Research On Modeling And Fading Characteristics Of Human Communication Channels In Non-uniform Media

With the development of global aging,biomedical-related wearable devices are attracting more and more attention.As a new type of communication technology,human body area communication takes human body as the signal transmission medium.It connects various biosensor devices which embedded in vivo and in vitro to form a body area network that can deal with human body helth information.Human communication channel modeling is an essential-prerequisite for the human body area communication technology.A perfect human body channel model is necessary for study channel propagation characteristics.The main contents of this paper are based on the National Natural Science Foundation of China"Research on Dynamic Channel Propagation Characteristics of Human Body Communication Based on Inhomogeneous Medium Model"(No.61403366),Shenzhen Basic Research Project"The theoretical research and modeling analysis of the dynamic communication mechanism of wearable devices"(No.JCYJ20140417113430695).We focusing on multi-layer inhomogeneous media modeling and fading channel characteristics of the human body.The full text is organized as follows:(1)Based on the principle of finite difference time domain,we build an inhomogeneous medium model about the skin,fat,muscle;and bones.Based on the correlation of the human tissue permittivity and frequency,the biological medium Debye model is fitted.The signal propagation characteristics of four kinds(vitro-vitro,vitro-vivo,vivo-vitro and vivo-vivo)of implanted channels in the frequency which range from 1MHz to 100MHz were studied.The channel attenuation measurement scheme based on the design of pork is proposed;in addition,exploring human transmission channel using Balun isolated converter electrode "common ground" effect.(2)The transmitting electrode was implanted the head.The distribution of relative electric field intensity arounding human body,in vivo and in vitro with 45MHz communication frequency of brain-computer interface link was studied.The change of electric field of body surface at different phases of sine wave was analyzed.On this basis,the effects of different frequencies on the electric field distribution of the human body are also studied in sine wave 3MHz,45MHz,403.5MHz and 2400MHz.In addition,the amplitude attenuation and group delay characteristics of the head-heart,head-arm,head-leg link channel were studied.(3)A cylindrical shape of the human arm inhomogeneous medium model was proposed,including the forerm and upper arm,joint part.The dynamic channel fading of 0/180deg?150deg arm bend curvature was researched.And the channel attenuation measurement scheme which based on the human was designed.The effect of the chnnel transmission signal by the bending angle of the arm and the metal box was analysised.In the aspect of the establishment of human dynamic link,this paper established 32 frames of human walking posture model and studied the dynamic channel fading characteristics of the typical links of the human abdomen-head,abdomen-wrist and abdomen-ankle with the specific frequency.(4)This part studied on the performance of link budget,communication distance,transmission rate and the required transmission power of the actual human communication system.In addition,the system architecture design of the project "the human body image transmission system" is introduced.And on the aboved basis,the parameters of prototype image transmission rate,information error rate and etc were tested.The results show that the actual the image transmission effect is deal.At the end of this paper,the research results are summarized,and the future research direction is expected.