A Novel Intrabody Communication\ud Transceiver for Biomedical\ud Applications

Intrabody communication (IBC) is a new physical layer defined in the recently ratified\ud wireless body area network (WBAN) IEEE 802.15.6 standard. The cable-free\ud IBC technology uses body tissue as a propagation medium instead of air. While recent\ud studies have shown a degradation of transmission signal for IBC between limb\ud segments, these degradations have yet to be quantified with respect to relative limb\ud positions. The current thesis investigates the influence of human movement on signal\ud attenuation during IBC considering limb joint effects within the transmission\ud frequency range 0.3-200 MHz. In-vivo experiments are conducted to determine the\ud effects of size, situations (flexed or extended), and locations (lower or upper limb) of\ud joints on the IBC. Results show that the presence of joints along the transmission\ud path causes high signal attenuation (up to 6.0 dB), the flexed limb exhibits 4.0 dB\ud less attenuation compared with extended one, and the lower limb joints (knee) shows\ud higher attenuation (2.0 dB) than upper limb joints, below 60 MHz. We propose a\ud new IBC circuit model explaining elbow joint effects. The presented model not only\ud takes the limb joint effects of the body into account but also considers the influence of\ud measurement equipment in higher frequency band thus predicting signal attenuation\ud behavior over wider frequency ranges. Results from the model simulation reveal that\ud the presence of limb joint within the signal transmission path causes an additional 1.0 to 5.2 dB loss at frequencies below 60 MHz for on-body channel length of 20 cm.\ud The simulation results suggest that the measurement equipment effects are negligible,\ud below 60 MHz. Finally, this work proposes transmitter and receiver architectures for\ud intrabody communication. A carrier-free scheme based on impulse radio (IR) for the\ud IBC (IR-IBC) is implemented on a FPGA. Results demonstrate data rates of up to\ud 1.56 Mbps achievable for the galvanic coupling IBC method