WBAN Channel Modeling Based On Different Human Body Parameters At Millimeter-wave Band

The wireless body area network(WBAN)is a body-centric communication network.Its structure is composed of sensor nodes distributed on the surface of the human body or inside the body.Its function is to monitor human health information in real-time.Due to the increasing demand for transmission rates,people have begun to attach importance to human body area networks operating in the millimeter-wave(mm Wave)band.Since the on-body propagation of mm Wave is greatly affected by human parameters,this thesis analyzes the variation of path loss with different human parameters.First of all,the effects of tissue property in on-body communications were investigated in this thesis.To simplify the human body modeling,homogeneous human models were constructed for different frequencies and their accuracies were discussed.It turned out that from the path loss point of view,muscle equivalent model provides a good approximation for low frequency propagation while skin equivalent model is more accurate at high frequency.Then,the variation of path loss for the belt-to-chest link as the result of tissue property changes was examined.The mean and standard deviation of path loss exponent was presented from which the limits of path loss can be determined.Results showed that tissue property has larger impact at low frequency.Next,the influence of different body size parameters on human channels was investigated at 28 GHz.First,the propagation model of creeping wave on a cylindrical surface was described and measurements on cylindrical phantom were carried out to verify this model,the variation of power decay exponent of creeping wave with the radius of curvature were also discussed.Then,statistical simulations were performed on a number of human models with different heights and subject-specific path loss models of the waist-to-chest link for two different body shapes(standard shape and fat shape)were established.The characteristics of mm Wave on-body propagation were analyzed based on creeping wave theory and it was found that the path loss exponent decreases with the increase of body height in mm Wave band.Finally,the accuracies of simulation and established model were verified by comparing with measured results.Finally,on-body propagation channel characteristics of human dynamic links were investigated at 28 GHz.In order achieve this,one cycle of human walking and running has been divided into 15 human models with different postures.These models were statistically simulated,the path loss fluctuations of the waist-hand,waist-to-head,waistto-knee,and waist-to-chest links under two kinds of motions were discussed,and the path loss model of the dynamic human channel was established.Then,the multipath effects of dynamic links were considered,and the impulse response models of four propagation links were established.Finally,the accuracy of the impulse response model was verified based on the root mean square(RMS)delay extension.