As a promising technology for body sensor networks, human body communication uses the human body as a transmission medium. To explore the propagation characteristics of multi-node human body communication, a non-uniform medium human body model is employed in this study to simulate the multi-node human communication channel at different distances based on finite difference time domain (FDTD) method. And the results demonstrate that the communication loss of multi-node human body will increase as the transmission distance goes longer. In-vivo experiments were carried out on the simulation models as well. The normalized received power was analyzed by using the maximum likelihood estimation (MLE) and the Akaike information criterion (AIC). Then it was further statistically analyzed by using different distribution models at 45MHz operating frequency, with multi-node communications measured within three meters. The maximum attenuation of the receiver power is only 6.7dB and the channel loss will increase with the node distance. By comparing the simulation and the measurement results, it is found that the two results have the consistent attenuation trend. By measurement, Frequency Shift Keying (FSK) data is transmitted at 3m and Bit Error Ratio (BER) ≤10^-5 for multi-node human body communication, which is thus verified to have certain reliability and stability as well as the feasibility.
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