Intra-Body Communication and Networks:
Galvanic Coupling Intra-Body Communication Testbed
The Galvanic Coupling Intra-Body Communication (GC-IBC) testbed was designed to establish a uni-directional communication link through synthetic human tissue using the GC concept. This testbed has following objectives: (1) the ability to modify modulation schemes and other parameters for various communication scenarios, (2) real-time transmission of physiological data sets and images, (3) the measurement of BER at the receiver node, and (4) the comparison of the link quality results with other published works that invoke concepts from wireless communication theory and intra-body communication.
The GC-IBC testbed encompasses and controls all aspects of a traditional wireless communication system, including, but not limited to bit generation, automatic gain control, preamble insertion, frequency offset estimation and raised cosine filtering. We presented this framework alongside a MATLAB-based GUI, that allows the user to select various modulation schemes and other transmission parameters, for the link. The GUI at the Rx displays the BER rate and compares the real-time BER measurement to results from previous channel sounding experiments.
Galvanic Coupling Human Body Channel Modeling
This work is focused on channel characterization of the human body tissues considering the propagation of such electrical signals through it that carry data. Experiments were conducted using porcine tissue (in lieu of actual human tissue) with skin, fat and muscle layers in the frequency range of 100 kHz to 1 MHz. By utilizing single-carrier BPSK modulated Pseudorandom Noise Sequences, a correlative channel sounding system was implemented, leading to the following contributions: (1) measurements of the channel impulse and frequency response, (2) a noise analysis and capacity estimation, and (3) the comparison of results with existing models.
Results indicate that the channel response is relatively flat for the frequency range of interest, there exists no presence of multi-path fading, the noise can be approximated as additive white Gaussian, and the achievable capacity lies in the range of Mbps. The comparison of these experimental results with currently existing analytic channel models and experiments show a reasonable amount of accuracy for the chosen empirical modeling method.
Multi-Cast and Multi-Hop Communication Scheme
The work done in this project employs an in-depth signal reflection and refraction analysis of electromagnetic waves through human tissue boundaries (modeled as a lossy dielectric block with four tissue layers) were conducted, and the design of a combined multi-hop and multi-cast communication scheme for communication between implants was developed.