The Research On Ultra-wideband Wireless Communications And Positioning Technology

Since the US FCC approved the limited use of Ultra Wideband (UWB) technology in 2002, communication systems that employ UWB signals have drawn considerable attention by the research institutions and large companies. Many research results on UWB technology have emerged and some successful experiments have demonstrated both at home and abroad. A number of vendors have introduced the UWB chips and related products already. UWB technology has numerous advantages, such as high temporal resolution, low power spectral density of emission signal, low system complexity, low-power consumption and precise positioning etc. In spite of the advantages of UWB, there are several fundamental and practical issues that need to be addressed to ensure the success of this technology in the wireless communication market. Accurate modeling of UWB channel, synchronization and rapid acquisition of the signal, practical receiver design, precise positioning implementation, coexistence with other services and handling the interference with other wireless systems are some of the issues that still require a great deal of investigation. In this paper, UWB wireless communication and positioning technologies were studied as it will be the mainstream technology for short-range wireless communication in future. Research mainly in the following four aspects:Firstly, the modulation, receiver technical and channel models of UWB technology were studied and simulated and rapid acquisition of UWB signal, positioning and applications were focused on.Secondly, rapid acquisition of the signal synchronization is a key technology for UWB wireless communication. As pulse width of UWB is very narrow and the energy of a single pulse is very small, it is difficult to achieve the required system performance when using the traditional technology at synchronization time, hardware-rate and the complexity. After the study of UWB communication, a new two-step rapid acquisition program "Energy Detect + Search" was developed. The acquire time the new method was derived. It can achieve rapid acquisition and avoid increasing the complexity at the same time by comparing and simulation. Thirdly, UWB technology has recently received significant attention for it can provide low-power high-precision relative positioning capabilities. In IR-UWB system centimeter ranging is possible due to extremely short duration of transmitted pulses. However, it is difficult to determine the first arrival of the direct path using the traditional positioning method in the intensive multi-path environment. So how to distinguish the direct path of the signal and determine the corresponding time parameter are the key issues of positioning. In order to determine the first arrival of the direct path, a high-precision positioning method based on BP neural network was presented in this paper. Simulation results show that the method can achieve high-precision positioning.Fourthly, unlike the traditional narrow-band wireless communication systems, UWB system can easily combine positioning and communication in unity. In this paper applications based on the UWB, such as robot location and tracking, mine underground positioning, and health surveillance at home have been studied. The feasibility of the program was analyzed.