"Design and Simulation of Ultra Wideband Pulse Based Communication Systems"
Design and Simulation of Ultra Wideband Pulse Based Communication Systems
Sprache des Titels:
In this thesis pulse based Ultra Wideband (UWB) communication systems are investigated by means of hardware test-beds and simulation. The main focus is set on the development of phase modulated transmitted reference (PMTR) systems, which are newly introduced in the frame of this thesis. There are two major ultra wideband (UWB) system concepts. Carrier based ones which use orthogonal frequency division multiplex (OFDM) or direct sequence CDMA (DS-CDMA) and carrier-free or pulse based systems. These pulse based systems have many elementary advantages, like a very basic transmitter structure, and good immunity against the effects of non-linear components and the effects in multipath channels. The drawbacks are difficult synchronization, realization of broadband components, or the multipath energy capturing problem in the receiver. Part of this thesis is focused on the development of UWB hardware test-beds, with its broadband measurement and matching challenges. Pulse generators for pulses in the subnanosecond time domain and the according pulse shaping circuits for FCC compliant pulses are proposed. Pulse delay circuits for time modulation, broadband low noise amplifiers (LNA), antennas, and receiver components are proposed, with solutions for coherent and and non-coherent communication systems. A synchronization algorithm with its according hardware is presented for a time modulated and amplitude modulated pulse based system. For a better understanding of the features and problems of the UWB multipath channel, channel measurements were performed in an office and an industrial environment. The communication link for a cochlear implant is a perfect application for demonstrating non-coherent UWB pulse based systems. Additional research work is spent on pulse shape properties and on link budget analysis for UWB systems. The new and sophisticated PMTR systems proposed in this thesis are able to solve some of the typical problems of UWB systems.