Additional information
by Benjamin Waldmann (Author)
Over the last decades an ever growing demand for wireless localization systems for many different indoor and outdoor application scenarios could be observed. Applications range from crane and fork-lift positioning to RFID-like asset tracking and access control and many more. Especially indoor applications show severe performance degradation due to heavy multipath effects. Since the resolution of wireless localization systems for all kinds of modulation techniques is proportional to the applied signal bandwidth, systems using ultra-wideband signals offer an excellent potential for accurate indoor positioning. With the accredited bandwidth for UWB systems, an accuracy in the range of a few centimeters is possible. This thesis presents the analysis and design of a pulsed frequency modulated ultra-wideband system for high precision local positioning. Up to now, all commercial available systems are based on the usage of very narrow pulses to generate ultra-wideband signals. To overcome typical limitations of the pure impulse UWB technology, a novel system concept is presented in this work. It combines pulse technology with frequency modulated continuous wave radar technology by chopping the FMCW signal into short pulses. On the one hand this fulfills the UWB regulation requirements, and on the other hand precise control of the signal shape is given for the whole bandwidth. This allows the use of advanced synchronization and distance measurement approaches. The main emphasis of this work is the investigation and realization of this pulsed frequency modulated UWB positioning system. The PFM-UWB system is based on a well-known LPR system, which is extended to an UWB system. Theoretical calculations, simulations and measurements are used to define the system and evaluate its performance. With an implemented demonstrator system, a high accuracy in dense multipath indoor environments can be achieved. Conclusive measurements, that demonstrate the abilities of the developed positioning system, round off this work.
