Impulse response analysis of an ultrasonic human body channel

Abstract

Ultrasounds have been successfully and safely employed in underwater communications and for health diagnosis in the last 60 years because of their good performance in environments with high water concentration. Recently it has been proposed also to employ them for supporting intra-body communications; however exploitation of ultrasounds inside the body calls for a deep understanding of their features and a full characterization of the impulse response inside these challenging channels. In this paper we provide a complete experimental characterization of the impulse response inside a human body communication channel, composed for more than 65-70\% of water. To this purpose we developed a testbed which employs a human phantom of ballistic gel to emulate the human body propagation features and performed a set of measurements to fully discuss the channel behavior as a function of different parameters such as the employed frequency, the channel composition and the distance. Our results show that, it is possible to clearly identify the three main components generated by multipath propagation inside the human phantom, i.e. the direct, lateral and reflected waves. Also, it is possible to observe that the excess delay which measures the time elapsed between the first and the last arriving waves, increases approximately as 10 $\mu$s per cm. Our analysis provides interesting has strong implications on the design of communication protocols for intra-body scenarios.

Experimental Channel Characterization of Human Body Communication Based on Measured Impulse Response

“…Methods based on impulse response show some potential for filling this gap, but, while this approach has been largely employed to characterize wireless channels over the air [18], limited effort has been spent so far to model IBC channels through impulse response methods [19]. Some studies were conducted only on CC in wearable configuration [20]- [23] and a few others on GC [17], [24].…”

An Energy-Efficient Carrier Synchronization Method for Galvanic Coupling Intra-Body Communication

“…Anyhow, they are unable to model essential properties of wireless channels, such as multi-path delay spread and amplitude fading statistics, that need to be taken into account when designing a communication system [17]. Methods based on impulse response have a potential to fill this gap; however, while this approach has been largely employed to characterize wireless channels over the air [18], only limited effort has been spent so far to model IBC channels through impulse response methods [17], [19], [20]. In this work we use a correlative channel sounding method [17], [18] employing pseudorandom noise (PN) sequences to evaluate the GC channel impulse response through experimental measurements.…”

“…(a) The integer delay µ is estimated through the known preamble sequence p * (kT s ) at the receiver, multiplied by the received sequence after counter-rotation y(t) as given in (17). (b) Then, the fractional delay ϵ (symbol delay) is estimated with the Wiener filter in (19), exploiting the crosscorrelation between the known transmitted preamble p and the counter-rotated received one y p , that is shifted by the amount μ.…”

Electromagnetic Nanonetworks Beyond 6G: From Wearable and Implantable Networks to On-Chip and Quantum Communication

“…Ultrasounds or acoustic waves at ultrasonic frequencies (i.e., above the audible limit of 20 kHz), have also been discussed in the context of nanonetworks [96], [97]. NEMS can be utilized to both generate and detect pressure waves at the nano and micro scales.…”

“…This requires a careful revisit of not only the channel models, as thermal noise is reduced dramatically, but also of the RF circuit design, now that most RF device non-idealities are largely attenuated. Internet of NanoThings Wireless Networks within Package Quantum Computing Optical [111], [112], [115] [130], [162] [160] THz [85], [121] [16], [67], [73], [131], [163] [137] mmWave [164] [68], [129], [163], [165]- [169] [17] Microwave [122], [123], [170], [171] N/A [158], [159], [161] Non-Radiative [96], [97] N/A N/A…”