Ultra-wideband (UWB) is a wireless system which transmits signals across a much wider frequency spectrum than traditional wireless systems. The impulse radio (IR) UWB technique uses ultra-short duration pulses of nanoseconds or less. The objective of this thesis is to provide the design, implementation and testing of the timing recovery between the transmitter and receiver of the recently emerging differential code-shifted reference (DCSR) Impulse radio (IR) ultra-wideband (UWB) system. A new non-coherent energy detection based technique and its algorithm are proposed for timing recovery by means of a phase-locked loop (PLL) circuit. Simulations are presented first to verify the proposed algorithm. Then, it is implemented and tested in the Lattice ECP2 field-programmable gate array (FPGA) evaluation board with VHDL codes (a VHSIC hardware description language). The simulation and implementation results show that the proposed timing recovery scheme can be effectively achieved without much error.

This thesis explores the design of fast-settling pulse generators and pulsed low noise amplifiers (LNAs) for Ultra-Wideband (UWB) applications. These components are critical in pulsed UWB transceivers, and a high energy efficiency is sought without adversely affecting RF performance and functionality. To this end, new pulse generators with a subnanosecond settling time and a low energy consumption of only a few picojoules per pulse are targeted. Moreover, a novel pulsed LNA is investigated for a low power consumption that can be scaled with the duty cycle. First, an energy-efficient tunable pulse generator is proposed for high-data-rate 3.1-10.6 GHz UWB applications. A current-starved ring oscillator is quickly switched on and off, and the amplitude envelope is shaped using a passive attenuator. The energy consumption per pulse is below 4.2 pJ while the pulse amplitude is 150 mV, yielding a high energy efficiency. A quadrature pulse generator is then presented for 22-29 GHz UWB applications with a settling time below 0.5 ns. An inductor-capacitor (LC) oscillator is quickly switched on and off with a new technique, and the amplitude envelope is shaped using a variable passive attenuator. The energy consumption per pulse is only 6.2 pJ, and the pulse amplitude is more than 240 mV, yielding the highest energy efficiency reported to date in CMOS. Next, a 3-10 GHz pulsed ring oscillator that offers direct quadrature phase modulation is demonstrated. Current impulses are injected into the oscillator to enable fast startup and implement quadrature phase modulation. The energy consumption and voltage swing varies from 13 pJ and 300 mV at 3 GHz to 18 pJ and 200 mV at 10 GHz respectively, yielding a high energy efficiency. Lastly, a fast switching noise cancelling LNA is proposed for 3.1-10.6 GHz UWB applications that settles within 1.3 ns for switching speeds as high as 200 MHz. Inductive peaking is introduced in the noise cancelling topology to achieve a sub-4dB flat noise figure and a high gain of 16.6 dB for frequencies up to 10 GHz. The average power consumption is also below 10 mW with a 50% duty cycle clock. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2011-08-23 15:29:58.93

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This thesis investigates omnidirectional and directional ultra wideband (UWB) antennas for communication and microwave imaging applications. To reduce interference with existing technologies, monopole antennas with efficient band-stop functions are introduced. Single and double slots acting as series resonators are used. Reduction in the antenna gain in the stop-band regions of about 19.5 dB is achieved. Central metal removal and ground plane size effects on the antenna performance are investigated. To eliminate signal distortion caused by such monopole antennas, phase centre behaviour over the entire frequency band of operation is investigated at different principle planes, which have not been done before. This study will also show how these antennas act in different communication scenarios and where the radiation will be coming from at different frequencies. The effect of including different slots with different shapes on the performance of phase centre of these antennas is also investigated. Different methods to minimize the antenna phase centre movement are studied. Novel microstrip antennas with UWB impedance and radiation pattern bandwidth and low cross polarization components are introduced to work over the frequency band from 3 to 20 GHz. The antennas introduced are double-layer structures in which the radiator is sandwiched between two identical partial ground planes or a partial ground plane is sandwiched between two radiators. Results show a significant reduction in the cross polarization components at all frequencies. A novel high gain UWB Vee dipole antenna with a UWB coaxial balun feed is introduced to cover the existing and future UWB communication applications. Different type of loadings such as a reflecting ground below the antenna, a dielectric sleeve over the UWB balun and conical dielectrics between the Vee plates are also used and studied that show enhanced gains and lower sidelobes. A miniaturized-type UWB Vee dipole antenna is also investigated for microwave imaging applications. The antenna has a small radiation aperture which makes it a good candidate for array type applications. Full wave analysis of studied antennas are done using Ansoft HFSS, finite-element-methods based software. Experimental investigations are done to confirm the accuracy of simulated results.

In most wireless communications research, the channel models considered experience less severe fading than the classic Rayleigh fading case. In this thesis, however, we investigate MIMO channels where the fading is more severe. In these environments, we show that the coefficient of variation of the channel amplitudes is a good predictor of the link mutual information, for a variety of models. We propose a novel channel model for severely fading channels based on the complex multivariate t distribution. For this model, we are able to compute exact results for the ergodic mutual information and approximations to the outage probabilities for the mutual information. Applications of this work include wireless sensors, RF tagging, land-mobile, indoor-mobile, ground-penetrating radar, and ionospheric radio links. Finally, we point out that the methodology can also be extended to evaluate the mutual information of a cellular MIMO link and the performance of various MIMO receivers in a cellular scenario. In these cellular applications, the channel itself is not severely fading but the multivariate t distribution can be applied to model the effects of intercellular interference.

This thesis investigates omnidirectional and directional ultra wideband (UWB) antennas for communication and microwave imaging applications. To reduce interference with existing technologies, monopole antennas with efficient band-stop functions are introduced. Single and double slots acting as series resonators are used. Reduction in the antenna gain in the stop-band regions of about 19.5 dB is achieved. Central metal removal and ground plane size effects on the antenna performance are investigated. To eliminate signal distortion caused by such monopole antennas, phase centre behaviour over the entire frequency band of operation is investigated at different principle planes, which have not been done before. This study will also show how these antennas act in different communication scenarios and where the radiation will be coming from at different frequencies. The effect of including different slots with different shapes on the performance of phase centre of these antennas is also investigated. Different methods to minimize the antenna phase centre movement are studied. Novel microstrip antennas with UWB impedance and radiation pattern bandwidth and low cross polarization components are introduced to work over the frequency band from 3 to 20 GHz. The antennas introduced are double-layer structures in which the radiator is sandwiched between two identical partial ground planes or a partial ground plane is sandwiched between two radiators. Results show a significant reduction in the cross polarization components at all frequencies. A novel high gain UWB Vee dipole antenna with a UWB coaxial balun feed is introduced to cover the existing and future UWB communication applications. Different type of loadings such as a reflecting ground below the antenna, a dielectric sleeve over the UWB balun and conical dielectrics between the Vee plates are also used and studied that show enhanced gains and lower sidelobes. A miniaturized-type UWB Vee dipole antenna is also investigated for microwave imaging applications. The antenna has a small radiation aperture which makes it a good candidate for array type applications. Full wave analysis of studied antennas are done using Ansoft HFSS, finite-element-methods based software. Experimental investigations are done to confirm the accuracy of simulated results.

Ultra-wideband (UWB) antennas are one of the most important elements for UWB systems. With the release of the 3.1 - 10.6 GHz band, applications for short-range and high-bandwidth handheld devices are primary research areas in UWB systems. Therefore, the realization of UWB antennas in printed-circuit technologies within relatively small substrate areas is of primary importance. This thesis focuses on the design of a new UWB antenna based on coplanar technology. Compared with microstrip circuitry, coplanar technology achieves easier fabrication and wider antenna bandwidth. Two professional full-wave field solver software packages, HFSS and MEFiSTo-3D, are used as analysis tools to obtain antenna performances. A new printed-circuit antenna in coplanar technology for UWB systems is introduced. The frequency of operation is 3.1 GHz to 10.6 GHz with a VSWR < 2. Nearly omni-directional characteristics in vertical polarization are demonstrated at selected frequencies. Relatively good group delay characteristics are obtained and compare well with other published UWB antenna designs.

For low data rate ultra-wideband (UWB) communication systems employing non-coherent detection and autocorrelation detection schemes, timing of integration region significantly affects their error rate performance. Time-of-arrival (TOA) estimation of the first channel tap is also the foundation of the UWB based ranging applications. In this thesis, a data-aided, autocorrelation based timing and synchronization method is developed. First, estimation of the optimal integration region, i.e., the initial point and the length of the integration, using the new timing method is presented. It is shown that the proposed method enhances the error rate performance compared to non-optimal integration region-determining methods. After that, TOA estimation using the proposed timing method is studied for the dual pulse (DP) signal structure. The performance improvement of this approach over the conventional energy detection based method is demonstrated via simulation.

In this thesis, single carrier block transmission with frequency-domain equalization (SC-FDE) is proposed as an alternative physical layer solution for IEEE 802.15.3a Ultra¬wideband (UWB) communications to meet the high data rate and low complexity requirement. The performance of SC-FDE over UWB channels are analyzed, simulated and compared to that of the two currently existing physical layer solutions: the single carrier UWB using the direct-sequence (DS) technology and the multiband UWB utilizing the orthogonal frequency division complexing (OFDM). We show the superiority of SC-FDE over both IR-UWB and OFDM-UWB, especially when implementation issues such as low complexity and low power consumption are taken into consideration. Based on the proposed SC-FDE UWB, novel schemes are carried out to address the physical layer design issues. A low complexity frequency-domain channel estimation scheme is proposed. A novel time division multiple access (TDMA) scheme is proposed for high-speed SC-FDE UWB to address the multiple access issue. Furthermore, a novel transmitter pulse shaping design method is proposed to fit the FCC mask and introduce spectral nulls at the interference frequency band to limit the narrow band interference (NBI). In addition, the effects of imperfect channel estimation, carrier frequency offset (CFO) and sampling timing offset (STO) on the performance of SC-FDE over UWB channels are also investigated.

Ultra wideband (UWB) systems have the potential for extremely high data rate transmission, accurate ranging and positioning. In order to build systems that realize all the potential of UWB, it is first required to understand LT B propagation and the channel properties arising from the propagation. One of the key objectives of this thesis is to explore the characteristics of the UWB indoor channel. Through extensive time domain measurement, the channel reciprocity, spatial correlation, body shadow effect and temporal variation are investigated. Firstly, the existence of channel reciprocity is verified in both baseband and bandpass channels (from 4 GHz to 8 GHz). and channel reciprocity is demonstrated to be frequency independent and distance independent. Secondly, the spatial correlation is investigated on a two dimensional grid, and has been found to follow the trend of a two dimensional Bessel function as spatial distance increases. Thirdly. the interference of the received power and RMS delay spread due to body shadow effect is studied, indicating that the UWB system is highly robust to body shadowing as compared to narrowband systems. Finally. - extensive measurements of the UWB channel's temporal variation in a modern office building under diversified sets of conditions are conducted. A real time measurement is highly robust, to body shadowing as compared to narrowband systems. Finally. extensive measurements of the UWB channel's temporal variation in a modern office building under diversified sets of conditions are conducted. A real time measurement campaign involving mobile scatterers was performed in a typical office environment, hallway environment and lobby environment, to investigate the signal strength fluctuation, temporal correlation and Doppler spread. The analysis of the measurement results provide useful information for UN B system design. transceiver implementation and performance evaluation. The other goal of the thesis is to demonstrate the implementation of the transmitted reference pulse cluster (TRPC) receiver prototype. This prototype modulates data with binary phase shift keyed pulses. communicates over a wireless link using UWB antennas and a wideband direct conversion front-.end. and samples the auto-correlation output of the received signal for demodulation. Commercial off the shelf components are used to build the receiver, and design con¬siderations are introduced for each part of the receiver in detail.