Analysis of the influence of the power control and discontinuous transmission on RF exposure with GSM mobile phones

Biological studies and, in particular, epidemiological ones require the estimation of the RF exposure induced by a mobile phone. Due to the different techniques used by global system mobile (GSM) and digital communication system (DCS) such as power control and discontinuous transmission, the power emitted by a handset is largely variable. As these parameters depend on the environment and the network strategy, individual exposure level is difficult to evaluate a priori. An analysis of the relative influence of the main parameters is performed and a method of statistical analysis based on measurement is proposed to estimate and characterize the exposure level in an operating network. Using a test mobile system, the data stream between the mobile and the base station, and, in particular the power control level, has been recorded along routes in Paris and its vicinity. Statistical parameters such as mean value, standard deviation, level crossing rate, and average duration fading have been extracted from these data. These parameters, which characterize the RF exposure induced by a GSM handset in an operating network, have been applied to a generic handset to evaluate the characteristics of the power absorbed by specific biological tissues using the finite-difference time-domain (FDTD) method.