Channel Variability of Body-Resonance Human Body Communication

Human body communication (HBC), as an energy-efficient alternative to radio-frequency (RF) communications, was extensively explored in terms of its channel variability in the electro quasi-static (EQS) band. The body resonance (BR) region, offering larger channel gain and bandwidth, potentially enables higher-speed data transfer, further improving HBC channel capability and energy efficiency. However, BR HBC channel variability still needs considerable exploration. This paper comprehensively analyzes BR HBC channel variability across different device positions, postures, and device sizes, including ground sizes and separations between signal and ground electrodes, through simulation and measurement with miniaturized wearable devices at 30 MHz∼300 MHz. Results show larger ground sizes and electrode separations increase the channel gain by up to 20.5 dB. The channel gain is reduced when devices are close to the torso, but it improves when they are positioned on the same arm or in direct line-of-sight. These findings demonstrate that factors affecting the EQS HBC channel also apply to BR HBC, facilitating further understanding of BR HBC channel characteristics.