Distributed MAC and rate adaptation for ultrasonically networked implantable sensors

Abstract

Abstract-The use of miniaturized biomedical devices implanted in the human body and wirelessly internetworked is promising a significant leap forward in medical treatment of many pervasive diseases. Recognizing the well-understood limitations of traditional radio-frequency wireless communications in interconnecting devices within the human body, in this paper we propose to develop network protocols for implantable devices based on ultrasonic transmissions. We start off by assessing the feasibility of using ultrasonic propagation in human body tissues and by deriving an accurate channel model for ultrasonic intra-body communications. Then, we propose a new ultrasonic transmission and multiple access technique, which we refer to as Ultrasonic WideBand (UsWB). UsWB is based on the idea of transmitting information bits spread over very short pulses following a time-hopping pattern. The short impulse duration results in limited reflection and scattering effects, and its low duty cycle reduces the thermal and mechanical effects, which are detrimental for human health. We then develop a multiple access technique with distributed control to enable efficient simultaneous access by interfering devices based on minimal and localized information exchange and on measurements at the receiver only. Finally, we demonstrate the performance of UsWB through a multi-scale simulator that models the proposed communication system at the acoustic wave level, at the physical (bit) level, and at the network (packet) level.

Sonar inside your body: Prototyping ultrasonic intra-body sensor networks

“…Based on these observations, in [2] we proposed Ultrasonic WideBand (UsWB), a new impulse-radio inspired ultrasonic transmission and multiple access technique based on the idea of transmitting short information-bearing carrierless ultrasonic pulses, following a pseudo-random adaptive time-hopping pattern with a superimposed spreading code of adaptive length. Impulsive transmission and spread-spectrum encoding combat the effects of multipath and scattering and introduce waveform diversity among interfering transmissions.…”

“…Given the limitations of RF propagation, in [1], [2] we proposed and investigated the use of ultrasonic waves as an alternative carrier of information in human tissues. Lowfrequency acoustic waves (up to 100 kHz) have found application in underwater communications [5], while ultrasounds at higher frequencies are extensively used in medical imaging applications [6].…”

“…Based on these observations, in [2], we proposed Ultrasonic WideBand (UsWB), a new ultrasonic multipath-resilient physical and medium access control (MAC) layer integrated protocol. UsWB is based on the idea of transmitting short carrierless ultrasonic pulses following a pseudo-random adaptive time-hopping pattern, with a superimposed adaptive spreading code.…”

“…Given the well-understood limitations of radio frequency (RF) propagation in the human body, in our previous work we investigated the use of ultrasonic waves as an alternative physical carrier of information [1], and proposed Ultrasonic WideBand (UsWB), an ultrasonic multipath-resilient integrated physical and medium access control (MAC) layer protocol [2]. In this paper, we discuss the design and implementation of a software-defined testbed architecture for ultrasonic intra-body area networks, and propose the first experimental demonstration of the feasibility of ultrasonic communications in biological tissues.…”

Opto-ultrasonic communications in wireless body area nanonetworks

“…In [8], [9], we showed that ultrasonic waves have a strong potential to enable internetworking among devices implanted in the human body at communication ranges spanning from few µm to several cm; while in [10] the authors, based on consideration on the physics of ultrasound propagation, investigate the power requirements for acoustic communications between nanorobots across various distances and tissues. However, as of today and to best of our knowledge, no existing studies have explored the feasibility of ultrasonic wave generation and detection at the nanoscale for communication purposes.…”