Wideband Channel Characteristics And Modeling Of Wave Propagation Based On Measurements

Mobile communication has gone deep into every aspect of people’s lives. However, it needs to be improved in some area, such as high-speed mobile communication, Device to Device (D2D) communication, etc. This thesis fo-cuses on the wireless channel of high-speed mobile communication and D2D communication. The research on wireless channels includes channel measure-ment and channel modeling. Wireless channel measurement and modeling are the fundamentals of system design, technology evaluation and device perfor-mance and conformance testing. Thus, taking the radio signal propagation theo-ry as background, this thesis dedicates to the investigation and research of wire-less channel models. Based on the channel measurements and theoretical analy-sis, some solid achievements have been obtained in this thesis. The work of this thesis can be categorized as two parts:First, channel measurement and channel modeling of high-speed railway in viaduct scenario have been done. In the first place, radio propagation environ-ment of high-speed railway are analyzed and summarized. Then it needs to transform existing measurement equipment to make it suit to collect data in high-speed railway scenario. After transformation, synchronization time of measurement equipment is very short, which can basically guarantee transmitter and receiver remain synchronized during the measurements. The results of ob-tained measurement data which were analyzed and processed are path loss, shadow fading (SF), delay spread (DS) and Doppler spectrum. Based on results of channel measurements, this thesis analyzes path loss model of high-speed railway in the existing literature. It can be found that some models are different from model obtained from measured data and these models are not applicable to measured scenario. Fortunately, there is one model which is suitable and this thesis recommends this model to simulate high-speed railway scenario. Root mean square (rms) DS is also obtained in this thesis and is different from results of measurement results in Europe. Doppler spectra presented in this thesis prove that it is right to take maximum Doppler frequency shift as Doppler frequency shift in the case of line of sight.Second, channel characteristics and channel modeling of D2D communica-tion have been done based on channel measurements. D2D communication is controlled by the cellular network in this thesis. The researchers of D2D com-munication usually adopt channel model designed for the conventional cellular communication and there is no channel model for D2D communication. Com-pared to the conventional cellular communication system, D2D communication has some features which make it not appropriate to directly reuse the conven-tional propagation models from the cellular communication scenarios. Based on these features, dedicated field channel measurements are conducted. Path loss, Ricean K-factor and delay are analyzed in this thesis. In scenarios which have many measurement lines, the high dependency of path loss on small scatters around communication devices in short distance is found and it is more accurate to model the path loss exponent as a random variable obeying Normal distribu-tion. Meanwhile, all parameters to get path loss model are given in this thesis. Both SF and Rician K factor obey Log-normal distribution. For the small scale fading, rms DS follows Log-logistic distribution in indoor scenario whereas it increases with the distance between the transmitter and receiver in outdoor sce-nario. Finally, the measurement data of other scenarios are analyzed. These findings can be used to model the propagation of the D2D communication in corresponding scenarios, and facilitate the technology evaluation and system op-timization in D2D communication.These are work and innovations of this thesis. It can be concluded that the measurement data and analysis results presented by the thesis will be supportive in the network planning and technique evaluation of future communication sys-tem.