Time domain measurements for UWB on-body radio propagation

Wireless body area network (BAN) has being a subject of growing interest in recent years. It allows the monitoring of health information with the help of sensors utilizing low power technology such as ultra-wideband (UWB) systems. Scanning the existing literature reveals that most experimental studies on BAN channel have been conducted with human object in a standing position. Alomainy et al. have performed a measurement campaign to investigate UWB on-body radio channels with some sitting body scenarios. Nevertheless, very few antenna positions have been considered for each sitting scenario. In this work, we demonstrate experimental investigations of UWB on-body propagation when the human object is in the sitting position, as the sitting posture may be the most common behavior for people living a sedentary lifestyle. A large number of data points are collected to facilitate a comprehensive characterization of the BAN channel. Vector network analyzer has been typically used in the previous measurements to obtain the S21 parameter for analysis. In the current work, time domain apparatus are employed. An UWB pulse generator is used to send an extremely short pulse around the body and the signal is picked up by a time-domain digital communications analyzer (sampling oscilloscope). From the received data, simple signal processing algorithms are used to extract the relevant channel parameters including the path loss and the signal power variation. Such information could provide useful insight into designing efficient body-centric radio systems.