Channel modeling and power consumption analysis for galvanic coupling intra-body communication

Abstract

Intra-body communication (IBC), using the human body as the channel to transmit data, has lower power consumption, less radiation, and easier linking than common wireless communication technologies such as Bluetooth, ZigBee, and ANT + . As a result, IBC is greatly suitable for body area network (BAN) applications, such as the medical and health care field. Furthermore, IBC can be implemented in wearable devices, including smart watches, sports bracelets, somatic game devices, and multimedia devices. However, due to the limited battery capacity of sensor nodes in a BAN, especially implanted sensor nodes, it is not convenient to charge or change the batteries. Thus, the energy effectiveness of the media access control (MAC) layer strongly affects the life span of the nodes and of the entire system. Certainly, analyzing MAC layer performance in a galvanic coupling IBC is of great importance for the overall system. To obtain the attenuation properties of IBC, in vivo experiments with seven volunteers were performed. Meanwhile, an equalizer was used to compensate the frequency distortion in consideration of frequency-selective fading characteristics of intra-body channels. In addition, a comparison of the bit error rates (BER) of different modulation methods was carried out to obtain the best modulation method. Then, the attenuation characteristics of intra-body channels were applied in a multi-node physiological signal monitor and transmission system. Finally, TDMA and CSMA/CA protocols were introduced to calculate the bit energy consumption of IBC in the practical scenario. With stable characteristics of the intra-body channels, QPSK with an equalizer had a better performance than the tests without an equalizer. As a result, the modulation method of FSK could achieve a lower BER in lower signal-to-noise ratio situations and an FSK method with TDMA for the IBC had the lowest energy consumption under different practical scenarios.

Wireless Body Sensor Communication Systems Based on UWB and IBC Technologies: State-of-the-Art and Open Challenges

“…However, for obtaining reliable results these measurements should be repeated using small battery-powered devices and tested on a large group of individuals, in order to analyze the influence of anthropometric properties of a subject. It is expected that in capacitive IB2OB and IB2IB channels an intersubject variability (anthropometrical and bioelectric properties of a subject) will have higher impact on measurement results than in the case of a capacitive OB2OB channel (for which it is almost negligible [ 13 ]), as is the case with galvanic IBC channels [ 15 , 180 , 201 ].…”

Past Results, Present Trends, and Future Challenges in Intrabody Communication

“…The measured attenuation was better when the subject was sitting compared to standing or walking, due to the difference in distance between the ground electrode and the external ground plane: the lower this distance is, the better the signal values are. Measurements of galvanic coupling IBC channel on 7 subjects were performed by Gao et al in [169,170]. It was shown that the thicker forearms had lower attenuation, which indicates that the main path of the IBC signals was muscle.…”

“…In summary, since in the galvanic coupling the signal is confined to the human body, for the same measuring setup the communication is mainly influenced by the anthropometrical and bioelectric properties of a subject, that is, intersubject variability [29,151,170]. For example, for IBC units placed on the arm these characteristics are arm diameter, tissue thicknesses (such as skin, fat, and muscle), tissue anisotropy, presence of joints in the communication channel, and so on [29,38,93,174].…”

A Low-Cost Electronic System for Human-Body Communication

“…As we previously stated, in this work we focus on galvanic coupling communication. From the literature, one can observe different studies related to galvanic communication [9][10][11][12][13][14][15]. The prominent and important problem addressed by the majority of these studies lies in modeling the body as a physical environment for the propagation of signals over short distances (up to 20 cm), performing an empirical analysis of the human tissue properties.…”

“…However, these devices are not suitable for data analysis [2,12]. When the applications handle specific data, such as medical or encrypted data [3], VNAs are replaced by data generation and acquisition systems [9,[12][13][14][15]. Reducing the size of this set is a challenge due to the transformers' physical characteristics.…”