SAR evaluation based on required BER performance for 400 MHz implant BANs

Implant body area networks (BANs) have so far drawn considerable attention in biomedical applications. Although implant BANs require high throughput performance of wireless communication due to real-time data transmission, the transmit power is strictly regulated in order to satisfy a safety guideline in terms of specific absorption rate (SAR). In this paper, we evaluate the local peak SAR based on required bit error rate (BER) performance for implant BANs at 400 MHz medical implant communication service (MICS) band. To begin with, we first perform finite-difference time-domain (FDTD) simulations for implant BAN propagation with a numerical human body model, and derive the propagation characteristic of implant BAN signals. Then, we calculate the BER performance under this implant propagation channel and derive the required transmit power to secure a permissible BER. Finally, we calculate the local peak SAR under the required transmit power when the implant transmitter moves along the digestive organs. Based on such an approach, we attempt to determine a threshold transmit power which could be used to ensure the induced SAR not exceeding the safety guideline.