Wearable Human Body Communication Channel Measurements in the Body Resonance Regime

Over the last couple of decades, Human Body Communication (HBC) has emerged as a promising alternative to wireless communication for energy-efficient data transfer using miniaturized wearable devices, and its channel characterization in the Electro-Quasistatics (EQS) regime has been widely explored. Moreover, three regions in the HBC channel characteristic, namely EQS, Body Resonance (BR), and Device Resonance (DR), over a broad frequency range from 100 kHz to 1 GHz, have been conceptualized. The BR region, with high channel gain (CG) and bandwidth, can potentially inspire the design of more power-efficient HBC systems than the state-of-the-art. In this paper, the channel measurements focusing on the body resonance regime (30 MHz to 250 MHz measurement frequency range) and variability caused by the receiver (Rx) position change are studied through measurements with wearable devices. Results illustrate that the human body improves the CG by ~v45 dB compared with transmission through the air. The placement of the receiver near the shoulder causes severe attenuations in CG, and higher frequencies cause larger CG undulation. Moreover, with T-posture, the body resonance peak appears between 100 and 150 MHz, which helps to select an optimum frequency for the HBC system design, supporting high data rates and power efficiencies.