An ultra wideband communication channel model for the human abdominal region

Long-term implantable devices communicating with receivers in the outer human body through a wireless interface are one of the most prominent applications of micro/nano-technology in medicine. Ultra wideband (UWB) interfaces have great potential for the communication links of these telemedicine applications due to their inherent low power consumption, high transmission rates, and simple electronics. Novel implant medical sensors and actuators operate in the abdomen at different depths, which makes an "abdominal" channel model essential for the proper design of the UWB communication interfaces of said devices. This paper presents a statistical model for the propagation of a UWB pulse through the abdominal region in the 1-6 GHz frequency band. For the development of this statistical model, numerical electromagnetic (EM) simulations were conducted using a digital anatomical model that includes the dielectric properties of human tissues; using this EM simulator, the channel responses of many in-body probes were computed. Based on the statistical analysis of the obtained data, we provide the mathematical expressions to calculate the path loss and shadowing at depths between 10-150 mm inside the abdomen. In addition, the channel impulse response (CIR) can be reproduced using a set of statistical formulas also provided. Our proposed model approximates very well the abdominal in-body channel properties, thereby eliminating the need for time-consuming and complex numerical simulations.