Ultrasound In-Body Communication with OFDM through Multipath Realistic Channels

Implanted medical devices need a reliable, low-energy and secure in-body communication link. Ultrasound wave propagation is promising over other techniques due to its lower body attenuation, inherent security and well-known health risks. While US communication systems have been developed for in-body communication, state-of-the-art systems fail to provide small-size solutions capable of operating under realistic channel conditions. This paper focuses on communication with small-scale (2 mm size) and omni-directional transducers (1.2 MHz center frequency), and discusses the high multipath delay in such channels. To cope with these channel characteristics, an ultrasound in-body optimized OFDM communication scheme is proposed and implemented. In experiments through real tissue, the modem achieves a bit error rate below 1e-4 until a throughput of 340 kbps across 10 cm of beef tissue.