2 research outputs found
Développement d'une méthodologie pour l'évaluation de l'exposition réelle des personnes aux champs électromagnétiques
The work presented in the thesis is directed towards addressing the requirement for determining the radio frequency (RF) exposure due to mobile phones under typical usage/ real-life scenarios and also to develop a method to predict and compare mobile phones for their real-life RF exposure. The mobile phones are characterized for their specific absorption rate (SAR) and for transmit and receive performance given by the over-the-air (OTA) characterization. Using the SAR and the total radiated power (TRP) characterization, an exposure index referred to as the SAROTA index was previously proposed to predict the real-life exposure due to mobile phones which would also serve as a metric to compare individual phones. In order to experimentally determine the real-life RF exposure, various software modified phones (SMP) are utilized for the study. These phones contain an embedded software capable of recording the network parameters. The study is undertaken in the following order: (a) Characterization of the available tools and resources for performing targeted measurements/experiments, (b) identifying the important radio resource parameters and metrics to perform the targeted measurements, (c) investigation of the actual implementation of the power control mechanism in a live network for various received signal level and received quality environments, (d) investigating the correlation of the over-the-air performance of the mobile phones and the extent of actual power control realization, (e) comparing the actual exposure and the real-life exposure as predicted by the SAROTA index. Based on the logistical and technical challenges encountered, the experiments were restricted to indoor environments to enable repeatability. During the first phase of the study, the stability of the indoor environment was evaluated. During the second phase, the influence of hand phantom on the SAR and TRP of the mobile phones and the capability of the SAROTA index to predict the exposure was investigated. Further developing on the insights from the hand phantom experiments, in the third phase, a set of identical software modified phones were externally modified to alter the TRP performance and the methodology to determine the real-life exposure and also verify the capability of the SAROTA index to predict the exposure levels was investigated. The experiments demonstrate that the SAROTA index is capable of predicting the real-life exposure and comparing the mobile phones.Le travail prĂ©sentĂ© dans cette thĂšse a pour objectif lâĂ©tude des conditions nĂ©cessaires pour Ă©valuer l'exposition radio frĂ©quence (RF) due aux tĂ©lĂ©phones mobiles dans un scenario dâutilisation rĂ©elle et le dĂ©veloppement dâune mĂ©thodologie permettant de prĂ©dire et de comparer les tĂ©lĂ©phones mobiles en fonction de leurs expositions RF rĂ©elles. Les tĂ©lĂ©phones mobiles sont caractĂ©risĂ©s par leur dĂ©bit d'absorption spĂ©cifique (DAS) et leur performance en Ă©mission et en rĂ©ception (over-the-air, OTA). En utilisant le DAS et la puissance totale rayonnĂ©e (PTR), un indice d'exposition appelĂ©e l'indice SAROTA a Ă©tĂ© proposĂ© prĂ©cĂ©demment afin de prĂ©voir l'exposition rĂ©elle des tĂ©lĂ©phones mobiles. Lâindice SAROTA sert ainsi de mĂ©trique permettant de comparer les tĂ©lĂ©phones mobiles. Afin de dĂ©terminer expĂ©rimentalement lâexposition rĂ©elle aux RF, plusieurs tĂ©lĂ©phones avec des modifications logicielles permettant dâenregistrer les paramĂštres du rĂ©seau, sont utilisĂ©s pour lâĂ©tude qui est menĂ©e comme suit : (a) caractĂ©risation des outils et des ressources disponibles pour effectuer des mesures ciblĂ©es, (b) identification des ressources radio et des paramĂštres importants pour effectuer ces mesures, (c) Ă©tude de la mise en Ćuvre effective du mĂ©canisme de contrĂŽle de puissance observĂ© dans un rĂ©seau mobile rĂ©el pour diffĂ©rents niveaux et de qualitĂ©s du signal reçus, (d) Ă©tude de la corrĂ©lation entre la performance OTA des tĂ©lĂ©phones mobiles et lâĂ©tendue effective du contrĂŽle de puissance appliquĂ©e par le rĂ©seau, (e) comparaison entre la valeur rĂ©elle de lâexposition et la valeur prĂ©dite en utilisant lâindice SAROTA. Comme les dĂ©fis logistiques et techniques sont plus difficiles Ă surmonter pour les mesures dans un environnement multi-trajets extĂ©rieur, les expĂ©riences ont Ă©tĂ© limitĂ©es Ă des environnements intĂ©rieurs pour assurer une meilleure rĂ©pĂ©tabilitĂ© des mesures. Lors dâune premiĂšre phase de lâĂ©tude, la stabilitĂ© de lâenvironnement intĂ©rieur a Ă©tĂ© Ă©valuĂ©e. Lors dâune deuxiĂšme phase, lâinfluence de la main sur le DAS et la PTR des tĂ©lĂ©phones mobiles ainsi que sur lâĂ©valuation de lâexposition rĂ©elle prĂ©dite par lâindice SAROTA a Ă©tĂ© Ă©tudiĂ©e. Lors dâune troisiĂšme phase, un ensemble de tĂ©lĂ©phones mobiles identiques ont Ă©tĂ© modifiĂ©s et des mesures effectuĂ©es pour vĂ©rifier que lâindice SAROTA permet bien de prĂ©dire lâexposition rĂ©elle des personnes