A Review on Human Body Communication: Signal Propagation Model, Communication Performance, and Experimental Issues
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paper_title: Investigation into off-body links for wrist mounted antennas in bluetooth systems

paper_content:

This paper presents a detailed investigation into off-body links for wrist mounted Bluetooth Low Energy (BLE) devices for an indoor environment and revolves around three low profile antennas (microstrip patch, printed monopole and external monopole). It studies the received signal strength across different usage scenarios and obstructions such as body shadow, wall and ceiling through measurement campaigns carried out in a 2-storey house. It is observed that RSSIs show little variation from the mean value at any position in a given room of the house. In the living room, the average RSSI for patch, printed and external monopole is close to −61,-73 and −61 dBm respectively. The study describes the effect of usual obstructions such as wall and ceiling to off-body links and shows that the range of RSSI for any antenna (30 dBm at P=0.5 for Patch Antenna) is bounded at one end by the CDF of wall plus body shadow and at the other end by CDF of Line of Sight (LOS). The effect of body shadowing is studied in greater detail. It is observed that the microstrip patch antenna in LOS, under a ceiling and behind a wall, drops by approximately 15dB, 5dB and 10dB at P=0.4 when it goes into body shadow. The study also suggests that the Access Point (AP) on the ceiling provides better off-body links as compared to it in the adjacent room. The study compares the overall performance of the three antennas across all possible usage scenarios, obstructions & polarizations and concludes that the external monopole and patch antenna performs better than printed monopole by approximately 10–13 dBm. Finally, the study shows the variation of Packet Error Rate (PER) with RSSI and determines threshold values of RSSI for acceptable PERs, for reliable and robust applications.
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paper_title: A Survey on Intrabody Communications for Body Area Network Applications

paper_content:

The rapid increase in healthcare demand has seen novel developments in health monitoring technologies, such as the body area networks (BAN) paradigm. BAN technology envisions a network of continuously operating sensors, which measure critical physical and physiological parameters e.g., mobility, heart rate, and glucose levels. Wireless connectivity in BAN technology is key to its success as it grants portability and flexibility to the user. While radio frequency (RF) wireless technology has been successfully deployed in most BAN implementations, they consume a lot of battery power, are susceptible to electromagnetic interference and have security issues. Intrabody communication (IBC) is an alternative wireless communication technology which uses the human body as the signal propagation medium. IBC has characteristics that could naturally address the issues with RF for BAN technology. This survey examines the on-going research in this area and highlights IBC core fundamentals, current mathematical models of the human body, IBC transceiver designs, and the remaining research challenges to be addressed. IBC has exciting prospects for making BAN technologies more practical in the future.
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paper_title: A Mobility Enabled Inpatient Monitoring System Using a ZigBee Medical Sensor Network

paper_content:

This paper presents a ZigBee In-Patient Monitoring system embedded with a new ZigBee mobility management solution. The system enables ZigBee device mobility in a fixed ZigBee network. The usage, the architecture and the mobility framework are discussed in details in the paper. The evaluation shows that the new algorithm offers a good efficiency, resulting in a low management cost. In addition, the system can save lives by providing a panic button and can be used as a location tracking service. A case study focused on the Princes of Wales Hospital in Hong Kong is presented and findings are given. This investigation reveals that the developed mobile solutions offer promising value-added services for many potential ZigBee applications.
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paper_title: The design of dual radio ZigBee homecare gateway for remote patient monitoring

paper_content:

A Dual Radio ZigBee Homecare Gateway (DRZHG) has been proposed and implemented to support remote patient monitoring. The novelty of DR-ZHG is two-fold. Firstly, it increases the transmission data rate of ZigBee. The Dual Radio ZigBee design furnishes low latency and highly accurate telehealth service at home. Secondly, the zero-configuration design of the DR-ZHG offers the most user friendly telehealth service to elderly people and long-terms patients. Analysis reveals that, for streaming data devices, the network depth should be confined to three (3) in a ZigBee tree network. As for polling data devices, it is analyzed that nine (9) sensors can be supported in a single hop communication. To align with the maximum hop count of three (3) for streaming devices, seven (7) polling devices can be accommodated. In summary, the developed DR-ZHG supports seven (7) polling service sensors and one (1) streaming service senor. Such a gateway meets the general latency standard of 2s for telemedicine services as stipulated by U.S. NIST.
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paper_title: A Continuous Biomedical Signal Acquisition System Based on Compressed Sensing in Body Sensor Networks

paper_content:

The emerging compressed sensing (CS) holds considerable promise for continuously acquiring biomedical signals in body sensor networks (BSNs), which enables nodes to employ a much lower sampling rate than Nyquist while still able to accurately reconstruct signals. CS-based BSNs are expected to significantly enhance the quality of healthcare and improve the ability of prevention, early diagnosis, and treatment of chronic diseases. However, existing BSNs are still unable to support long-term monitoring in healthcare, as well as providing an energy-efficient low communication burden and inexpensive scheme. Capitalizing on the sparsity of biomedical signals in transfer domains, this paper develops a continuous biomedical signal acquisition system, which explores a sparsification model to find the sparse representation of biomedical signals. The sparsified measurements of signals are wirelessly transmitted to a fusion center through BSNs. Meanwhile, a weighted group sparse reconstruction algorithm is proposed to accurately reconstruct the signals at the fusion center. Simulation results show that, on random sampling over BSN, the proposed group sparse algorithm shows good efficiency, strong stability, and robustness.
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paper_title: Ultra-wideband channel model for communication around the human body

paper_content:

Using ultra-wideband (UWB) wireless sensors placed on a person to continuously monitor health information is a promising new application. However, there are currently no detailed models describing the UWB radio channel around the human body making it difficult to design a suitable communication system. To address this problem, we have measured radio propagation around the body in a typical indoor environment and incorporated these results into a simple model. We then implemented this model on a computer and compared experimental data with the simulation results. This paper proposes a simple statistical channel model and a practical implementation useful for evaluating UWB body area communication systems.
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paper_title: Galvanic Coupling Transmission in Intrabody Communication: A Finite Element Approach

paper_content:

Galvanic coupling in intrabody communication (IBC) is a technique that couples low-power and low-frequency voltages and currents into the human body, which acts as a transmission medium, and thus constitutes a promising approach in the design of personal health devices. Despite important advances being made during recent years, the investigation of relevant galvanic IBC parameters, including the influence of human tissues and different electrode configurations, still requires further research efforts. The objective of this work is to disclose knowledge into IBC galvanic coupling transmission mechanisms by using a realistic 3-D finite element model of the human arm. Unlike other computational models for IBC, we have modeled the differential configuration of the galvanic coupling as a four-port network in order to analyze the electric field distribution and current density through different tissues. This has allowed us to provide an insight into signal transmission paths through the human body, showing them to be considerably dependent on variables such as frequency and inter-electrode distance. In addition, other important variables, for example bioimpedance and pathloss, have also been analyzed. Finally, experimental measurements were also carried out for the sake of validation, demonstrating the reliability of the model to emulate in general forms some of the behaviors observed in practice.
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paper_title: A Health-IoT Platform Based on the Integration of Intelligent Packaging, Unobtrusive Bio-Sensor, and Intelligent Medicine Box

paper_content:

In-home healthcare services based on the Internet-of-Things (IoT) have great business potential; however, a comprehensive platform is still missing. In this paper, an intelligent home-based platform, the iHome Health-IoT, is proposed and implemented. In particular, the platform involves an open-platform-based intelligent medicine box (iMedBox) with enhanced connectivity and interchangeability for the integration of devices and services; intelligent pharmaceutical packaging (iMedPack) with communication capability enabled by passive radio-frequency identification (RFID) and actuation capability enabled by functional materials; and a flexible and wearable bio-medical sensor device (Bio-Patch) enabled by the state-of-the-art inkjet printing technology and system-on-chip. The proposed platform seamlessly fuses IoT devices (e.g., wearable sensors and intelligent medicine packages) with in-home healthcare services (e.g., telemedicine) for an improved user experience and service efficiency. The feasibility of the implemented iHome Health-IoT platform has been proven in field trials.
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paper_title: Design and Optimization of the Extended True Single-Phase Clock-Based Prescaler

paper_content:

The power consumption and operating frequency of the extended true single-phase clock (E-TSPC)-based frequency divider is investigated. The short-circuit power and the switching power in the E-TSPC-based divider are calculated and simulated. A low-power divide-by-2/3 unit of a prescaler is proposed and implemented using a CMOS technology. Compared with the existing design, a 25% reduction of power consumption is achieved. A divide-by-8/9 dual-modulus prescaler implemented with this divide-by-2/3 unit using a 0.18-mum CMOS process is capable of operating up to 4 GHz with a low-power consumption. The prescaler is implemented in low-power high-resolution frequency dividers for wireless local area network applications
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paper_title: Electric Field Distributions of Wearable Devices Using the Human Body as a Transmission Channel

paper_content:

Recently, wearable devices which use the human body as a transmission channel have been developed. However, there has been a lack of information related to the transmission mechanism of such devices in the physical layer. Electromagnetic communication trials using the human body as a transmission medium have more than a decade's history. However, most of the researches have been conducted by researchers who just want to utilize the fact and practically no physical mechanisms have been researched until recently. Hence, in this paper, the authors propose some calculation models of the human body equipped with the wearable devices by using the finite difference time domain (FDTD) method. Moreover, a biological tissue-equivalent solid phantom is utilized to show the validity of the calculation. From these investigations, the authors determine the transmission mechanism of the wearable devices using the human body as a transmission channel.
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paper_title: A Wide-Band Power-Efficient Inductive Wireless Link for Implantable Microelectronic Devices Using Multiple Carriers

paper_content:

This paper presents a novel inductive link for wireless transmission of power and data to biomedical implantable microelectronic devices using multiple carrier signals. Achieving higher data bandwidth without compromising the power efficiency is the driving force behind using multiple separate carriers. Two separate pairs of coils have been utilized for inductive power and forward data transmission, plus a pair of miniature antennas for back telemetry. One major challenge, however, is to minimize the interference among these carriers especially on the implantable side, where size and power are highly limited. Planar power coils with spiral shape are optimized in geometry to provide maximum coupling coefficient k. The data coils are designed rectangular in shape and wound across the power coils diameter to be oriented perpendicular to the power coil planes. The goal is to maximize data coils direct coupling, while minimize their cross-coupling with the power coils. The effects of coils geometry, orientation, relative distance, and misalignments on the coupling coefficients have been modeled and experimentally evaluated.
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paper_title: Photoplethysmography-Based Heart Rate Monitoring in Physical Activities via Joint Sparse Spectrum Reconstruction

paper_content:

Goal: A new method for heart rate monitoring using photoplethysmography (PPG) during physical activities is proposed. Methods : It jointly estimates the spectra of PPG signals and simultaneous acceleration signals, utilizing the multiple measurement vector model in sparse signal recovery. Due to a common sparsity constraint on spectral coefficients, the method can easily identify and remove the spectral peaks of motion artifact (MA) in the PPG spectra. Thus, it does not need any extra signal processing modular to remove MA as in some other algorithms. Furthermore, seeking spectral peaks associated with heart rate is simplified. Results : Experimental results on 12 PPG datasets sampled at 25 Hz and recorded during subjects’ fast running showed that it had high performance. The average absolute estimation error was 1.28 beat/min and the standard deviation was 2.61 beat/min. Conclusion and Significance : These results show that the method has great potential to be used for PPG-based heart rate monitoring in wearable devices for fitness tracking and health monitoring.
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paper_title: Ultra low power cmos phase-locked loop frequency synthesizers

paper_content:

ACKNOWLEDGMENTS AUTHOR’S PUBLICATIONS TABLE OF CONTENTS LIST OF FIGURES LIST OF TABLES CHAPTER
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paper_title: Analysis and Optimization of Spiral Circular Inductive Coupling Link for Bio-Implanted Applications on Air and within Human Tissue

paper_content:

The use of wireless communication using inductive links to transfer data and power to implantable microsystems to stimulate and monitor nerves and muscles is increasing. This paper deals with the development of the theoretical analysis and optimization of an inductive link based on coupling and on spiral circular coil geometry. The coil dimensions offer 22 mm of mutual distance in air. However, at 6 mm of distance, the coils offer a power transmission efficiency of 80% in the optimum case and 73% in the worst case via low input impedance, whereas, transmission efficiency is 45% and 32%, respectively, via high input impedance. The simulations were performed in air and with two types of simulated human biological tissues such as dry and wet-skin using a depth of 6 mm. The performance results expound that the combined magnitude of the electric field components surrounding the external coil is approximately 98% of that in air, and for an internal coil, it is approximately 50%, respectively. It can be seen that the gain surrounding coils is almost constant and confirms the omnidirectional pattern associated with such loop antennas which reduces the effect of non-alignment between the two coils. The results also show that the specific absorption rate (SAR) and power loss within the tissue are lower than that of the standard level. Thus, the tissue will not be damaged anymore.
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paper_title: Sensor requirements for activity recognition on smart watches

paper_content:

The new generation of watches is smart. Smart watches are connected to the internet and provide sensor functionality that allows an enhanced human-computer-interaction. Smart watches provide a gesture interaction and a permanent monitoring of physical activities. In comparison to other electronic home consumer devices with integrated sensors, Smart watches provide monitoring data for 24h per day, many watches are water resistant and can be worn constantly. The integrated sensors are varying in performance and are not intended to distinguish between different states of activity and inactivity. This paper reports on identified requirements on sensors of smart watches for detection of activity, inactivity as well as sleep detection. Hereby a new measurement quantity is introduced and applications of heart beat detection or wearing situation are presented.
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paper_title: A low-power all-digital GFSK demodulator with robust clock data recovery

paper_content:

This paper presents an all-digital Gaussian frequency shift keying (GFSK) demodulator with robust clock data recovery (CDR) for low-intermediate-frequency (low-IF) receivers in wireless sensor networks (WSN). The proposed demodulator can detect and adapt to the intermediate frequency of the received signal automatically. In addition, the CDR can tolerate the frequency deviation of the input clock. An implementation of the demodulator with CDR is realized with HJTC 0.18 ¼m CMOS technology. The chip is designed for GFSK signals with a center frequency of 200 kHz, a modulation index of 1 and a data rate of 100 kbps. Experimental results show that the chip consumes 0.53 mA from a 1.8 V power supply, and only a 11 dB input signal to noise ratio (SNR) is required for 10-3 bit error rate (BER). The tolerance range for IF offset is \pm12.5% at 11 dB input SNR, and the CDR can tolerate frequency deviation of the input clock of \pm0.1%.
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paper_title: Security and privacy for implantable medical devices

paper_content:

Protecting implantable medical devices against attack without compromising patient health requires balancing security and privacy goals with traditional goals such as safety and utility. Implantable medical devices monitor and treat physiological conditions within the body. These devices - including pacemakers, implantable cardiac defibrillators (ICDs), drug delivery systems, and neurostimulators - can help manage a broad range of ailments, such as cardiac arrhythmia, diabetes, and Parkinson's disease. IMDs' pervasiveness continues to swell, with upward of 25 million US citizens currently reliant on them for life-critical functions. Growth is spurred by geriatric care of the aging baby-boomer generation, and new therapies continually emerge for chronic conditions ranging from pediatric type 1 diabetes to anorgasmia and other sexual dysfunctions. Moreover, the latest IMDs support delivery of telemetry for remote monitoring over long-range, high-bandwidth wireless links, and emerging devices will communicate with other interoperating IMDs.
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paper_title: Propagation characteristics of intra-body communications for body area networks

paper_content:

Body area networks (BAN) will become increasingly important in the future personal communication systems. We believe that intra-body communications (IBC) based on near field electromagnetic waves is a suitable solution for BAN. This paper presents experimental measurements of the frequency and time domain responses in order to investigate the transmission characteristics of the human body as a conductor of low power high frequency radio signals (up to 3GHz). In the measurements, several distances between transmitter and receiver (up to a long distance from the head to the foot) and six test people (to study the possible variation results due to physiological body effects) have been considered. Besides analyzing the intra-body channel response, we also aim to define a suitable frequency range for IBC. Finally, this paper also presents an initial evaluation study of several digital modulation schemes in order to investigate the optimal technique for IBC.
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paper_title: The dielectric properties of biological tissues: I. Literature survey

paper_content:

The dielectric properties of tissues have been extracted from the literature of the past five decades and presented in a graphical format. The purpose is to assess the current state of knowledge, expose the gaps there are and provide a basis for the evaluation and analysis of corresponding data from an on-going measurement programme.
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paper_title: The specific resistance of biological material—A compendium of data for the biomedical engineer and physiologist

paper_content:

The paper traces the history of, and tabulates determinations of the electrical resistivity of blood, other body fluids, cardiac muscle, skeletal muscle, lung, kidney, liver, spleen, pancreas, nervous tissue, fat, bone, and other miscellaneous tissues. Where possible, the conditions of measurement are given.
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paper_title: The dielectric properties of biological tissues: II. Measurements in the frequency range 10 Hz to 20 GHz

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Three experimental techniques based on automatic swept-frequency network and impedance analysers were used to measure the dielectric properties of tissue in the frequency range 10 Hz to 20 GHz. The technique used in conjunction with the impedance analyser is described. Results are given for a number of human and animal tissues, at body temperature, across the frequency range, demonstrating that good agreement was achieved between measurements using the three pieces of equipment. Moreover, the measured values fall well within the body of corresponding literature data.
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paper_title: The dielectric properties of biological tissues: III. Parametric models for the dielectric spectrum of tissues.

paper_content:

A parametric model was developed to describe the variation of dielectric properties of tissues as a function of frequency. The experimental spectrum from 10 Hz to 100 GHz was modelled with four dispersion regions. The development of the model was based on recently acquired data, complemented by data surveyed from the literature. The purpose is to enable the prediction of dielectric data that are in line with those contained in the vast body of literature on the subject. The analysis was carried out on a Microsoft Excel spreadsheet. Parameters are given for 17 tissue types.
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paper_title: A Self-Adaptive Capacitive Compensation Technique for Body Channel Communication

paper_content:

In wireless body area network, capacitive-coupling body channel communication (CC-BCC) has the potential to attain better energy efficiency over conventional wireless communication schemes. The CC-BCC scheme utilizes the human body as the forward signal transmission medium, reducing the path loss in wireless body-centric communications. However, the backward path is formed by the coupling capacitance between the ground electrodes (GEs) of transmitter (Tx) and receiver (Rx), which increases the path loss and results in a body posture dependent backward impedance. Conventional methods use a fixed inductor to resonate with the backward capacitor to compensate the path loss, while it's not effective in compensating the variable backward impedance induced by the body movements. In this paper, we propose a self-adaptive capacitive compensation (SACC) technique to address such a problem. A backward distance detector is introduced to estimate the distance between two GEs of Tx and Rx, and a backward capacitance model is built to calculate the backward capacitance. The calculated backward capacitance at varying body posture is compensated by a digitally controlled tunable inductor (DCTI). The proposed SACC technique is validated by a prototype CC-BCC system, and measurements are taken on human subjects. The measurement results show that 9dB–16 dB channel enhancement can be achieved at a backward path distance of 1 cm-10 cm.
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paper_title: Electric-Field Intrabody Communication Channel Modeling With Finite-Element Method

paper_content:

Electric-field intrabody communication (EF-IBC) is a promising new scheme for the data exchange among wearable biomedical sensors. It uses the body as the signal transmission media. Compared with existing body area network (BAN) schemes, EF-IBC can achieve higher data rate with less transmission power. Until now, the detailed EF-IBC channel mechanism is not well understood. In this work, finite-element method (FEM) is utilized for the first time to investigate the EF-IBC channel. A circuit-coupled FEM model is established for the EF-IBC channel. The FEM model is extensively verified by experimental measurements. The new physical model enables the revelation of characteristics and effects of different components in the EF-IBC channel. The FEM investigation finds that the capacitive return path is critical to the characteristics of the EF-IBC channel. Parameters of the capacitive return path are quantitatively measured. The investigation also finds that the body plays an important role to the return path capacitance. The forward body path can be well modeled by a cascade of π-shaped circuits. Based on the FEM model of the EF-IBC channel, a simplified circuit model is derived to provide an efficient tool for the transceiver design.
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paper_title: The Human Body Characteristics as a Signal Transmission Medium for Intrabody Communication

paper_content:

The human body characteristics as a signal transmission medium are studied for the application to intrabody communication. The measurements of the body channel cover the frequency range from 100 kHz to 150 MHz and the distance on the body up to 1.2 m. A distributed RC model is developed to analyze the large variation of the channel properties according to the frequency and channel length. The simulation results using the channel model match well with the measurements in both the frequency and time domains. The effect of the ground plane to the body channel transceivers is also investigated and an empirical formula for the minimum ground size is obtained. Finally, the amount of the electromagnetic radiation due to the body antenna effect is measured. With regards to the Federal Communications Commission regulations, the proper frequency range for the intrabody communication is determined to satisfy given bit error rate requirements
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paper_title: An Investigation on Ground Electrodes of Capacitive Coupling Human Body Communication

paper_content:

Utilizing the body surface as the signal transmission medium, capacitive coupling human body communication (CC-HBC) can achieve a much higher energy efficiency than conventional wireless communications in future wireless body area network (WBAN) applications. Under the CC-HBC scheme, the body surface serves as the forward signal path, whereas the backward path is formed by the capacitive coupling between the ground electrodes (GEs) of transmitter (TX) and receiver (RX). So the type of communication benefits from a low forward loss, while the backward loss depending on the GE coupling strength dominates the total transmission loss. However, none of the previous works have shown a complete research on the effects of GEs. In this paper, all kinds of GE effects on CC-HBC are investigated by both finite element method (FEM) analysis and human body measurement. We set the TX GE and RX GE at different heights, separation distances, and dimensions to study the corresponding influence on the overall signal transmission path loss. In addition, we also investigate the effects of GEs with different shapes and different TX-to-RX relative angles. Based on all the investigations, an analytical model is derived to evaluate the GE related variations of channel loss in CC-HBC.
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paper_title: Electric Field Distributions of Wearable Devices Using the Human Body as a Transmission Channel

paper_content:

Recently, wearable devices which use the human body as a transmission channel have been developed. However, there has been a lack of information related to the transmission mechanism of such devices in the physical layer. Electromagnetic communication trials using the human body as a transmission medium have more than a decade's history. However, most of the researches have been conducted by researchers who just want to utilize the fact and practically no physical mechanisms have been researched until recently. Hence, in this paper, the authors propose some calculation models of the human body equipped with the wearable devices by using the finite difference time domain (FDTD) method. Moreover, a biological tissue-equivalent solid phantom is utilized to show the validity of the calculation. From these investigations, the authors determine the transmission mechanism of the wearable devices using the human body as a transmission channel.
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paper_title: Channel Modeling of Miniaturized Battery-Powered Capacitive Human Body Communication Systems

paper_content:

Objective: The purpose of this contribution is to estimate the path loss of capacitive human body communication (HBC) systems under practical conditions. Methods: Most prior work utilizes large grounded instruments to perform path loss measurements, resulting in overly optimistic path loss estimates for wearable HBC devices. In this paper, small battery-powered transmitter and receiver devices are implemented to measure path loss under realistic assumptions. A hybrid electrostatic finite element method simulation model is presented that validates measurements and enables rapid and accurate characterization of future capacitive HBC systems. Results: Measurements from form-factor-accurate prototypes reveal path loss results between 31.7 and 42.2 dB from 20 to 150 MHz. Simulation results matched measurements within 2.5 dB. Comeasurements using large grounded benchtop vector network analyzer (VNA) and large battery-powered spectrum analyzer (SA) underestimate path loss by up to 33.6 and 8.2 dB, respectively. Measurements utilizing a VNA with baluns, or large battery-powered SAs with baluns still underestimate path loss by up to 24.3 and 6.7 dB, respectively. Conclusion: Measurements of path loss in capacitive HBC systems strongly depend on instrumentation configurations. It is thus imperative to simulate or measure path loss in capacitive HBC systems utilizing realistic geometries and grounding configurations. Significance: HBC has a great potential for many emerging wearable devices and applications; accurate path loss estimation will improve system-level design leading to viable products.
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paper_title: Intra-body data transmission for the personal area network

paper_content:

Intra-body communication is a wireless means of exchanging information within a personal area network (PAN) between wearable electronic sensors and devices. The feasibility of intra-body communication is confirmed through several experiments on signal propagation within the human body, and a human phantom is designed and used to obtain reproducible results over repeated experiments. Based on the results of these experiments, a prototype transmission system is constructed using aluminum electrodes powered by 3 V DC and operating in the 10.7 MHz frequency modulation (FM) band. This prototype is demonstrated to be capable of transmitting analog signals through the human subjects in the presence of external noise. Digital data transmission at 9600 bps is also achieved using newly fabricated 10.7 MHz frequency shift keying (FSK) transmitter and receiver devices. The carrier frequency of 10.7 MHz is the intermediate frequency of FM radio receivers, meaning that the proposed system can make use of a wide selection of inexpensive, commercial radio frequency devices.
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paper_title: Distributed Circuit Modeling of Galvanic and Capacitive Coupling for Intrabody Communication

paper_content:

Modeling of intrabody communication (IBC) entails the understanding of the interaction between electromagnetic fields and living tissues. At the same time, an accurate model can provide practical hints toward the deployment of an efficient and secure communication channel for body sensor networks. In the literature, two main IBC coupling techniques have been proposed: galvanic and capacitive coupling. Nevertheless, models that are able to emulate both coupling approaches have not been reported so far. In this paper, a simple model based on a distributed parameter structure with the flexibility to adapt to both galvanic and capacitive coupling has been proposed. In addition, experimental results for both coupling methods were acquired by means of two harmonized measurement setups. The model simulations have been subsequently compared with the experimental data, not only to show their validity but also to revise the practical frequency operation range for both techniques. Finally, the model, along with the experimental results, has also allowed us to provide some practical rules to optimally tackle IBC design.
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paper_title: A very low-power consumption wireless ECG monitoring system using body as a signal transmission medium

paper_content:

A very low-power consumption wireless system for monitoring ECG (electrocardiogram) is proposed. It consists of an ECG detector/transmitter located on the chest and the relay transmitter placed at the wrist. Between the detector part and the relay transmitter, the signal is send as the AC micro current flows through the tissue of the body. Since this method achieves very low-power signal transmission of about 8 /spl mu/W (400 mV/sub RMS//spl times/20 /spl mu/A/sub RMS/), the system can be driven by a very small power source like a thin film battery. A similar wireless transmission method can be applied for other medical signal/data sensing micro systems sharing the same relay transmitter.
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paper_title: Galvanic Coupling Transmission in Intrabody Communication: A Finite Element Approach

paper_content:

Galvanic coupling in intrabody communication (IBC) is a technique that couples low-power and low-frequency voltages and currents into the human body, which acts as a transmission medium, and thus constitutes a promising approach in the design of personal health devices. Despite important advances being made during recent years, the investigation of relevant galvanic IBC parameters, including the influence of human tissues and different electrode configurations, still requires further research efforts. The objective of this work is to disclose knowledge into IBC galvanic coupling transmission mechanisms by using a realistic 3-D finite element model of the human arm. Unlike other computational models for IBC, we have modeled the differential configuration of the galvanic coupling as a four-port network in order to analyze the electric field distribution and current density through different tissues. This has allowed us to provide an insight into signal transmission paths through the human body, showing them to be considerably dependent on variables such as frequency and inter-electrode distance. In addition, other important variables, for example bioimpedance and pathloss, have also been analyzed. Finally, experimental measurements were also carried out for the sake of validation, demonstrating the reliability of the model to emulate in general forms some of the behaviors observed in practice.
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paper_title: A new technique for transmission of signals from implantable transducers

paper_content:

To reduce space requirements for implant electronics in in vivo telemetry applications, the purpose of this project was to develop and test a new data transmission method that utilizes the ionic properties of bodily fluids as the transmission medium. Motivated by an interest in using the new method to transmit information from a sensor which measures tension in anterior cruciate ligament (ACL) grafts, a sine wave was injected into a cadaver leg using platinum electrodes implanted into the lateral femoral epicondyle. The signal was detected by electromyogram (EMG) surface electrodes. The effect of transmission frequency, the current injected, interelectrode separation, distance of the electrodes from the joint line, and the surface of electrode placement on the signal attenuation was studied. The logarithmic relation between attenuation and frequency was constant from 2 kHz until 10 kHz. For frequencies above 10 kHz, the attenuation increased linearly at the rate of 1 dB/octave. Attenuation was inversely sensitive to both current and interelectrode separation with larger separations and currents giving less attenuation. Attenuation was significantly less for the lateral thigh surface than for the anterior surface and increased with increasing distance from the joint line for both surfaces. For the application of interest here, suitable values of transmission variables to avoid the possible negative consequences of injecting current into living tissue are a current of 3 mA injected at a frequency of 37 kHz. The values of reception variables for minimum attenuation are wide interelectrode separation (5 cm) with the electrodes placed 5 cm proximal of the joint line on the lateral surface of the thigh. With the exception of the surface which is application dependent, these values of the reception variables should also be appropriate for other applications.
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paper_title: A Review on Telemedicine-Based WBAN Framework for Patient Monitoring

paper_content:

Abstract Objective: In this article, we describe the important aspects like major characteristics, research issues, and challenges with body area sensor networks in telemedicine systems for patient monitoring in different scenarios. Present and emerging developments in communications integrated with the developments in microelectronics and embedded system technologies will have a dramatic impact on future patient monitoring and health information delivery systems. The important challenges are bandwidth limitations, power consumption, and skin or tissue protection. Materials and Methods: This article presents a detailed survey on wireless body area networks (WBANs). Results and Conclusions: We have designed the framework for integrating body area networks on telemedicine systems. Recent trends, overall WBAN-telemedicine framework, and future research scope have also been addressed in this article.
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paper_title: Development and performance analysis of an intra-body communication device

paper_content:

Personal area networks would benefit from a wireless communication system in which a variety of information could be exchanged through wearable electronic devices and sensors. Intra-body communication using the human body as the transmission medium enables wireless communication without transmitting radio waves through the air. A human arm phantom is designed and used to reduce uncertainty in experiments with the human body. The phantom exhibits transmission characteristics similar to those of the human body at frequencies between 1 MHz and 10 MHz. A 10.7 MHz frequency modulation (FM) intra-body transmitter and receiver are developed which allow transmission of analog sine waves even in the presence of external noise. Digital data transmission at 9600 bps was also achieved using newly fabricated 10.7 MHz frequency shift keying (FSK) transmitter and receiver devices. The carrier frequency of 10.7 MHz, which is the intermediate frequency in FM radio receivers, means that a wide selection of commercial radio frequency (RF) devices is available.
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paper_title: Simplified circuit modeling and fabrication of intrabody communication devices

paper_content:

Intrabody communication using the human body as the transmission medium enables wireless communication without emitting radio waves into the air. Empirical results on signal transmission gain in the frequency range from 1 to 1000 kHz have shown that the two-electrode model, in which only one of the two electrodes of the transmitter and receiver are attached to the human body, has greater gain than the four-electrode model, in which all four electrodes are attached to the human body. Calculated gains based on four-terminal circuit models of two different electrode arrangements agree with experimental results. The validity of the four-terminal circuit models in the MHz frequency band was investigated using a 10.7-MHz intrabody sine-wave transmitter and receiver fabricated for this purpose. The results also indicate that the two-electrode model is more suitable for high-speed intrabody communication devices than the four-electrode model.
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paper_title: Electric-Field Intrabody Communication Channel Modeling With Finite-Element Method

paper_content:

Electric-field intrabody communication (EF-IBC) is a promising new scheme for the data exchange among wearable biomedical sensors. It uses the body as the signal transmission media. Compared with existing body area network (BAN) schemes, EF-IBC can achieve higher data rate with less transmission power. Until now, the detailed EF-IBC channel mechanism is not well understood. In this work, finite-element method (FEM) is utilized for the first time to investigate the EF-IBC channel. A circuit-coupled FEM model is established for the EF-IBC channel. The FEM model is extensively verified by experimental measurements. The new physical model enables the revelation of characteristics and effects of different components in the EF-IBC channel. The FEM investigation finds that the capacitive return path is critical to the characteristics of the EF-IBC channel. Parameters of the capacitive return path are quantitatively measured. The investigation also finds that the body plays an important role to the return path capacitance. The forward body path can be well modeled by a cascade of π-shaped circuits. Based on the FEM model of the EF-IBC channel, a simplified circuit model is derived to provide an efficient tool for the transceiver design.
---
paper_title: The Human Body Characteristics as a Signal Transmission Medium for Intrabody Communication

paper_content:

The human body characteristics as a signal transmission medium are studied for the application to intrabody communication. The measurements of the body channel cover the frequency range from 100 kHz to 150 MHz and the distance on the body up to 1.2 m. A distributed RC model is developed to analyze the large variation of the channel properties according to the frequency and channel length. The simulation results using the channel model match well with the measurements in both the frequency and time domains. The effect of the ground plane to the body channel transceivers is also investigated and an empirical formula for the minimum ground size is obtained. Finally, the amount of the electromagnetic radiation due to the body antenna effect is measured. With regards to the Federal Communications Commission regulations, the proper frequency range for the intrabody communication is determined to satisfy given bit error rate requirements
---
paper_title: Measurement System for the Characterization of the Human Body as a Communication Channel at Low Frequency

paper_content:

Electronic data transfer by capacitive and galvanic coupling through the human body has been proposed by research and industry as a novel but highly promising technology for ultra low power wireless body LANs. Investigation on the most challenging questions considering data communication becomes enabled with a highly versatile measurement system for frequencies in the range of 10kHz to 1MHz. The human body is characterized as a transmission medium for electrical current by means of measurements and is investigated as communication channel for biomedical parameter monitoring by using different modulation schemes at low frequency. Excellent transmission was achieved on the thorax while the attenuation increases along the extremities. The injected current is 10 times below the maximum allowed contact current and more than 25 times below nerve stimulation. The new technology has shown its feasibility in clinical trials
---
paper_title: Galvanic Coupling Transmission in Intrabody Communication: A Finite Element Approach

paper_content:

Galvanic coupling in intrabody communication (IBC) is a technique that couples low-power and low-frequency voltages and currents into the human body, which acts as a transmission medium, and thus constitutes a promising approach in the design of personal health devices. Despite important advances being made during recent years, the investigation of relevant galvanic IBC parameters, including the influence of human tissues and different electrode configurations, still requires further research efforts. The objective of this work is to disclose knowledge into IBC galvanic coupling transmission mechanisms by using a realistic 3-D finite element model of the human arm. Unlike other computational models for IBC, we have modeled the differential configuration of the galvanic coupling as a four-port network in order to analyze the electric field distribution and current density through different tissues. This has allowed us to provide an insight into signal transmission paths through the human body, showing them to be considerably dependent on variables such as frequency and inter-electrode distance. In addition, other important variables, for example bioimpedance and pathloss, have also been analyzed. Finally, experimental measurements were also carried out for the sake of validation, demonstrating the reliability of the model to emulate in general forms some of the behaviors observed in practice.
---
paper_title: Electric Field Distributions of Wearable Devices Using the Human Body as a Transmission Channel

paper_content:

Recently, wearable devices which use the human body as a transmission channel have been developed. However, there has been a lack of information related to the transmission mechanism of such devices in the physical layer. Electromagnetic communication trials using the human body as a transmission medium have more than a decade's history. However, most of the researches have been conducted by researchers who just want to utilize the fact and practically no physical mechanisms have been researched until recently. Hence, in this paper, the authors propose some calculation models of the human body equipped with the wearable devices by using the finite difference time domain (FDTD) method. Moreover, a biological tissue-equivalent solid phantom is utilized to show the validity of the calculation. From these investigations, the authors determine the transmission mechanism of the wearable devices using the human body as a transmission channel.
---
paper_title: Study of Attenuation and Dispersion Through the Skin in Intrabody Communications Systems

paper_content:

Intrabody communication (IBC) is a technique that uses the human body as a transmission medium for electrical signals to connect wireless body sensors, e.g., in biomedical monitoring systems. In this paper, we propose a simple, but accurate propagation model through the skin based on a distributed-parameter circuit in order to obtain general expressions that could assist in the design of IBC systems. In addition, the model is based on the major electrophysiological properties of the skin. We have found the attenuation and dispersion parameters and they have been successfully compared with several published results, thus showing the tuning capability of the model to different experimental conditions. Finally, we have evaluated different digital modulation schemes in order to assess the tradeoffs between symbol rate, bit error rate, and distance between electrodes of the skin communication channel.
---
paper_title: Distributed Circuit Modeling of Galvanic and Capacitive Coupling for Intrabody Communication

paper_content:

Modeling of intrabody communication (IBC) entails the understanding of the interaction between electromagnetic fields and living tissues. At the same time, an accurate model can provide practical hints toward the deployment of an efficient and secure communication channel for body sensor networks. In the literature, two main IBC coupling techniques have been proposed: galvanic and capacitive coupling. Nevertheless, models that are able to emulate both coupling approaches have not been reported so far. In this paper, a simple model based on a distributed parameter structure with the flexibility to adapt to both galvanic and capacitive coupling has been proposed. In addition, experimental results for both coupling methods were acquired by means of two harmonized measurement setups. The model simulations have been subsequently compared with the experimental data, not only to show their validity but also to revise the practical frequency operation range for both techniques. Finally, the model, along with the experimental results, has also allowed us to provide some practical rules to optimally tackle IBC design.
---
paper_title: Investigation of Galvanic-Coupled Intrabody Communication Using the Human Body Circuit Model

paper_content:

Intrabody Communication (IBC) is a technique that uses the human body as a transmission medium for electrical signals to connect wearable electronic sensors and devices. Understanding the human body as the transmission medium in IBC paves way for practical implementation of IBC in body sensor networks. In this study, we propose a model for galvanic coupling-type IBC based on a simplified equivalent circuit representation of the human upper arm. We propose a new way to calculate the electrode-skin contact impedance. Based on the model and human experimental results, we discuss important characteristics of galvanic coupling-type IBC, namely, the effect of tissues, anthropometry of subjects, and electrode configuration on signal propagation. We found that the dielectric properties of the muscle primarily characterize the received signal when receiver electrodes are located close to transmitter electrodes. When receiver and transmitter electrodes are far apart, the skin dielectric property affects the received signal.
---
paper_title: Electrical properties of tissues and cell suspensions: mechanisms and models

paper_content:

The electrical properties of tissues and cell suspensions are most unusual. They change with frequency in three distinct steps and their dielectric constants reach enormous values at low frequencies. The author concentrates on the "linear" properties observed with applied fields less than about 1 V/cm. The linear properties of interest include the dielectric constant /spl epsiv/ and conductivity /spl sigma/. Extensive measurements have been carried out over a broad frequency range extending from less than 1 Hz to many GHz. A number of mechanism have been identified which explain the observed data. These mechanisms reflect the various compartments of the biological material. These include membranes and their properties, biological macromolecules and fluid compartments inside and outside membranes. The authors summarize the mechanisms which contribute to the total frequency response. >
---
paper_title: Simplified circuit modeling and fabrication of intrabody communication devices

paper_content:

Intrabody communication using the human body as the transmission medium enables wireless communication without emitting radio waves into the air. Empirical results on signal transmission gain in the frequency range from 1 to 1000 kHz have shown that the two-electrode model, in which only one of the two electrodes of the transmitter and receiver are attached to the human body, has greater gain than the four-electrode model, in which all four electrodes are attached to the human body. Calculated gains based on four-terminal circuit models of two different electrode arrangements agree with experimental results. The validity of the four-terminal circuit models in the MHz frequency band was investigated using a 10.7-MHz intrabody sine-wave transmitter and receiver fabricated for this purpose. The results also indicate that the two-electrode model is more suitable for high-speed intrabody communication devices than the four-electrode model.
---
paper_title: Evaluation of the received signal level in relation to the size and carrier frequencies of the wearable device using human body as a transmission channel

paper_content:

Studies of wearable computers have attracted public attention these days. One of the area of interest is the communication system adopted in those wearable computers. As an example, wearable devices which use the human body as a transmission channel have been developed. When a user wearing the transmitter touches the electrode of the receiver, a transmission channel is formed within the human body. In this paper, investigations of the received signal level in relation with the carrier frequency and the size of the transmitter using human body as a transmission channel have been presented. The results show that the received signal voltage is slightly influenced by using higher frequency from 10 MHz to 100 MHz in the ISM frequency bands. However, it strongly depends on the size of the transmitter. In addition, it is necessary that the direction of the electrode of the transmitter is transverse for higher received signal level, compared with the longitudinal direction.
---
paper_title: A study on the receiving signal level in relation with the location of electrodes for wearable devices using human body as a transmission channel

paper_content:

Studies of wearable computers have attracted public attention in these days And one of the area of interest is the communication system adopted in those wearable computers. As an example, wear-able devices which use the human body as a transmission channel, have been developed. This communication system uses near field region of the electromagnetic wave generated by the device which is eventually coupled to human body by electrodes. Hence, the structure of electrodes is one of the key issues for the transmission using human body. However, little is known about the transmission mechanism of such devices in the physical layer. In this paper, we propose calculation models of the transmitter and the receiver attached to the arm using the FDTD method. From this model, we estimated the difference in the received signal level due to the electrode structures of the transmitter and the receiver under various conditions. Moreover, in order to verify the validity of these calculation models, we compared the calculated received signal levels to the measured ones by using the biological tissue-equivalent phantom with die transmitter and the receiver. The result shows a good agreement of the calculated and measured received signal levels. In addition, it is found that the GND electrode of the transmitter strengthens the generated electric field around the ann. However, the existence of a GND electrode for the receiver reduces the received signal level.
---
paper_title: Electric Field Distributions of Wearable Devices Using the Human Body as a Transmission Channel

paper_content:

Recently, wearable devices which use the human body as a transmission channel have been developed. However, there has been a lack of information related to the transmission mechanism of such devices in the physical layer. Electromagnetic communication trials using the human body as a transmission medium have more than a decade's history. However, most of the researches have been conducted by researchers who just want to utilize the fact and practically no physical mechanisms have been researched until recently. Hence, in this paper, the authors propose some calculation models of the human body equipped with the wearable devices by using the finite difference time domain (FDTD) method. Moreover, a biological tissue-equivalent solid phantom is utilized to show the validity of the calculation. From these investigations, the authors determine the transmission mechanism of the wearable devices using the human body as a transmission channel.
---
paper_title: Study of Attenuation and Dispersion Through the Skin in Intrabody Communications Systems

paper_content:

Intrabody communication (IBC) is a technique that uses the human body as a transmission medium for electrical signals to connect wireless body sensors, e.g., in biomedical monitoring systems. In this paper, we propose a simple, but accurate propagation model through the skin based on a distributed-parameter circuit in order to obtain general expressions that could assist in the design of IBC systems. In addition, the model is based on the major electrophysiological properties of the skin. We have found the attenuation and dispersion parameters and they have been successfully compared with several published results, thus showing the tuning capability of the model to different experimental conditions. Finally, we have evaluated different digital modulation schemes in order to assess the tradeoffs between symbol rate, bit error rate, and distance between electrodes of the skin communication channel.
---
paper_title: Distributed Circuit Modeling of Galvanic and Capacitive Coupling for Intrabody Communication

paper_content:

Modeling of intrabody communication (IBC) entails the understanding of the interaction between electromagnetic fields and living tissues. At the same time, an accurate model can provide practical hints toward the deployment of an efficient and secure communication channel for body sensor networks. In the literature, two main IBC coupling techniques have been proposed: galvanic and capacitive coupling. Nevertheless, models that are able to emulate both coupling approaches have not been reported so far. In this paper, a simple model based on a distributed parameter structure with the flexibility to adapt to both galvanic and capacitive coupling has been proposed. In addition, experimental results for both coupling methods were acquired by means of two harmonized measurement setups. The model simulations have been subsequently compared with the experimental data, not only to show their validity but also to revise the practical frequency operation range for both techniques. Finally, the model, along with the experimental results, has also allowed us to provide some practical rules to optimally tackle IBC design.
---
paper_title: Investigation of Galvanic-Coupled Intrabody Communication Using the Human Body Circuit Model

paper_content:

Intrabody Communication (IBC) is a technique that uses the human body as a transmission medium for electrical signals to connect wearable electronic sensors and devices. Understanding the human body as the transmission medium in IBC paves way for practical implementation of IBC in body sensor networks. In this study, we propose a model for galvanic coupling-type IBC based on a simplified equivalent circuit representation of the human upper arm. We propose a new way to calculate the electrode-skin contact impedance. Based on the model and human experimental results, we discuss important characteristics of galvanic coupling-type IBC, namely, the effect of tissues, anthropometry of subjects, and electrode configuration on signal propagation. We found that the dielectric properties of the muscle primarily characterize the received signal when receiver electrodes are located close to transmitter electrodes. When receiver and transmitter electrodes are far apart, the skin dielectric property affects the received signal.
---
paper_title: Electric-Field Intrabody Communication Channel Modeling With Finite-Element Method

paper_content:

Electric-field intrabody communication (EF-IBC) is a promising new scheme for the data exchange among wearable biomedical sensors. It uses the body as the signal transmission media. Compared with existing body area network (BAN) schemes, EF-IBC can achieve higher data rate with less transmission power. Until now, the detailed EF-IBC channel mechanism is not well understood. In this work, finite-element method (FEM) is utilized for the first time to investigate the EF-IBC channel. A circuit-coupled FEM model is established for the EF-IBC channel. The FEM model is extensively verified by experimental measurements. The new physical model enables the revelation of characteristics and effects of different components in the EF-IBC channel. The FEM investigation finds that the capacitive return path is critical to the characteristics of the EF-IBC channel. Parameters of the capacitive return path are quantitatively measured. The investigation also finds that the body plays an important role to the return path capacitance. The forward body path can be well modeled by a cascade of π-shaped circuits. Based on the FEM model of the EF-IBC channel, a simplified circuit model is derived to provide an efficient tool for the transceiver design.
---
paper_title: Galvanic Coupling Transmission in Intrabody Communication: A Finite Element Approach

paper_content:

Galvanic coupling in intrabody communication (IBC) is a technique that couples low-power and low-frequency voltages and currents into the human body, which acts as a transmission medium, and thus constitutes a promising approach in the design of personal health devices. Despite important advances being made during recent years, the investigation of relevant galvanic IBC parameters, including the influence of human tissues and different electrode configurations, still requires further research efforts. The objective of this work is to disclose knowledge into IBC galvanic coupling transmission mechanisms by using a realistic 3-D finite element model of the human arm. Unlike other computational models for IBC, we have modeled the differential configuration of the galvanic coupling as a four-port network in order to analyze the electric field distribution and current density through different tissues. This has allowed us to provide an insight into signal transmission paths through the human body, showing them to be considerably dependent on variables such as frequency and inter-electrode distance. In addition, other important variables, for example bioimpedance and pathloss, have also been analyzed. Finally, experimental measurements were also carried out for the sake of validation, demonstrating the reliability of the model to emulate in general forms some of the behaviors observed in practice.
---
paper_title: The Signal Transmission Mechanism on the Surface of Human Body for Body Channel Communication

paper_content:

The signal transmission mechanism on the surface of the human body is studied for the application to body channel communication (BCC). From Maxwell's equations, the complete equation of electrical field on the human body is developed to obtain a general BCC model. The mechanism of BCC consists of three parts according to the operating frequencies and channel distances: the quasi-static near-field coupling part, the reactive induction-field radiation part, and the surface wave far-field propagation part. The general BCC model by means of the near-field and far-field approximation is developed to be valid in the frequency range from 100 kHz to 100 MHz and distance up to 1.3 m based on the measurements of the body channel characteristics. Finally, path loss characteristics of BCC are formulated for the design of BCC systems and many potential applications.
---
paper_title: Improved transfer function with phase response from quasi-static field modeling for galvanic-type intra-body communication

paper_content:

Transfer function of intra-body communication (IBC) helps the understanding of signal transmission mechanism and hints for efficient communication system design. In this paper, transfer function with phase information based on quasi-static electromagnetic (EM) field modeling for a galvanic-type IBC limb is briefly reviewed. Then the compensation factor, which is calculated by the minimum mean square error (MMSE) method, is introduced to correct the inevitable deviation in actual shapes of human limb and electrical properties of tissues. To verify the effectiveness of correction factor, the square wave response is calculated and experimentally measured. Eventually, our results demonstrate good agreement between theoretical calculation and experimental measurement.
---
paper_title: The Human Body Characteristics as a Signal Transmission Medium for Intrabody Communication

paper_content:

The human body characteristics as a signal transmission medium are studied for the application to intrabody communication. The measurements of the body channel cover the frequency range from 100 kHz to 150 MHz and the distance on the body up to 1.2 m. A distributed RC model is developed to analyze the large variation of the channel properties according to the frequency and channel length. The simulation results using the channel model match well with the measurements in both the frequency and time domains. The effect of the ground plane to the body channel transceivers is also investigated and an empirical formula for the minimum ground size is obtained. Finally, the amount of the electromagnetic radiation due to the body antenna effect is measured. With regards to the Federal Communications Commission regulations, the proper frequency range for the intrabody communication is determined to satisfy given bit error rate requirements
---
paper_title: Study of Channel Characteristics for Galvanic-Type Intra-Body Communication Based on a Transfer Function from a Quasi-Static Field Model

paper_content:

Intra-Body Communication (IBC), which modulates ionic currents over the human body as the communication medium, offers a low power and reliable signal transmission method for information exchange across the body. This paper first briefly reviews the quasi-static electromagnetic (EM) field modeling for a galvanic-type IBC human limb operating below 1 MHz and obtains the corresponding transfer function with correction factor using minimum mean square error (MMSE) technique. Then, the IBC channel characteristics are studied through the comparison between theoretical calculations via this transfer function and experimental measurements in both frequency domain and time domain. High pass characteristics are obtained in the channel gain analysis versus different transmission distances. In addition, harmonic distortions are analyzed in both baseband and passband transmissions for square input waves. The experimental results are consistent with the calculation results from the transfer function with correction factor. Furthermore, we also explore both theoretical and simulation results for the bit-error-rate (BER) performance of several common modulation schemes in the IBC system with a carrier frequency of 500 kHz. It is found that the theoretical results are in good agreement with the simulation results.
---
paper_title: BPSK & QPSK Modulated Data Communication for Biomedical Monitoring Sensor Network

paper_content:

Data communication between body-mounted sen- sors is progressing towards wireless monitoring networks. In this work, digital data communication by galvanic coupling through the body is presented as a promising approach for wireless intra-body communication. The human body itself serves as the transmission medium of electrical current. Both binary and quadrature phase-shift-keying (BPSK and QPSK) modulated data transmissions are implemented and compared for galvanic coupled links between 2 differential electrode pairs. The adaptive system offers up to 1 mA maximum current amplitude between 10 kHz and 1 MHz. Data communication at a rate of up to 64 kbit/s was realized with BER of 10 −4 corresponding to an SNR greater than 6 dB. The novel technology has shown its feasibility in clinical trials. Furthermore, such a low-current approach enables data communication that is more energy-saving than other wireless technologies.
---
paper_title: A Comprehensive Study Into Intrabody Communication Measurements

paper_content:

One of the main objectives of research into intrabody communication (IBC) is the characterization of the human body as a transmission medium for electrical signals. However, such characterization is strongly influenced by the conditions under which the experiments are performed. In addition, the outcomes reported in the literature vary according to the measurement method used, frequently making comparisons among them unfeasible. Further studies are still required in order to establish a methodology for IBC characterization and design. In this paper, both galvanic and capacitive coupling setups have been implemented and a comprehensive set of measurements has been carried out by analyzing fundamental IBC parameters such as optimum frequency range, maximum channel length, and type of electrodes, among others. Consequently, practical conclusions regarding the experimental conditions that optimize IBC performance for each coupling technique have been obtained.
---
paper_title: Initial investigation of channel capacity for galvanic coupling human body communication

paper_content:

Human Body Communication (HBC), which utilizes the human body as communication channel to convey health informatics, is a prospective communication technique for implantable and surface-mounted medical devices. In this article, we have applied Shannon's theorem to derive the channel capacity for the general galvanic coupling HBC channel. The channel characteristics and channel model of general galvanic coupling HBC channel are firstly discussed. Based on this channel model, the channel capacity is derived. By using the water-filling algorithm, the HBC channel capacity is estimated and the suitable frequency bands for low power data transmission in both on-body and in-body HBC channels are found. The results can provide suggestion for better system design.
---
paper_title: A 0.5-V Biomedical System-on-a-Chip for Intrabody Communication System

paper_content:

A low-voltage (0.5 V) and low-power (4.535 mW) monolithic biomedical system-on-a-chip (SOC) consisting of a receiver, a transmitter, a microcontrol unit, and an analog-to-digital converter (ADC), implemented in a 0.18-μm CMOS technology for intrabody communication is first reported. The SOC can take command through a human body and activate (or turn on) the ADC and transmitter inside the SOC. Then, a biomedical signal is converted to digital format and transmitted to the RF gateway through a human body. With this transmission methodology and the proposed SOC circuit, it is much more power efficient than wireless communication. Moreover, since no antenna is required, the chip size of the SOC is only 1.5 mm2, excluding the test pads.
---
paper_title: Intra-body data transmission for the personal area network

paper_content:

Intra-body communication is a wireless means of exchanging information within a personal area network (PAN) between wearable electronic sensors and devices. The feasibility of intra-body communication is confirmed through several experiments on signal propagation within the human body, and a human phantom is designed and used to obtain reproducible results over repeated experiments. Based on the results of these experiments, a prototype transmission system is constructed using aluminum electrodes powered by 3 V DC and operating in the 10.7 MHz frequency modulation (FM) band. This prototype is demonstrated to be capable of transmitting analog signals through the human subjects in the presence of external noise. Digital data transmission at 9600 bps is also achieved using newly fabricated 10.7 MHz frequency shift keying (FSK) transmitter and receiver devices. The carrier frequency of 10.7 MHz is the intermediate frequency of FM radio receivers, meaning that the proposed system can make use of a wide selection of inexpensive, commercial radio frequency devices.
---
paper_title: Distributed Circuit Modeling of Galvanic and Capacitive Coupling for Intrabody Communication

paper_content:

Modeling of intrabody communication (IBC) entails the understanding of the interaction between electromagnetic fields and living tissues. At the same time, an accurate model can provide practical hints toward the deployment of an efficient and secure communication channel for body sensor networks. In the literature, two main IBC coupling techniques have been proposed: galvanic and capacitive coupling. Nevertheless, models that are able to emulate both coupling approaches have not been reported so far. In this paper, a simple model based on a distributed parameter structure with the flexibility to adapt to both galvanic and capacitive coupling has been proposed. In addition, experimental results for both coupling methods were acquired by means of two harmonized measurement setups. The model simulations have been subsequently compared with the experimental data, not only to show their validity but also to revise the practical frequency operation range for both techniques. Finally, the model, along with the experimental results, has also allowed us to provide some practical rules to optimally tackle IBC design.
---
paper_title: Investigation of Galvanic-Coupled Intrabody Communication Using the Human Body Circuit Model

paper_content:

Intrabody Communication (IBC) is a technique that uses the human body as a transmission medium for electrical signals to connect wearable electronic sensors and devices. Understanding the human body as the transmission medium in IBC paves way for practical implementation of IBC in body sensor networks. In this study, we propose a model for galvanic coupling-type IBC based on a simplified equivalent circuit representation of the human upper arm. We propose a new way to calculate the electrode-skin contact impedance. Based on the model and human experimental results, we discuss important characteristics of galvanic coupling-type IBC, namely, the effect of tissues, anthropometry of subjects, and electrode configuration on signal propagation. We found that the dielectric properties of the muscle primarily characterize the received signal when receiver electrodes are located close to transmitter electrodes. When receiver and transmitter electrodes are far apart, the skin dielectric property affects the received signal.
---
paper_title: Experimental Evaluation of Body Channel Response and Digital Modulation Schemes for Intra-body Communications

paper_content:

Intra-body communications is a short range communication solution suitable for Body Area Networks wherein the human body is used as the transmission medium. Currently, some studies have succeeded to transmit and receive simple information. However, intra-body communications could also provide broadband applications such as video streaming which will need high data rates. In this paper, firstly we investigate the propagation characteristics of the human body as a conductor of radio frequency signals. Afterwards, we evaluate five digital modulation schemes for intra-body communications. In the experiments, several distances between transmitter and receiver, symbol rates and frequency carriers are considered to investigate the optimal modulation scheme and the maximum transmission rate achievable. Constellation and eye diagrams and error vector magnitude are the performance parameters measured to evaluate the modulation accuracy.
---
paper_title: Electric-Field Intrabody Communication Channel Modeling With Finite-Element Method

paper_content:

Electric-field intrabody communication (EF-IBC) is a promising new scheme for the data exchange among wearable biomedical sensors. It uses the body as the signal transmission media. Compared with existing body area network (BAN) schemes, EF-IBC can achieve higher data rate with less transmission power. Until now, the detailed EF-IBC channel mechanism is not well understood. In this work, finite-element method (FEM) is utilized for the first time to investigate the EF-IBC channel. A circuit-coupled FEM model is established for the EF-IBC channel. The FEM model is extensively verified by experimental measurements. The new physical model enables the revelation of characteristics and effects of different components in the EF-IBC channel. The FEM investigation finds that the capacitive return path is critical to the characteristics of the EF-IBC channel. Parameters of the capacitive return path are quantitatively measured. The investigation also finds that the body plays an important role to the return path capacitance. The forward body path can be well modeled by a cascade of π-shaped circuits. Based on the FEM model of the EF-IBC channel, a simplified circuit model is derived to provide an efficient tool for the transceiver design.
---
paper_title: BPSK & QPSK Modulated Data Communication for Biomedical Monitoring Sensor Network

paper_content:

Data communication between body-mounted sen- sors is progressing towards wireless monitoring networks. In this work, digital data communication by galvanic coupling through the body is presented as a promising approach for wireless intra-body communication. The human body itself serves as the transmission medium of electrical current. Both binary and quadrature phase-shift-keying (BPSK and QPSK) modulated data transmissions are implemented and compared for galvanic coupled links between 2 differential electrode pairs. The adaptive system offers up to 1 mA maximum current amplitude between 10 kHz and 1 MHz. Data communication at a rate of up to 64 kbit/s was realized with BER of 10 −4 corresponding to an SNR greater than 6 dB. The novel technology has shown its feasibility in clinical trials. Furthermore, such a low-current approach enables data communication that is more energy-saving than other wireless technologies.
---
paper_title: A Comprehensive Study Into Intrabody Communication Measurements

paper_content:

One of the main objectives of research into intrabody communication (IBC) is the characterization of the human body as a transmission medium for electrical signals. However, such characterization is strongly influenced by the conditions under which the experiments are performed. In addition, the outcomes reported in the literature vary according to the measurement method used, frequently making comparisons among them unfeasible. Further studies are still required in order to establish a methodology for IBC characterization and design. In this paper, both galvanic and capacitive coupling setups have been implemented and a comprehensive set of measurements has been carried out by analyzing fundamental IBC parameters such as optimum frequency range, maximum channel length, and type of electrodes, among others. Consequently, practical conclusions regarding the experimental conditions that optimize IBC performance for each coupling technique have been obtained.
---
paper_title: High speed intra-body communication for personal health care

paper_content:

Intra-body communication (IBC) uses the conductive human body as the communication channel for data exchange. As the bio-sensor research is moving towards portable, wearable and implantable designs, IBC has significant potential applications for personal health care. Previous IBC research mainly focused on the electromagnetic (EM) IBC scheme, which resulted in low data rate (kbps). In this paper, we systematically studied the electric field (EF) IBC scheme, which enables 10Mbps data rate. The human body channel is thoroughly measured with attenuation, noise and distortion for the IBC application. High speed EF IBC links are tested with various modulation schemes. The minimum transmission power of different links is measured.
---
paper_title: Effect of body positions and movements in a capacitive intrabody communication channel from 100 kHz to 100 MHz

paper_content:

Intrabody communication (IBC) uses the human body as a signal transmission medium. In this paper we examine the influence of body positions and movements of different test subjects on the capacitive intrabody channel transmission characteristics at 1 MHz, 10 MHz and 40 MHz by comparing the mean value and interquartile range of the gain for different combinations of the influential factors. We showed that up to 10 MHz variations in the gain among different test subjects and the variations caused by different body positions and movements of a test subject are comparable, and lower than the variations at 40 MHz.
---
paper_title: Electric Field Distributions of Wearable Devices Using the Human Body as a Transmission Channel

paper_content:

Recently, wearable devices which use the human body as a transmission channel have been developed. However, there has been a lack of information related to the transmission mechanism of such devices in the physical layer. Electromagnetic communication trials using the human body as a transmission medium have more than a decade's history. However, most of the researches have been conducted by researchers who just want to utilize the fact and practically no physical mechanisms have been researched until recently. Hence, in this paper, the authors propose some calculation models of the human body equipped with the wearable devices by using the finite difference time domain (FDTD) method. Moreover, a biological tissue-equivalent solid phantom is utilized to show the validity of the calculation. From these investigations, the authors determine the transmission mechanism of the wearable devices using the human body as a transmission channel.
---
paper_title: A 0.5-V Biomedical System-on-a-Chip for Intrabody Communication System

paper_content:

A low-voltage (0.5 V) and low-power (4.535 mW) monolithic biomedical system-on-a-chip (SOC) consisting of a receiver, a transmitter, a microcontrol unit, and an analog-to-digital converter (ADC), implemented in a 0.18-μm CMOS technology for intrabody communication is first reported. The SOC can take command through a human body and activate (or turn on) the ADC and transmitter inside the SOC. Then, a biomedical signal is converted to digital format and transmitted to the RF gateway through a human body. With this transmission methodology and the proposed SOC circuit, it is much more power efficient than wireless communication. Moreover, since no antenna is required, the chip size of the SOC is only 1.5 mm2, excluding the test pads.
---
paper_title: Intra-body data transmission for the personal area network

paper_content:

Intra-body communication is a wireless means of exchanging information within a personal area network (PAN) between wearable electronic sensors and devices. The feasibility of intra-body communication is confirmed through several experiments on signal propagation within the human body, and a human phantom is designed and used to obtain reproducible results over repeated experiments. Based on the results of these experiments, a prototype transmission system is constructed using aluminum electrodes powered by 3 V DC and operating in the 10.7 MHz frequency modulation (FM) band. This prototype is demonstrated to be capable of transmitting analog signals through the human subjects in the presence of external noise. Digital data transmission at 9600 bps is also achieved using newly fabricated 10.7 MHz frequency shift keying (FSK) transmitter and receiver devices. The carrier frequency of 10.7 MHz is the intermediate frequency of FM radio receivers, meaning that the proposed system can make use of a wide selection of inexpensive, commercial radio frequency devices.
---
paper_title: Distributed Circuit Modeling of Galvanic and Capacitive Coupling for Intrabody Communication

paper_content:

Modeling of intrabody communication (IBC) entails the understanding of the interaction between electromagnetic fields and living tissues. At the same time, an accurate model can provide practical hints toward the deployment of an efficient and secure communication channel for body sensor networks. In the literature, two main IBC coupling techniques have been proposed: galvanic and capacitive coupling. Nevertheless, models that are able to emulate both coupling approaches have not been reported so far. In this paper, a simple model based on a distributed parameter structure with the flexibility to adapt to both galvanic and capacitive coupling has been proposed. In addition, experimental results for both coupling methods were acquired by means of two harmonized measurement setups. The model simulations have been subsequently compared with the experimental data, not only to show their validity but also to revise the practical frequency operation range for both techniques. Finally, the model, along with the experimental results, has also allowed us to provide some practical rules to optimally tackle IBC design.
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paper_title: A low-frequency low-noise transceiver for human body channel communication

paper_content:

This paper presents a low power, highly integrated wireless transceiver ASIC designated for peer-to-peer wearable and portable data communication apparatus. The transceiver utilized a novel implementation of energy-efficient wideband impulse communication that uses the human body as the transmission medium, provides high communication data rate, low power consumption, high reception sensitivity and wide operation frequencies. The transceiver frequency was measured to be in the range of 0.3–15MHz. The data rate was approximately 5Mbps at a total power consumption of 5mW. The ASIC was fabricated with a standard 0.18-μιη CMOS process.
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paper_title: 79pJ/b 80Mb/s full-duplex transceiver and 42.5jiW 100kb/s super-regenerative transceiver for body channel communication

paper_content:

A low-energy 40MHz / 160MHz dual band full duplex body channel communication (BCC) transceiver and 13.56MHz R-C oscillator-based super-regenerative receiver are integrated in 65nm mixed mode CMOS process for both highspeed (HS) and low-speed (LS) biomedical applications. The body channel bandwidth is extended up to 200MHz, enabling energy efficient and wide bandwidth communication. The on-chip R-C duplexer uses notch filters for full duplex communication with 40Mb/s data rate and combined dual band operation shows 80Mb/s data-rate with half duplex communication. The R-C oscillator-based super-regenerative receiver achieves >60dB interference rejection (Q-factor over 1000) with 100kb/s data rate and 42.5μW power consumption under 0.8V supply.
---
paper_title: A very low-power consumption wireless ECG monitoring system using body as a signal transmission medium

paper_content:

A very low-power consumption wireless system for monitoring ECG (electrocardiogram) is proposed. It consists of an ECG detector/transmitter located on the chest and the relay transmitter placed at the wrist. Between the detector part and the relay transmitter, the signal is send as the AC micro current flows through the tissue of the body. Since this method achieves very low-power signal transmission of about 8 /spl mu/W (400 mV/sub RMS//spl times/20 /spl mu/A/sub RMS/), the system can be driven by a very small power source like a thin film battery. A similar wireless transmission method can be applied for other medical signal/data sensing micro systems sharing the same relay transmitter.
---
paper_title: Intrabody buses for data and power

paper_content:

While wearable computers are empowering fashion accessories, they bring with them a tangle of wires which connect their parts. As these subsystems begin to decouple and operate on less power, it becomes possible to wirelessly distribute their required data and power using to the wearer's body. We have demonstrated systems that transmit and receive both data and power, and are working to combine the two.
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paper_title: Experimental Evaluation of Body Channel Response and Digital Modulation Schemes for Intra-body Communications

paper_content:

Intra-body communications is a short range communication solution suitable for Body Area Networks wherein the human body is used as the transmission medium. Currently, some studies have succeeded to transmit and receive simple information. However, intra-body communications could also provide broadband applications such as video streaming which will need high data rates. In this paper, firstly we investigate the propagation characteristics of the human body as a conductor of radio frequency signals. Afterwards, we evaluate five digital modulation schemes for intra-body communications. In the experiments, several distances between transmitter and receiver, symbol rates and frequency carriers are considered to investigate the optimal modulation scheme and the maximum transmission rate achievable. Constellation and eye diagrams and error vector magnitude are the performance parameters measured to evaluate the modulation accuracy.
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paper_title: Bit error rate estimation for galvanic-type intra-body communication using experimental eye-diagram and jitter characteristics

paper_content:

Bit error rate (BER), which indicates the reliability of communicate channel, is one of the most important values in all kinds of communication system, including intra-body communication (IBC). In order to know more about IBC channel, this paper presents a new method of BER estimation for galvanic-type IBC using experimental eye-diagram and jitter characteristics. To lay the foundation for our methodology, the fundamental relationships between eye-diagram, jitter and BER are first reviewed. Then experiments based on human lower arm IBC are carried out using quadrature phase shift keying (QPSK) modulation scheme and 500 KHz carries frequency. In our IBC experiments, the symbol rate is from 10 Ksps to 100 Ksps, with two transmitted power settings, 0 dBm and -5 dBm. Finally, the BER results were obtained after calculation by experimental data through the relationships among eye-diagram, jitter and BER. These results are then compared with theoretical values and they show good agreement, especially when SNR is between 6 dB to 11 dB. Additionally, these results demonstrate assuming the noise of galvanic-type IBC channel as Additive White Gaussian Noise (AWGN) in previous study is applicable.
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paper_title: A 60 kb/s–10 Mb/s Adaptive Frequency Hopping Transceiver for Interference-Resilient Body Channel Communication

paper_content:

An interference-resilient 60 kb/s-10 Mb/s body channel transceiver using the human body as a signal transmission medium is designed for multimedia and medical data transaction in body-area network. The body antenna effect which interferes with signals in the human body channel is examined. The body-induced interferences degrade the SIR of the signal to -22 dB in the worst case. In order to overcome the body antenna effect, a 4-channel adaptive frequency hopping scheme using the 30-120 MHz band is introduced to the body channel transceiver. A direct-switching modulator using dual frequency synthesizers and a DLL-based demodulator are proposed for 10 Mb/s FSK and the 4.2 mus hopping time. The transceiver fabricated with 0.18 mum CMOS withstands -28 dB SIR and its operating distance is over 1.8 m with - 25 dB SIR. Its energy consumption is 0.37 nJ/b with -65 dBm sensitivity.
---
paper_title: Study of Channel Characteristics for Galvanic-Type Intra-Body Communication Based on a Transfer Function from a Quasi-Static Field Model

paper_content:

Intra-Body Communication (IBC), which modulates ionic currents over the human body as the communication medium, offers a low power and reliable signal transmission method for information exchange across the body. This paper first briefly reviews the quasi-static electromagnetic (EM) field modeling for a galvanic-type IBC human limb operating below 1 MHz and obtains the corresponding transfer function with correction factor using minimum mean square error (MMSE) technique. Then, the IBC channel characteristics are studied through the comparison between theoretical calculations via this transfer function and experimental measurements in both frequency domain and time domain. High pass characteristics are obtained in the channel gain analysis versus different transmission distances. In addition, harmonic distortions are analyzed in both baseband and passband transmissions for square input waves. The experimental results are consistent with the calculation results from the transfer function with correction factor. Furthermore, we also explore both theoretical and simulation results for the bit-error-rate (BER) performance of several common modulation schemes in the IBC system with a carrier frequency of 500 kHz. It is found that the theoretical results are in good agreement with the simulation results.
---
paper_title: Statistical Modeling of Intra-body Propagation Channel

paper_content:

Intra-body communications based on near-field radio signals is a short range communication solution suitable for body area networks wherein the human body is used as the transmission medium. This paper proposes a statistical model for the intra-body propagation channel based on experimental data of the human body transmission characteristics. The channel models are presented over three measurements configurations with several transmitter and receiver locations and considering two common scenarios: the human body not moving and walking. We define the statistical models in terms of most fitting probability density function to the experimental data of the received signal power among 15 families of probability distributions. These general models should be useful for simulating propagation effects in the laboratory and, therefore, we believe that these models will play a significant role in the design and evaluation of intra-body communication systems.
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paper_title: BPSK & QPSK Modulated Data Communication for Biomedical Monitoring Sensor Network

paper_content:

Data communication between body-mounted sen- sors is progressing towards wireless monitoring networks. In this work, digital data communication by galvanic coupling through the body is presented as a promising approach for wireless intra-body communication. The human body itself serves as the transmission medium of electrical current. Both binary and quadrature phase-shift-keying (BPSK and QPSK) modulated data transmissions are implemented and compared for galvanic coupled links between 2 differential electrode pairs. The adaptive system offers up to 1 mA maximum current amplitude between 10 kHz and 1 MHz. Data communication at a rate of up to 64 kbit/s was realized with BER of 10 −4 corresponding to an SNR greater than 6 dB. The novel technology has shown its feasibility in clinical trials. Furthermore, such a low-current approach enables data communication that is more energy-saving than other wireless technologies.
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paper_title: Measurement System for the Characterization of the Human Body as a Communication Channel at Low Frequency

paper_content:

Electronic data transfer by capacitive and galvanic coupling through the human body has been proposed by research and industry as a novel but highly promising technology for ultra low power wireless body LANs. Investigation on the most challenging questions considering data communication becomes enabled with a highly versatile measurement system for frequencies in the range of 10kHz to 1MHz. The human body is characterized as a transmission medium for electrical current by means of measurements and is investigated as communication channel for biomedical parameter monitoring by using different modulation schemes at low frequency. Excellent transmission was achieved on the thorax while the attenuation increases along the extremities. The injected current is 10 times below the maximum allowed contact current and more than 25 times below nerve stimulation. The new technology has shown its feasibility in clinical trials
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paper_title: Wearable key: device for personalizing nearby environment

paper_content:

This paper describes a system that allows users who obtain a "wearable ID key" to personalize dynamically ubiquitous computers by simply touching them. We call the concept of providing personalized service by touch "Active Personalization". For active personalization, users only have to wear a digital key and do not have to carry around other computers. When users touch ubiquitous computers with their wearable key, the keyholes of the ubiquitous computers recognize their IDs and can personalize the computers. We developed a new network technology between keys and keyholes that enables digital information to be carried through a person's body based on a near-field technology we call TouchNet.
---
paper_title: A Comprehensive Study Into Intrabody Communication Measurements

paper_content:

One of the main objectives of research into intrabody communication (IBC) is the characterization of the human body as a transmission medium for electrical signals. However, such characterization is strongly influenced by the conditions under which the experiments are performed. In addition, the outcomes reported in the literature vary according to the measurement method used, frequently making comparisons among them unfeasible. Further studies are still required in order to establish a methodology for IBC characterization and design. In this paper, both galvanic and capacitive coupling setups have been implemented and a comprehensive set of measurements has been carried out by analyzing fundamental IBC parameters such as optimum frequency range, maximum channel length, and type of electrodes, among others. Consequently, practical conclusions regarding the experimental conditions that optimize IBC performance for each coupling technique have been obtained.
---
paper_title: A 2Mb/s Wideband Pulse Transceiver with Direct-Coupled Interface for Human Body Communications

paper_content:

A battery-powered wideband pulse transceiver with a direct-coupled interface is presented for human-body communications. The optimum channel bandwidth of 10kHz to 100MHz is identified as the bodywire channel. The transceiver based on all-digital CDR circuit with quadratic sampling technique has 2Mb/s data rate at a BER of 10-7. The 0.25mum CMOS transceiver occupies 0.85mm2 and consumes less than 0.2mW from a 1V supply
---
paper_title: High speed intra-body communication for personal health care

paper_content:

Intra-body communication (IBC) uses the conductive human body as the communication channel for data exchange. As the bio-sensor research is moving towards portable, wearable and implantable designs, IBC has significant potential applications for personal health care. Previous IBC research mainly focused on the electromagnetic (EM) IBC scheme, which resulted in low data rate (kbps). In this paper, we systematically studied the electric field (EF) IBC scheme, which enables 10Mbps data rate. The human body channel is thoroughly measured with attenuation, noise and distortion for the IBC application. High speed EF IBC links are tested with various modulation schemes. The minimum transmission power of different links is measured.
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paper_title: A near-field-sensing transceiver for intrabody communication based on the electrooptic effect

paper_content:

This paper describes a near-field-sensing transceiver for intrabody communication, in which the human body is the transmission medium. The key component of the transceiver is an electric-field sensor implemented with an electrooptic crystal and laser light. This sensor is suitable for detection of the small and unstable electric fields produced by the human body because it has extremely high input impedance. This transceiver enables IEEE 802.3 half-duplex communication of 10 Mb/s through a person's body in an operating range of about 150 cm between the hands. The packet error rate of 0.04% is obtained at packet size of 1070 octet. This paper explains the configuration and performance of the transceiver and presents results of a communication test.
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paper_title: Empirical measurements of intrabody communication performance under varied physical configurations

paper_content:

Intrabody communication (IBC) is a wireless communications technology that uses a person's body as the transmission medium for imperceptible electrical signals. Because communication is limited to the vicinity of a person's body, ambiguities arising from communication between personal devices and environmental devices when multiple people are present can, in theory, be solved simply. Intrabody communication also potentially allows data to be transferred when a person touches an IBC-enabled device. We have designed and constructed an intrabody communication system, modeled after Zimmerman's original design, and extended it to operate up to 38.4Kbps and to calculate signal strength. In this paper, we present quantitative measurements of data error rates and signal strength while varying hand distance to transceiver plate, electrode location on the body, touch plate size and shape, and several other factors. We find that plate size and shape have only minor effects, but that the distance to plate and the coupling mechanism significantly effect signal strength. We also find that portable devices, with poor ground coupling, suffer more significant signal attenuation. Our goal is to promote design guidelines for this technology and identify the best contexts for its effective deployment.
---
paper_title: Transceiver for Human Body Communication Using Frequency Selective Digital Transmission

paper_content:

This paper presents a transceiver module for human body communications whereby a spread signal with a group of 64 Walsh codes is directly transferred through a human body at a chip rate of 32 Mcps. Frequency selective digital transmission moves the signal spectrum over 5 MHz without continuous frequency modulation and increases the immunity to induced interference by the processing gain. A simple receiver structure with no additional analog circuitry for the transmitter has been developed and has a sensitivity of 250 . The high sensitivity of the receiver makes it possible to communicate between mobile devices using a human body as the transmission medium. It enables half-duplex communication of 2 Mbps within an operating range of up to 170 cm between the ultra-mobile PCs held between fingertips of each hand with a packet error rate of lower than . The transceiver module consumes 59 mA with a 3.3 V power supply.
---
paper_title: A 5.2 mW IEEE 802.15.6 HBC Standard Compatible Transceiver With Power Efficient Delay-Locked-Loop Based BPSK Demodulator

paper_content:

A Low-power IEEE 802.15.6 human body communication (HBC) fully compatible transceiver is implemented in 130 nm CMOS process. In this work, the proposed HBC transceiver satisfying all the standard requirements has four key features for low power consumption which includes: 1) low-power analog active filters for TX spectral mask: 30% power reduction; 2) delayed locked loop (DLL) based BPSK receiver with the S/H operation for turning off unnecessary blocks: 40% power reduction; 3) low-power mode (LP-mode) receiver with the received signal strength indicator (RSSI) output data: 50% power reduction; and 4) reconfigurable LNA with RSSI output data: 60% power reduction. As a result, the proposed transceiver can fully satisfy the HBC standard requirements while consuming 5.2 mW from the 1.2 V supply.
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paper_title: Propagation characteristics of intra-body communications for body area networks

paper_content:

Body area networks (BAN) will become increasingly important in the future personal communication systems. We believe that intra-body communications (IBC) based on near field electromagnetic waves is a suitable solution for BAN. This paper presents experimental measurements of the frequency and time domain responses in order to investigate the transmission characteristics of the human body as a conductor of low power high frequency radio signals (up to 3GHz). In the measurements, several distances between transmitter and receiver (up to a long distance from the head to the foot) and six test people (to study the possible variation results due to physiological body effects) have been considered. Besides analyzing the intra-body channel response, we also aim to define a suitable frequency range for IBC. Finally, this paper also presents an initial evaluation study of several digital modulation schemes in order to investigate the optimal technique for IBC.
---
paper_title: A 0.5-V Biomedical System-on-a-Chip for Intrabody Communication System

paper_content:

A low-voltage (0.5 V) and low-power (4.535 mW) monolithic biomedical system-on-a-chip (SOC) consisting of a receiver, a transmitter, a microcontrol unit, and an analog-to-digital converter (ADC), implemented in a 0.18-μm CMOS technology for intrabody communication is first reported. The SOC can take command through a human body and activate (or turn on) the ADC and transmitter inside the SOC. Then, a biomedical signal is converted to digital format and transmitted to the RF gateway through a human body. With this transmission methodology and the proposed SOC circuit, it is much more power efficient than wireless communication. Moreover, since no antenna is required, the chip size of the SOC is only 1.5 mm2, excluding the test pads.
---
paper_title: Intra-body data transmission for the personal area network

paper_content:

Intra-body communication is a wireless means of exchanging information within a personal area network (PAN) between wearable electronic sensors and devices. The feasibility of intra-body communication is confirmed through several experiments on signal propagation within the human body, and a human phantom is designed and used to obtain reproducible results over repeated experiments. Based on the results of these experiments, a prototype transmission system is constructed using aluminum electrodes powered by 3 V DC and operating in the 10.7 MHz frequency modulation (FM) band. This prototype is demonstrated to be capable of transmitting analog signals through the human subjects in the presence of external noise. Digital data transmission at 9600 bps is also achieved using newly fabricated 10.7 MHz frequency shift keying (FSK) transmitter and receiver devices. The carrier frequency of 10.7 MHz is the intermediate frequency of FM radio receivers, meaning that the proposed system can make use of a wide selection of inexpensive, commercial radio frequency devices.
---
paper_title: Development and performance analysis of an intra-body communication device

paper_content:

Personal area networks would benefit from a wireless communication system in which a variety of information could be exchanged through wearable electronic devices and sensors. Intra-body communication using the human body as the transmission medium enables wireless communication without transmitting radio waves through the air. A human arm phantom is designed and used to reduce uncertainty in experiments with the human body. The phantom exhibits transmission characteristics similar to those of the human body at frequencies between 1 MHz and 10 MHz. A 10.7 MHz frequency modulation (FM) intra-body transmitter and receiver are developed which allow transmission of analog sine waves even in the presence of external noise. Digital data transmission at 9600 bps was also achieved using newly fabricated 10.7 MHz frequency shift keying (FSK) transmitter and receiver devices. The carrier frequency of 10.7 MHz, which is the intermediate frequency in FM radio receivers, means that a wide selection of commercial radio frequency (RF) devices is available.
---
paper_title: Investigation of Galvanic-Coupled Intrabody Communication Using the Human Body Circuit Model

paper_content:

Intrabody Communication (IBC) is a technique that uses the human body as a transmission medium for electrical signals to connect wearable electronic sensors and devices. Understanding the human body as the transmission medium in IBC paves way for practical implementation of IBC in body sensor networks. In this study, we propose a model for galvanic coupling-type IBC based on a simplified equivalent circuit representation of the human upper arm. We propose a new way to calculate the electrode-skin contact impedance. Based on the model and human experimental results, we discuss important characteristics of galvanic coupling-type IBC, namely, the effect of tissues, anthropometry of subjects, and electrode configuration on signal propagation. We found that the dielectric properties of the muscle primarily characterize the received signal when receiver electrodes are located close to transmitter electrodes. When receiver and transmitter electrodes are far apart, the skin dielectric property affects the received signal.
---
paper_title: A very low-power consumption wireless ECG monitoring system using body as a signal transmission medium

paper_content:

A very low-power consumption wireless system for monitoring ECG (electrocardiogram) is proposed. It consists of an ECG detector/transmitter located on the chest and the relay transmitter placed at the wrist. Between the detector part and the relay transmitter, the signal is send as the AC micro current flows through the tissue of the body. Since this method achieves very low-power signal transmission of about 8 /spl mu/W (400 mV/sub RMS//spl times/20 /spl mu/A/sub RMS/), the system can be driven by a very small power source like a thin film battery. A similar wireless transmission method can be applied for other medical signal/data sensing micro systems sharing the same relay transmitter.
---
paper_title: A Galvanic Coupling Method for Assessing Hydration Rates

paper_content:

Recent advances in biomedical sensors, data acquisition techniques, microelectronics and wireless communication systems opened up the use of wearable technology for ehealth monitoring. We introduce a galvanic coupled intrabody communication for monitoring human body hydration. Studies in hydration provide the information necessary for understanding the desired fluid levels for optimal performance of the body’s physiological and metabolic processes during exercise and activities of daily living. Current measurement techniques are mostly suitable for laboratory purposes due to their complexity and technical requirements. Less technical methods such as urine color observation and skin turgor testing are subjective and cannot be integrated into a wearable device. Bioelectrical impedance methods are popular but mostly used for estimating total body water with limited accuracy and sensitive to 800 mL–1000 mL change in body fluid levels. We introduce a non-intrusive and simple method of tracking hydration rates that can detect up to 1.30 dB reduction in attenuation when as little as 100 mL of water is consumed. Our results show that galvanic coupled intrabody signal propagation can provide qualitative hydration and dehydration rates in line with changes in an individual’s urine specific gravity and body mass. The real-time changes in galvanic coupled intrabody signal attenuation can be integrated into wearable electronic devices to evaluate body fluid levels on a particular area of interest and can aid diagnosis and treatment of fluid disorders such as lymphoedema.
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paper_title: Direct Measurement of Elbow Joint Angle Using Galvanic Couple System

paper_content:

This paper proposes a simple approach to measure the elbow joint angle (EJA) using galvanic coupling system (GCS), directly; whereas, the traditional methods involved in either complex machine-learning task or arm movement models in which the consideration of model parameters are not accurate very often. First, a correlation between the EJA and GCS data has been established by defining a polynomial function based on a simple six-impedance model of human upper arm, where the EJA ( $\theta$ ) has been achieved by moving the forearm along the sagittal and transverse planes with different loads (empty hand, 1 and 2 kg). The coefficients of the polynomial are estimated based on the polynomial fit technique in which the actual angles (reference frame) are calculated by using motion data. In total, eleven subjects (seven males and four females) with the age of 30 ± 6 years have been considered during the experiment. However, the GCS data of eight subjects are used to derive the correlation, exclusively. Furthermore, the influence of muscle fatigue and different loads on the derived correlation has been studied. Next, based on the derived correlation, the EJA has been measured in two parts—inside and outside tests by considering six subjects. The results show that the proposed idea can measure the EJA very effectively with error up to ±0.11 rad (6°). Moreover, in a performance comparison, the proposed approach shows its compatibility by indicating low complexity, higher accuracy, and easy to measure.
---
paper_title: A 0.5-V Biomedical System-on-a-Chip for Intrabody Communication System

paper_content:

A low-voltage (0.5 V) and low-power (4.535 mW) monolithic biomedical system-on-a-chip (SOC) consisting of a receiver, a transmitter, a microcontrol unit, and an analog-to-digital converter (ADC), implemented in a 0.18-μm CMOS technology for intrabody communication is first reported. The SOC can take command through a human body and activate (or turn on) the ADC and transmitter inside the SOC. Then, a biomedical signal is converted to digital format and transmitted to the RF gateway through a human body. With this transmission methodology and the proposed SOC circuit, it is much more power efficient than wireless communication. Moreover, since no antenna is required, the chip size of the SOC is only 1.5 mm2, excluding the test pads.
---
paper_title: Development and performance analysis of an intra-body communication device

paper_content:

Personal area networks would benefit from a wireless communication system in which a variety of information could be exchanged through wearable electronic devices and sensors. Intra-body communication using the human body as the transmission medium enables wireless communication without transmitting radio waves through the air. A human arm phantom is designed and used to reduce uncertainty in experiments with the human body. The phantom exhibits transmission characteristics similar to those of the human body at frequencies between 1 MHz and 10 MHz. A 10.7 MHz frequency modulation (FM) intra-body transmitter and receiver are developed which allow transmission of analog sine waves even in the presence of external noise. Digital data transmission at 9600 bps was also achieved using newly fabricated 10.7 MHz frequency shift keying (FSK) transmitter and receiver devices. The carrier frequency of 10.7 MHz, which is the intermediate frequency in FM radio receivers, means that a wide selection of commercial radio frequency (RF) devices is available.
---
paper_title: Electrical stimulation of excitable tissue: design of efficacious and safe protocols

paper_content:

The physical basis for electrical stimulation of excitable tissue, as used by electrophysiological researchers and clinicians in functional electrical stimulation, is presented with emphasis on the fundamental mechanisms of charge injection at the electrode/tissue interface. Faradaic and non-Faradaic charge transfer mechanisms are presented and contrasted. An electrical model of the electrode/tissue interface is given. The physical basis for the origin of electrode potentials is given. Various methods of controlling charge delivery during pulsing are presented. Electrochemical reversibility is discussed. Commonly used electrode materials and stimulation protocols are reviewed in terms of stimulation efficacy and safety. Principles of stimulation of excitable tissue are reviewed with emphasis on efficacy and safety. Mechanisms of damage to tissue and the electrode are reviewed. © 2004 Elsevier B.V. All rights reserved.
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paper_title: Simplified circuit modeling and fabrication of intrabody communication devices

paper_content:

Intrabody communication using the human body as the transmission medium enables wireless communication without emitting radio waves into the air. Empirical results on signal transmission gain in the frequency range from 1 to 1000 kHz have shown that the two-electrode model, in which only one of the two electrodes of the transmitter and receiver are attached to the human body, has greater gain than the four-electrode model, in which all four electrodes are attached to the human body. Calculated gains based on four-terminal circuit models of two different electrode arrangements agree with experimental results. The validity of the four-terminal circuit models in the MHz frequency band was investigated using a 10.7-MHz intrabody sine-wave transmitter and receiver fabricated for this purpose. The results also indicate that the two-electrode model is more suitable for high-speed intrabody communication devices than the four-electrode model.
---
paper_title: Study of Channel Characteristics for Galvanic-Type Intra-Body Communication Based on a Transfer Function from a Quasi-Static Field Model

paper_content:

Intra-Body Communication (IBC), which modulates ionic currents over the human body as the communication medium, offers a low power and reliable signal transmission method for information exchange across the body. This paper first briefly reviews the quasi-static electromagnetic (EM) field modeling for a galvanic-type IBC human limb operating below 1 MHz and obtains the corresponding transfer function with correction factor using minimum mean square error (MMSE) technique. Then, the IBC channel characteristics are studied through the comparison between theoretical calculations via this transfer function and experimental measurements in both frequency domain and time domain. High pass characteristics are obtained in the channel gain analysis versus different transmission distances. In addition, harmonic distortions are analyzed in both baseband and passband transmissions for square input waves. The experimental results are consistent with the calculation results from the transfer function with correction factor. Furthermore, we also explore both theoretical and simulation results for the bit-error-rate (BER) performance of several common modulation schemes in the IBC system with a carrier frequency of 500 kHz. It is found that the theoretical results are in good agreement with the simulation results.
---
paper_title: Signal Transmission by Galvanic Coupling Through the Human Body

paper_content:

Galvanic coupling is a promising approach for wireless intrabody data transmission between sensors. Using the human body as a transmission medium for electrical signals becomes a novel data communication technique in biomedical monitoring systems. In this paper, special attention is given to the coupling of the current into the human body. Safety requirements have to be fulfilled, and optimal signal coupling is of essence. Therefore, different electrodes are compared. A test system offers up to 1 mA contact current modulated in the frequency range of 10 kHz to 1 MHz. The injected current is up to 20 times below the maximum allowed contact current. Such a low-current approach enables data communication that is more energy saving than other wireless technologies.
---
paper_title: A Comprehensive Study Into Intrabody Communication Measurements

paper_content:

One of the main objectives of research into intrabody communication (IBC) is the characterization of the human body as a transmission medium for electrical signals. However, such characterization is strongly influenced by the conditions under which the experiments are performed. In addition, the outcomes reported in the literature vary according to the measurement method used, frequently making comparisons among them unfeasible. Further studies are still required in order to establish a methodology for IBC characterization and design. In this paper, both galvanic and capacitive coupling setups have been implemented and a comprehensive set of measurements has been carried out by analyzing fundamental IBC parameters such as optimum frequency range, maximum channel length, and type of electrodes, among others. Consequently, practical conclusions regarding the experimental conditions that optimize IBC performance for each coupling technique have been obtained.
---
paper_title: A new technique for transmission of signals from implantable transducers

paper_content:

To reduce space requirements for implant electronics in in vivo telemetry applications, the purpose of this project was to develop and test a new data transmission method that utilizes the ionic properties of bodily fluids as the transmission medium. Motivated by an interest in using the new method to transmit information from a sensor which measures tension in anterior cruciate ligament (ACL) grafts, a sine wave was injected into a cadaver leg using platinum electrodes implanted into the lateral femoral epicondyle. The signal was detected by electromyogram (EMG) surface electrodes. The effect of transmission frequency, the current injected, interelectrode separation, distance of the electrodes from the joint line, and the surface of electrode placement on the signal attenuation was studied. The logarithmic relation between attenuation and frequency was constant from 2 kHz until 10 kHz. For frequencies above 10 kHz, the attenuation increased linearly at the rate of 1 dB/octave. Attenuation was inversely sensitive to both current and interelectrode separation with larger separations and currents giving less attenuation. Attenuation was significantly less for the lateral thigh surface than for the anterior surface and increased with increasing distance from the joint line for both surfaces. For the application of interest here, suitable values of transmission variables to avoid the possible negative consequences of injecting current into living tissue are a current of 3 mA injected at a frequency of 37 kHz. The values of reception variables for minimum attenuation are wide interelectrode separation (5 cm) with the electrodes placed 5 cm proximal of the joint line on the lateral surface of the thigh. With the exception of the surface which is application dependent, these values of the reception variables should also be appropriate for other applications.
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paper_title: A 0.5-V Biomedical System-on-a-Chip for Intrabody Communication System

paper_content:

A low-voltage (0.5 V) and low-power (4.535 mW) monolithic biomedical system-on-a-chip (SOC) consisting of a receiver, a transmitter, a microcontrol unit, and an analog-to-digital converter (ADC), implemented in a 0.18-μm CMOS technology for intrabody communication is first reported. The SOC can take command through a human body and activate (or turn on) the ADC and transmitter inside the SOC. Then, a biomedical signal is converted to digital format and transmitted to the RF gateway through a human body. With this transmission methodology and the proposed SOC circuit, it is much more power efficient than wireless communication. Moreover, since no antenna is required, the chip size of the SOC is only 1.5 mm2, excluding the test pads.
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paper_title: A Comprehensive Study Into Intrabody Communication Measurements

paper_content:

One of the main objectives of research into intrabody communication (IBC) is the characterization of the human body as a transmission medium for electrical signals. However, such characterization is strongly influenced by the conditions under which the experiments are performed. In addition, the outcomes reported in the literature vary according to the measurement method used, frequently making comparisons among them unfeasible. Further studies are still required in order to establish a methodology for IBC characterization and design. In this paper, both galvanic and capacitive coupling setups have been implemented and a comprehensive set of measurements has been carried out by analyzing fundamental IBC parameters such as optimum frequency range, maximum channel length, and type of electrodes, among others. Consequently, practical conclusions regarding the experimental conditions that optimize IBC performance for each coupling technique have been obtained.
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paper_title: High speed intra-body communication for personal health care

paper_content:

Intra-body communication (IBC) uses the conductive human body as the communication channel for data exchange. As the bio-sensor research is moving towards portable, wearable and implantable designs, IBC has significant potential applications for personal health care. Previous IBC research mainly focused on the electromagnetic (EM) IBC scheme, which resulted in low data rate (kbps). In this paper, we systematically studied the electric field (EF) IBC scheme, which enables 10Mbps data rate. The human body channel is thoroughly measured with attenuation, noise and distortion for the IBC application. High speed EF IBC links are tested with various modulation schemes. The minimum transmission power of different links is measured.
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paper_title: Balun's effect on the measurement of transmission characteristics for intrabody communication channel

paper_content:

Intrabody communication (IBC) is a promising technology that enables the improvement of digital healthcare devices. IBC uses the human body as a transmission media, and the accurate transmission model is important for the design of transceivers. In the measurements of transmission characteristics, baluns have been widely used to separate the grounds of transmitter and receiver. In this work, we analyze the balun's effect on the measured results of capacitive IBC channel. Baluns and balun boards used in our measurements have the parasitic common-mode capacitances, ranging from 1.1 to 32 pF, which affects the measured transmission level of the IBC channel, leading to a significant difference of about 40 dB.
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paper_title: Effect of transformer symmetry on intrabody communication channel measurements using grounded instruments

paper_content:

Transformers with one winding terminal symmetrical with respect to ground (capacitances between their terminals and ground are the same) are referred to as balun transformers, and are often used for decoupling in the measurements of the intrabody communication (IBC) system transmission characteristics. We measured IBC system amplitude and phase transmission characteristics using three types of galvanic decouplers: non-symmetric RF transformers, balun transformers with center tap grounded and balun transformers with center tap floating. Four possible electrode configurations (AA, AB, BA, and BB) and four electrode arrangement (GSGS, GSSG, SGGS, and SGSG), result in a total of 16 measurement scenarios for each of three measurement setups. We showed that the change in the measured amplitude for different signal and ground electrode arrangements while measuring with non-symmetric transformers is influenced by the transformer symmetry to the ground, and not the capacitive intrabody communication transmission characteristics. The change of the amplitude in case symmetric balun transformers are used is negligible for practical purposes.
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paper_title: Channel Modeling of Miniaturized Battery-Powered Capacitive Human Body Communication Systems

paper_content:

Objective: The purpose of this contribution is to estimate the path loss of capacitive human body communication (HBC) systems under practical conditions. Methods: Most prior work utilizes large grounded instruments to perform path loss measurements, resulting in overly optimistic path loss estimates for wearable HBC devices. In this paper, small battery-powered transmitter and receiver devices are implemented to measure path loss under realistic assumptions. A hybrid electrostatic finite element method simulation model is presented that validates measurements and enables rapid and accurate characterization of future capacitive HBC systems. Results: Measurements from form-factor-accurate prototypes reveal path loss results between 31.7 and 42.2 dB from 20 to 150 MHz. Simulation results matched measurements within 2.5 dB. Comeasurements using large grounded benchtop vector network analyzer (VNA) and large battery-powered spectrum analyzer (SA) underestimate path loss by up to 33.6 and 8.2 dB, respectively. Measurements utilizing a VNA with baluns, or large battery-powered SAs with baluns still underestimate path loss by up to 24.3 and 6.7 dB, respectively. Conclusion: Measurements of path loss in capacitive HBC systems strongly depend on instrumentation configurations. It is thus imperative to simulate or measure path loss in capacitive HBC systems utilizing realistic geometries and grounding configurations. Significance: HBC has a great potential for many emerging wearable devices and applications; accurate path loss estimation will improve system-level design leading to viable products.
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Title: A Review on Human Body Communication: Signal Propagation Model, Communication Performance, and Experimental Issues

Section 1: Introduction
Description 1: This section introduces the significance of continuous health monitoring, discusses the limitations of traditional communication techniques for Body Area Networks (BANs), and highlights the potential benefits and characteristics of Human Body Communication (HBC).

Section 2: The History of Electrical Property and Human Tissue
Description 2: This section reviews the historical developments related to the electrical properties of human tissues and their relevance to HBC. It covers early research on tissue response to electrical stimuli and the progression towards using the human body for data transmission.

Section 3: Capacitive Coupling HBC
Description 3: This section presents the concept, principles, and initial implementations of capacitive coupling HBC, including its advantages and challenges.

Section 4: Galvanic Coupling HBC
Description 4: This section discusses the principles and initial implementations of galvanic coupling HBC, highlighting its potential for stable and reliable data transmission, especially for implantable devices.

Section 5: Electrical Properties of Human Tissues and HBC Signal Propagation Models
Description 5: This section explores the signal propagation models in HBC systems based on the electrical properties of human tissues, including numerical and analytical models.

Section 6: Channel Characteristics and Communication Performance of HBC Systems
Description 6: This section examines the channel characteristics crucial for data transmission in HBC systems and discusses the selection of transmission parameters to optimize communication performance.

Section 7: Applications of HBC
Description 7: This section outlines various healthcare applications of HBC prototypes, including physiological parameter measurement and data transmission for wearable and implantable devices.

Section 8: Safety Considerations and Experimental Issues
Description 8: This section details safety guidelines, electrode usage, grounding strategies, and other experimental issues to ensure safe and accurate in vivo HBC experiments.

Section 9: Conclusions and Future Studies
Description 9: This section summarizes the key points discussed in the paper, the current state of HBC, and proposes future research directions to address existing challenges and enhance HBC system performance.