Transceiver design for ultra-wideband communication systems

Ultra-Wideband (UWB) communication systems have great potentials in both military and commercial applications because of many of their attractive features: covertness, high data rate, fine delay resolution, minimal power consumption and low complexity. However, significant challenges exist, in UWB transceiver design and many research topics in this area remain open. There exist different types of UWB systems. Among them, we focus on impulse radio UWB in this dissertation. Accordingly, we address the issues in and propose solutions to efficient transmission; channel estimation, analog-to-digital conversion and receiver design.; When time hopping (TH) is coupled with impulse radio, multiuser communication is enabled. Noticing the unknown channel information for each user is embedded in statistics of received signals, we propose blind mean and covariance matching techniques to jointly estimate all users' channel parameters. The mean based approach has low complexity and is easy to implement while the covariance based approach can yield asymptotically minimum variance performance. By some modifications, they are extended to a TH-UWB system when hopping sequences vary across information symbols. Due to time varying codes, unique single-user solutions are derived in addition to multiuser counterparts.; To reduce the high price paid in statistical channel estimation, we propose a novel modulation diversity assisted UWB transmission scheme, where pulse position modulation and amplitude modulation are employed alternately on consecutive pulses. Signal models with and without inter-symbol interference are provided and the signal spectral characteristic is analyzed. Since consecutively received signals can be used as mutual references in detection, no explicit channel estimation is needed. Thus low complexity analog transceiver design is possible. If a block of received signals are processed, a high quality reference is obtained at a price of increased complexity. Adaptively updating the reference can yield performance close to a maximum likelihood channel estimator based detector.; Because a high sampling rate analog-to-digital converter (ADC) constitutes the major hurdle in UWB digital receivers, we analyze the effect of low resolution ADC on system performance in a transmitted-reference system with inter-pulse interference. Joint estimation and detection performance is analytically evaluated capturing the effects of ADC resolution, finite signal samples, and background noise.