Measurement And Modeling Of Wireless Channel In High Frequency Indoor Wireless Body Area Network

Wireless body area network(WBAN)is a wireless communication technology,which can monitor and record human health information for a long time.It not only can be widely used in the field of health care,but also has a broad applications in daily life,consumption,entertainment,sports and other industries,and most of these applications occur in indoor environments.Since the propagation characteristics of wireless channel are the key to design communication systems,it is of great significance to carry out the research on the propagation characteristics of wireless channels in indoor WBAN scenarios.At present,there are abundant studies on WBAN wireless channel propagation characteristics of low frequency band(Sub-6GHz)at domestic and abroad,while the researches on the propagation characteristics of high-frequency wireless channels are few.In addition,with the access of massive devices in the future and the increasing demand for service quality and instant messaging from users,low-frequency spectrum resources will become increasingly scarce,which will make it inevitable to explore and utilize high-frequency spectrum resources.Therefore,this thesis carries out wireless channel measurement experiments for the indoor WBAN scenarios at 10 GHz and obtains a large amount of measured data.Based on the measured data,the propagation characteristics of indoor WBAN wireless channels are studied.The main contributions include:(1)For the influence of body angle on the propagation characteristics of WBAN wireless channel in office environment,the channel characteristics are measured and studied in this scenario.A channel measurement system has been set up for indoor office WBAN environment.Channel measurement activities have been carried out for scenes with body angle changes at the center frequency of 10 GHz,and the extensive channel measured data has been obtained.Based on the measured data,the path loss,the shadow effect and the root mean square(RMS)delay spread of the10 GHz are present,and a novel path loss model with the body angle is proposed,which utilizes the body angle factor to correct the path loss caused by the change of body angle.Research results show that the path loss exponent has a quadratic function relationship with the body angle,the relationship between the path loss caused by the body angle(PBA)and the body angle can be expressed by a trigonometric function with a coefficient,which has a monotonously decreasing exponential function relationship with the distance between the receiving and sending ends.In addition,another big indoor office environment is measured to verify the applicability of the proposed model in different indoor environments.(2)For the influence of antenna height on the propagation characteristics of WBAN wireless channel in office environment,the channel characteristics are measured and studied in this scenario.A channel measurement system has been set up for indoor office WBAN environment.Channel measurement activities have been carried out for scenes with antenna height change in the central frequency of 10 GHz,and the extensive channel measured data has been obtained.Based on the measured data,the statistical characteristics of large-scale fading were present,and a path loss model with height impact was proposed to the antenna height change at the transmitter.The model uses the height factor to correct the path loss introduced by the antenna height change.Research results show that the path loss exponent has a quadratic function relationship with the antenna height and the relationship between the path loss caused by the antenna height(PLH)at the receiving end and the antenna height can be expressed as a quadratic function with coefficients.(3)For the influence of antenna angle on the propagation characteristics of WBAN wireless channel in hospital room and corridor environment,the channel characteristics are measured and studied in this scene.A channel measurement system has been set up for hospital room and corridor WBAN environment.Channel measurement activities have been carried out for scenes with antenna angle change at center frequency of 10 GHz,and the extensive channel measured data has been obtained.Based on the measured data in the hospital room and corridor scenarios,a novel statistical path loss model with the angle factor of receiving antenna(called as AAF)were present,where AAF is used to describe the effect caused by change of the angle of a wearable or handheld device on the human body.Research results show that the relationship between the AAF and the antenna angle can be expressed by a trigonometric function with a coefficient.In addition,a novel model for estimating the RMS delay spread is presented,along with the statistical characteristics of the RMS delay spread in two scenarios.In the model,the RMS delay spread is described as a linear function of the path loss,and a normal stochastic variable is introduced and utilized to characterize the deviation of the measured RMS delay spread from the linear function.Finally,the validity and applicability of the proposed model are verified by simulating the measured and simulated values in different hospital environments.