Theoretical Modeling and Analysis of Magnetic Induction Communication in Wireless Body Area Networks (WBANs)

Human activity recognition using magnetic induction-based motion signals and deep recurrent neural networks

“…The MI coils have a small radiation resistance, which means that the energy propagated to the far-field is negligible. As a result, multipath fading is not an issue, and the MI system can offer a much better quality of service (QoS) compared to Bluetooth-type systems 33,44,45 . The non-propagating magnetic field produced by the coils falls off proportional to r −3 instead of r −1 for radiating fields at a transmission distance r. Although the rapid decay limits the coverage range, it can be favorable in short-range applications such as WBANs 46 .…”

“…The signal generated by an MI coil attenuates as a function of frequency, channel medium, coils' geometry, location, and alignment (see Methods section) 33 . The non-propagating magnetic field is mainly affected by the permeability of the medium, which is close to the air for non-ferrous materials.…”

“…The MI channel condition remains constant even in an inhomogeneous lossy medium, such as around the human body 33,49 . For the frequency of up to 30 MHz, the dimension of the human body is relatively small compared to the wavelength, which makes the propagation and scattering effects insignificant 33 . The immunity of signal in this frequency range to the environment makes the forward voltage gain, S 21 , of the MI system only a function of coils' locations and alignments for a predefined coil geometry and operating frequency.…”

“…Due to the limitation of energy resources, the power management has become a critical issue in designing a WBAN. Since wireless communication consumes a considerable portion of the energy 30 , numerous studies have proposed and investigated low-power solutions [31][32][33][34] . The conventional state-of-the-art wireless sensor networks working in the vicinity of the human body adopt radio-wave propagation for signal transmission.…”

“…This technique is susceptible to the characteristics of the environment, and its signal experiences a high attenuation around a lossy medium, such as the human body. It results in higher power consumption, shorter battery life, and lower reliability 33,35,36 . Moreover, radio-wave propagation technologies are prone to interference with adjacent communication links since most of them, such as Bluetooth, operate at the busy 2.4 GHz, the industrial, scientific, and medical (ISM) band 37,38 .…”