Ultra Wide Band (UWB) is a new spectrum allocation which was recently approved by the Federal Communication Commission (FCC) and is under study in Europe and Asia. It has emerged as a solution to provide low complexity, low cost, low power consumption, and high-data-rate wireless connectivity devices entering the personal space. Any wireless system that has a fractional bandwidth greater than 20% and a total bandwidth larger than 500MHz enters in the UWB definition. At the emission level, UWB signals have a mask that limits its spectral power density to -41.3dBM/MHz between 3.1Ghz and 10.6GHz. There are two approaches that have been studied in order to use the 7.5Ghz allocated for UWB systems. First, OFDM techniques can be used to cover the entire spectrum; these techniques are called multi-band UWB. On the other hand, the second approach makes use of impulse radios which generate very-short-duration baseband pulses that occupy the whole spectrum. The objective of this thesis is to study, design, prototype, and test a UWB impulse radio using off-chip components. A Direct Sequence (DS) UWB transceiver architecture was selected. The transmitter uses first derivative Gaussian pulses that are modulated using a bi-phase modulation technique. The pulse rate of the system is 100MHz and the bit rates under investigation were 100Mbps, 50Mbps, 25Mbps, and 10Mbps. The transmitter and receiver were divided in functional blocks in order to execute system level simulations. The transmitter was implemented in both schematics and layout, and the UWB pulse generator block was constructed and tested in order to validate its functionality. On the other hand, the off-chip implementation of the receiver presented particular difficulties that made its construction not possible in this study. As a result, the blocks of the receiver were implemented in Matlab and the performance of the whole transceiver was estimated through numeric simulations. Finally, a case study for the multi-user capability of the system was presented.

The Ultra-Wideband (UWB) channel is a dense multipath channel. The system performance and design complexity issues of selective-Rake receiver (SRake) are studied. Rake receiver has difficulties achieving desired system performance in the dense multipath environment. The main ideas of SRake receiver are to obtain the SNR level on known multipath channel and determine the desired number of Rake fingers. In the implementation of the SRake, the CLEAN algorithm is used in selecting the paths with relatively high energy. We can improve the performance of SRake receiver by increasing the accuracy of path selection. By the property of local maximum peak within the smaller partition, Two-Stage CLEAN algorithm acquires the more accurate delay time of multipath. In order to mitigate the sidelobe effect and noise interference, the key assumption in the Deng¡¦s Modified CLEAN algorithm is that using average amplitude around the considered data change as the criterion to determine if the data value is a true path. In this thesis, we investigate CLEAN, Two-Stage CLEAN and Deng¡¦s Modified CLEAN algorithm in three different systems including UWB-Impulse Radio, Pulse Radar and DS-UWB. From the performance comparison, it can be seen that the Two-Stage CLEAN algorithm that has the highest accuracy of path selection in UWB system.