Hybrid propagation channel modelling for city area land mobile satellite communications

13 pagesInternational audienceIn this study, a hybrid model is proposed to simulate the realistic channel behavior for urban city land mobile satellite (LMS) communications. It associates the advantages of existing models in that different receiving states are predicted using a deterministic approach, whereas the channel behavior is simulated using adapted statistical laws. Using a geosynchronous satellite transmitter working at 1.5 GHz and a land mobile receiver, the hybrid model is validated for LMS channel. It leads to a high-performance simulation, combining accuracy (global simulation error less than 1 dBW) and small computation time (gain of about 10,000 times compared to a full deterministic reference model)

Une optimisation en temps de calcul pour la prédiction de zones de couverture radioélectriques

International audienceThis article presents a method which optimises the computation time for the prediction of a radio coverage, whatever the propagation model used. The principle consists in reducing the number of ap- plication points of the propagation model in relation to a classical technique. The proposed method is based on a multi resolution analysis of measured signals carried out around 2 GHz, and on an electroma- gnetic analysis of the propagation environment. The performances of the method are evaluated in term of reduction in computation time and of accuracy, in comparaison with the classical technique

Efficient 2D ray-tracing method for narrow and wide-band channel characterization in micro-cellular configurations

International audienceChannel characterization is an essential step to the development of outdoor or indoor wireless networks. Indeed, for multimedia applications, new radio mobile systems must accurately take into account channel behavior. In this paper, we propose an efficient 2D ray-tracing method to characterize the narrow and wide-band radio channels for a very large number of receivers in micro-cellular configurations. It is based on a quick pre-calculation of an exact 2D visibility graph. The proposed method follows an ITU recommendation, which advocates, for wide-band characterization, only considering the paths included in a 18 dB dynamic range of power impulse response. Contrary to the classical approach, which consists in thresholding the complete impulse response in a post-treatment, our method only computes the significant paths. The interest of the proposed method resides in its significant computation time reduction factor, in comparison with the classical approach and this without any significant loss in accuracy. Received power and wide-band parameter maps are computed for about 40,000 receivers, in a dense urban environment, and are provided with an approximate reduction factor of 4 and 80% of null estimation error in comparison to a classical approach

Simulation of radio wave propagation in arched cross section tunnels

5 pagesInternational audienceSince several years, wireless communication systems are developed for train to infrastructure communication needs related to railway or mass transit applications. The systems should be able to operate in specific environments like tunnels. In this context, specific radio planning tools have to be developed to optimise system deployment. Realistic tunnels geometries are generally of rectangular cross-section or arched shape. Furthermore, they are mostly curved. In order to calculate electromagnetic wave propagation in such tunnels, specific models have to be developed. Several works dealt with retransmission of GSM or UMTS [1], [2]. Few theoretical or experimental works focused on 2.4 GHz or 5.8 GHz bands. In this paper, we will propose an approach to model radio wave propagation in these frequency bands in arched shape cross-section straight tunnels using tessellation in multi-facets. The model will be based on a Ray-Tracing tool using images method. Work reported in this paper will also show the propagation loss variations according to the shape of tunnels. A parametric study on the size of facets to model the cross-section will be realized. Finally, the influence of some parameters like the dimensions of tunnels and the frequency of signals will be examined

Modélisation et simulation efficaces du canal de propagation optique sans fil en environnement réel.

National audienceCe papier présente nos travaux concernant la simulation du canal optique sans fil. Cel le-ci repose sur l'utilisation d'un lancé de rayons 3D associé à des méthodes de Monte-Carlo visant à résoudre efficacement, en environnement réel, l'équation d'il lumination globale modélisant la propagation de la lumière

Asymptotic models and curved surfaces : application to railway transportation

5 pagesInternational audienceSeveral wireless communication systems are developed for communication needs between train and ground or between trains in the railway or mass transit domains. In order to deploy these systems in specific environments, such as tunnels, straight or curved, rectangular or arch-shaped section, specific propagation models have to be developed. In this paper, we propose a method to model the radiowave propagation in straight arch-shaped tunnels by using asymptotic methods, such as ray tracing and ray launching, combined with the tessellation of the arched section. A method of interpolation of the facets normals is implemented in order to minimize the error made when using the tessellation. These results are compared to those found in the literature in order to validate our approach

Modélisation hybride du canal radio dans un contexte industriel

National audienceCe papier présente un modèle hybride de canal pour les communications en milieu industriel s'inspirant d'une méthode à tracé de rayon et du modèle de Winner II. L'originalité de ce modèle repose sur son caractère hybride consistant, en prétraitement, à partitionner l'environnement en zones de visibilité ou de non visibilité "faible" et "forte" sur des critères déterministes liés à la propagation des ondes. Un modèle statistique reprenant le concept de cluster est ensuite joué au sein de chacune des ces zones reproduisant ainsi fidèlement l'évolution des paramètres caractéristiques des clusters identifiés

An acceleration technique for the radioelectric coverage prediction in small and microcell configurations

The purpose of this work is to optimise the necessary computation time for the coverage zone prediction. Several approaches exist to reduce the calculation time; they consist in simplifying the complexity of the used propagation model. Here, our method is different but complementary of the previous approaches. Indeed, it is independent of the propagation model and tries to reduce the number of application points of the considered model for the coverage prediction. Thus, the performances of our optimised method in term of accuracy and computation time is presented in this articl

Comparaison du modèle géométrique "WINNER II" à un modèle déterministe basé rayon : Application aux contextes industriels

National audienceCe papier présente une comparaison des résultats de modélisation du canal radio en milieu industriel indoor, issu du modèle statistique WINNER d'une part, et d'un modèle déterministe tridimensionnel basé rayons allié à des méthodes asymptotiques enfréquence d'autre part. Cette comparaison est réalisée à partir des paramètres larges bandes que sont le retard moyen et la dispersion des retards calculés sur un grand nombre de réponses impulsionnelles issues des deux modèles. Les premiers résultats montrent que le comportement est similaire d'un modèle à l'autre et que WINNER est plus pessimiste

Utilisation des techniques MIMO pour des transmissions robustes et haut-débit en tunnels.

National audienceCe papier illustre le gain de performance potentiel apporté par l'utilisation des techniques MIMO dans le cadre des communications radio en tunnel ferroviaire. Différents schémas de transmission sont testés et évalués dans le cas de canaux faiblement puis fortement corrélés