paper. From this formula, we are able to obtain the global outage probability as well as the spatial outage probability, which depends on the location of a mobile station (MS) initiating a new call. Our analytical results are compared to Monte Carlo simulations performed in a traditional hexagonal network. Furthermore, we demonstrate an application of the outage probability related to cell breathing and densification of cellular networks.

No abstract

International audience

In this paper, we address the problem of optimally placing relay nodes in a cellular network with the aim of maximizing cell capacity. In order to accurately model interference, we use a dynamic framework, in which users arrive at random time instants and locations, download a file and leave the system. A fixed point equation is solved to account for the interactions between stations. We also propose an extension of a fluid model to relay based cellular networks. This allows us to obtain quick approximations of the Signal to Interference plus Noise Ratio (SINR) that are very close to 3GPP LTE-A guideline results in terms of SINR distribution.We then use these formulas to develop a dedicated Simulated Annealing (SA) algorithm, which adapts dynamically the temperature to energy variations and uses a combination of coarse and fine grids to accelerate the search for an optimized solution. Simulations results are provided for both in-band and out-of-band relays. They show how relays should be placed in a cell in order to increase the capacity in case of uniform and non-uniform traffic. The crucial impact of the backhaul link is analyzed for in-band relays. Insights are given on the influence of shadowing.

Extensive research in recent years has shown the benefits of cognitive radio technologies to improve the flexibility and efficiency of spectrum utilization. This new communication paradigm, however, requires a well-designed spectrum allocation mechanism. In this paper, we propose an auction framework for cognitive radio networks to allow unlicensed secondary users (SUs) to share the available spectrum of licensed primary users (PUs) fairly and efficiently, subject to the interference temperature constraint at each PU. To study the competition among SUs, we formulate a non-cooperative multiple-PU multiple-SU auction game and study the structure of the resulting equilibrium by solving a non-continuous two-dimensional optimization problem. A distributed algorithm is developped in which each SU updates its strategy based on local information to converge to the equilibrium. We then extend the proposed auction framework to the more challenging scenario with free spectrum bands. We develop an algorithm based on the no-regret learning to reach a correlated equilibrium of the auction game. The proposed algorithm, which can be implemented distributedly based on local observation, is especially suited in decentralized adaptive learning environments as cognitive radio networks. Finally, through numerical experiments, we demonstrate the effectiveness of the proposed auction framework in achieving high efficiency and fairness in spectrum allocation.