Abstract
The Internet of Bodies (IoB) is an imminent extension of the vast
Internet of things (IoT) domain, where wearable, ingestible, injectable,
and implantable smart objects form a network in, on, and around the
human body. Even though on-body IoB communications are required to occur
within very close proximity of the human body, on-body wireless radio
frequency (RF) IoB devices unnecessarily extend the coverage range
beyond the human body due to their radiative nature. This eventually
reduces energy efficiency, causes co-existence and interference issues,
and exposes sensitive personal data to security threats. Alternatively,
capacitive body channel communications (BCC) exhibit much less signal
leakage by confining signal transmission to the human body and
experience substantially less propagation loss than RF systems as body
tissues has better conductivity than surrounding air. Furthermore, the
BCC band (10-100 MHz) decouples the transceiver size from the carrier
wavelength, eliminating the need for complex and power-hungry radio
front-ends. Therefore, capacitive BCC is a key enabler to reach the
ultimate design goals of ultra-low-power, high throughput, and small
form-factor IoB devices. Albeit these attractive features, the
communication and networking aspects of the capacitive BCC are not
thoroughly explored yet. This paper is the first to model orthogonal and
non-orthogonal body channel access schemes with or without cooperation
among the IoB nodes. In order to address the quality of service (QoS)
demand scenarios of different IoB applications, we present and formulate
max-min rate, max-sum rate, and QoS sufficient operational regimes, then
provide solution methodologies for optimal power and phase time
allocations. Extensive numerical results are analyzed to compare the
performance of orthogonal and non-orthogonal schemes with and without
cooperation for various design parameters under prescribed QoS regimes.