A Survey on M2M Systems for mHealth: A Wireless Communications Perspective <s> HBC Propagation Model <s> As electronic devices become smaller, lower in power requirements, and less expensive, we have begun to adorn our bodies with personal information and communication appliances. Such devices include cellular phones, personal digital assistants (PDAs), pocket video games, and pagers. Currently there is no method for these devices to share data. Networking these devices can reduce functional I/O redundancies and allow new conveniences and services. The concept of Personal Area Networks (PANs) is presented to demonstrate how electronic devices on and near the human body can exchange digital information by capacitively coupling picoamp currents through the body. A low-frequency carrier (less than 1 megahertz) is used so no energy is propagated, minimizing remote eavesdropping and interference by neighboring PANs. A prototype pan system allows users to exchange electronic business cards by shaking hands. <s> BIB001 </s> A Survey on M2M Systems for mHealth: A Wireless Communications Perspective <s> HBC Propagation Model <s> Abstract Intrabody communication using the human body as the transmission medium enables wireless communication without emitting radio waves into the surrounding environment. Experimental results on signal transmission gain in the frequency range from 1 to 1000 kHz have shown that the two-electrode arrangement, 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 arrangement, in which all four electrodes are attached to the human body. In addition, calculated gains based on four-terminal circuit models of two different electrode arrangements agree with empirical results. The validity of these 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 arrangement is more suitable for high-speed intrabody communication devices than the four-electrode arrangement. Intrabody communication between two persons can be established by shaking hands, which have numerous practical applications, such as the exchange of personal data or e-cash among wearable PCs. <s> BIB002 </s> A Survey on M2M Systems for mHealth: A Wireless Communications Perspective <s> HBC Propagation Model <s> Using the human body as a transmission medium for electrical signals offers novel data communication in biomedical monitoring systems. In this paper, galvanic coupling is presented as a promising approach for wireless intra-body communication between on-body sensors. The human body is characterized as a transmission medium for electrical current by means of numerical simulations and measurements. Properties of dedicated tissue layers and geometrical body variations are investigated, and different electrodes are compared. The new intra-body communication technology has shown its feasibility in clinical trials. Excellent transmission was achieved between locations on the thorax with a typical signal-to-noise ratio (SNR) of 20 dB while the attenuation increased along the extremities. <s> BIB003 </s> A Survey on M2M Systems for mHealth: A Wireless Communications Perspective <s> HBC Propagation Model <s> Human Body Communication (HBC) is regarded as a novel transmission technology for Artificial Intelligent (AI) society. It is important to measure and analysis body channel characteristics and the results are significant for Integrated Circuit (IC) design of HBC. This paper proposed an improving electrode configuration which was used to couple signals to human body with capacitive coupling type. The body channel characteristics in frequency domain, in time domain, and with different digital modulation were taken into sight systemically by Vector Network Analyzer (VNA), Vector Signal Generator (VSG), Digital Signal Analyzer (DSA), Arbitrary Function Generator (AFG) and Oscilloscope. The bandpass filtering characteristic of body channel was measured, and the center frequency is about 30MHz. The capacitive characteristic of body channel was also measured, and the capacitive characteristic disappears gradually with frequency increasing. Besides, the spectrum profiles of body channel characteristics with Frequency Shift Keying (FSK) and On-Off Keying (OOK) modulation after 20cm HBC were measured. Error Vector Multitude (EVM) was measured with different bits Quadrature Amplitude Modulation (QAM) after 20cm HBC. <s> BIB004
Apart from the propagation of radio waves in human body, WBANs support HBC, based on data transmission by capacitive and galvanic coupling, as shown in BIB003 BIB002 BIB004 BIB001 . The HBC propagation characteristics are mainly determined through measurements aiming to study the electrical behavior of the human body. In BIB003 , it has been shown that the transmitted signal level experiences high variations at different locations of the body. For example, short-range links between devices placed on the thorax or on the limbs have shown excellent transmission characteristics, whereas high attenuations that prohibit long-distance transmissions have been measured for extremities and joints.