Evaluation of the real life exposure due to GSM mobile phones

The radio frequency (RF) exposure due to mobile phones is currently characterized by measuring the specific absorption rate (SAR) under laboratory conditions with the mobile phone operating at the maximum power level. Under typical operating conditions, the network operators optimize the transmit level of a mobile phone by implementing a power control mechanism based on the channel characteristics such that the mobile phone does not always transmit at the maximum power level. This implies that the real life exposure experienced by the user for a given mobile phone use configuration will depend on the power transmitted by the mobile phone averaged over the duration of the call. In this study we propose a method to evaluate the real life exposure for a mobile phone in a given indoor environment. This is achieved by characterizing the received signal level (RXLEV) and quality (RXQUAL) of the traffic channel (TCH) for which the actual power control mechanism is implemented by the network operator and also taking into account the SAR and over the air (OTA) performance of the mobile phone. The measurements are performed by placing actual calls on hardware and/or software modified mobile phones that are capable of recording various radio resource parameters.