Study On The Multipath Propagation Characteristics Of UWB Signals In The Indoor Short-range Environment For The Internet Of Things

Recently, the IoT(Internet of Things) with the main feature of information perception has been aroused broad attention, and has been seen as the world’s third wave of the information industry following Computers and the Internet. UWB(Ultra-wideband) technology is considered as one of the most competitive and promising technologies in indoor short-range wireless communication because of its low system consumption, high transmission rate and strong penetration performance and so on. The propagation characteristics of UWB is the important part of UWB channel theory. The study of multipath propagation has considerable theoretical and practical interest. In this thesis, the propagation characteristic of UWB signals in indoor short-range environment are discussed based on the time-domain ray tracing method, such as the received power, RMS(Root Mean Square) delay spread, instantaneous power delay profile and so on. The theoretical basis can be provided by these results for wireless communication network coverage and optimization of UWB signal in indoor short-range environment.The main contents and achievements are as follows:(1) The calculation method and deduction process of reflection coefficient, diffraction coefficient and transmission coefficient in time domain is summarized. Besides, the applicable scope and improvements between different calculation methods are analyzed.(2) The correctness and effectiveness of the time domain ray tracing method are validated by comparing the simulated results and the results given in published articles, which has good agreements.(3) The multipath propagation characteristics of UWB signals in indoor short-range environment with metallic furniture are studied considering the practical value. The innovation of the simulation is that metallic furniture can be seen as good conductors, which make the transmission paths hardly penetrate because of the “skin effect”, then, the contribution of diffraction paths in NLOS(Non-Line-of-Sight) range is raised. Therefore, the multipath propagation characteristics of UWB signals can be effectively studied considering the direct rays, reflection, diffraction and transmission after introducing metallic furniture. Some propagation parameters are obtained in the simulation, such as the received power, instantaneous power delay profile, RMS delay spread, multipath information and so on. The results show that the received power and RMS delay spread are reduced as the existence of metallic furniture. The multi-reflection and diffraction are important in NLOS which can’t be ignored and the power delay profile becomes narrower in NLOS.(4) In addition, considering the complexity of the simulation, the propagation characteristics of UWB signals in the indoor short-range office environment are simulated and analyzed based on the time-domain ray tracing method in NLOS range and which are compared with each other in LOS(Line-of-Sight) range. It turns out that the received power is subjected to uniform distribution and the variety of received power is smaller in LOS range. The multipath arrival distribution is dispersive in NLOS range. The pulse interval should be increased due to the RMS delay spread become larger in NLOS range.