Specific absorption rate reduction based on outage probability analysis for wireless capsule endoscope with spatial receive diversity

This study investigates the effect of spatial receive diversity on specific absorption rate (SAR) reduction based on outage probability analysis for wireless capsule endoscope (WCE). The communication performance of WCE depends much on the transmit power, which is strictly regulated in order to satisfy a safety guideline in terms of SAR, whereas WCE requires high communication performance due to its real-time data transmission. For the purpose of SAR reduction for a WCE scenario, the authors pay attention to the expectation that applying spatial diversity reception to WCE systems can not only improve the wireless communication performance but also reduce SAR. To begin with, based on finite-difference time-domain simulations with a numerical human body model, the outage probability is calculated under this implant propagation channel and the required transmit power is derived to secure a permissible outage probability. Then, the local peak SAR is calculated under the required transmit power when the WCE moves through the digestive organs. Finally, the simulation results demonstrate that applying spatial diversity reception can significantly reduce SAR for WCE.