Ourouk Jawad

A HUMAN BODY MODEL EXPOSED TO A CLUSTER OF WAVES: A STATISTICAL STUDY OF SAR

The impact of wireless channel modeling on exposure to electromagnetic radiation is studied. Two methods are developed in order to assess the statistical properties of whole body Speciflc Absorption Rate for exposure estimation in indoor environment. The body model is exposed to a bundle of waves, named cluster, following the wireless channel modeling approach. The flrst method is analytical and based on the Uncorrelated Scattering Assumption of the incident waves. The second method is a classical stochastic method. The point is to identify the parameters of Wireless Channel which led to signiflcant SARs variation.

Study of Human Exposure Using Kriging Method

This paper develops the kriging method to calculate the whole body Specific Absorption Rate (SAR) for any angle of incidence of a plane wave on any body model using a minimum number of Finite Difference Time Domain (FDTD) simulations. Practical application of this method is to study peoples exposure. Thanks to kriging method, it will enable to answer to the challenge of studying the exposure in a realistic environment. This approach develops a new tool in order to improve the field of stochastic dosimetry. The kriging method is applied to a girl body model in order to determine the variogram model, then this model is validated on a boy body model. Thanks to only 40 numerical SAR values, kriging method enables to estimate any SAR value with a mean relative error under 3%.

Estimation of specific absorption rate with kriging method

Summary form only given. The development of wireless technologies sets off new issues regarding exposure of the people to electromagnetic radiation. The non-ionizing dosimetry is focused on the calculation of the dose that can be absorbed by users of a wireless technology. The integration of the variability in the dosimetry is a major issue, especially the one led by the environment. Electromagnetic environment are described by wireless channel model. The model indicates that the exposure of people is random; the channel parameters follow known probability distributions. This model shows that the electromagnetic waves do not arrive separately but in cluster form. The angles of incidence and amplitudes of the electromagnetic waves follow specific probability distribution. In the framework of the study of peoples exposure to complex environment, it is necessary to expose an anatomical body model to all possible angle of incidence. The computation time in dosimetry is especially long so it is essential to pitch for an efficient estimation method in order to obtain the SAR values for all possible angle of incidence. In this study, we look into estimation of SAR in function of azimuthal angle of arrival of the electromagnetic wave. Kriging method which proves its efficiency in many domains will be used to respond to this problem. The kriging method is a stochastic spatial interpolation method which estimates a value of a phenomenon at locations where no calculation or measure has been done and also estimation variance (called kriging variance). In the full paper an estimation method of whole body SAR based on kriging approach will be presented in order to decrease the number of FDTD calculation. In the full detailed results will be presented, showing the impact of the number of SAR values taken in kriging estimation.

Sensitivity of Whole-Body Dosimetry to Channel Model Parameters

Impact of channel model parameters on the whole-body specific absorption rate (SAR) is studied. Closed-form expressions are derived for the mean value and the standard deviation of the SAR, taking into account the random nature of the channel parameters. Total sensitivity indices of the SAR with respect to the channel parameters are derived. They are estimated using a Monte-Carlo approach. Noninfluential channel parameters are identified. They are then suppressed from channel models for dosimetry purpose.

Sensitivity analysis of the specular and diffuse parts of clusters multipath on the exposure of a child body model

This paper studies the sensitivity of whole body Specific Absorption Rate (SAR) to indoor propagation channel parameters. Channel parameters are presented. SAR expectation over complex amplitude is analytically expressed. Then, total sensitivity index to channel parameters are estimated by a Monte Carlo approach and most influential parameters are extracted from this study.