Abstracts Health Sciences

Modulation techniques and channel assessment for galvanic coupled intrabody communications

by Fabián Abarca-Calderón

Intrabody Communications has emerged as a topic of interest for research due to its great potential to enable a new generation of healthcare devices. As a part of a whole ecosystem of biotelemetry, it remains as a 'missing link' between the sensors that collect the data from within our body and the connected applications that may help us better monitor our health.; This work focuses on the physical layer of an approach known as Galvanic Coupling. This technique applies a differential alternating field directly to the biological tissue with the help of a pair of electrodes, creating a current that propagates through and across tissues and is detected by another pair of electrodes. This method offers advantages regarding energy consumption, bit rate and hardware complexity compared to other methods.; The focus is, first, on the experimental assessment of the channel, resulting in its characterization in terms of noise, path gain and frequency response. Experimentation is made with porcine tissue, which presents similar dielectric properties compared to the human tissue. This method makes it possible for us to study inner tissues that otherwise would be difficult to access. The results provide us with more accurate channel parameters for simulation and design.; Secondly, the analysis and proposal of several M-ary Pulse-Based Modulation (PBM) schemes is made, using the Prolate Spheroidal Wave Functions (PSWF.) Their implementation and performance characteristics are evaluated, along with the commonly used Continuous Wave Modulation (CWM) schemes.; Finally, the synchronization and multiple access issues are addressed, as important components of most practical implementations. A scenario is studied with a central receiver and several single-hop satellite transmitters. Alternatives for a protocol are then proposed.