Measurement and Analysis of Electric Signal Transmission Using Human Body as Medium for WBAN Applications

Human body communications (HBCs) realize wireless body area networks (WBANs) using the human body as a transmission channel without wired or wireless connections. While presenting various approaches for measurement and analysis of the human body channel, previous studies require additional interpretations of their results to obtain practical design parameters for a desired communication system. This paper addresses the provision of specific design guidelines based on the proposed channel measurement for capacitive coupling HBC employing digital transmission, adopted in the IEEE standards 802.15.6. for WBAN. In the experiments, customized channel-sounding signals were applied to the human body using a battery-powered device with a ground-electrode size of 27x50 mm(2). The signals received after passage through the body were measured considering 30 kinds of measurement conditions determined by the body postures and locations of the transmitter and receiver. The operating frequencies of the transmission signals were varied up to 100 MHz. This work derives the minimum required lengths of symbol-codes based on analyses of channel-measured data in terms of measurement conditions, operating frequencies, and bandwidths of a receive-filter, to achieve a maximum data rate. This was done to ensure handling of intrinsic signal errors such as those by inter-symbol-interference, and to provide more reliable bit-error-rate performance in the human body channel, depending on the transmitter structures.