Spelling suggestions: "subject:"ultra wideband."" "subject:"ultra sideband.""
91 |
A Frequency-Modulated Continuous Wave-Based Boundary Detection System in a Small PCB ProfileAsgarian, Hamid R 01 December 2012 (has links) (PDF)
Falls are a cause of concern for the elderly because it can make them unable to call for help. A monitoring system can detect automatically their immobility and provide help to the elderly if they fall. Ultra-wide band signals for a monitoring system is an excellent choice since it has low enough power to not interfere with other medical and household electronics as well as being able to transmit data to a central monitoring unit. One part of this monitoring system is a boundary detection system used to verify that the monitoring system is not capturing events outside the monitoring region such as an event outside the house or in a neighboring room.
The work presented in the paper, “A Frequency-Modulated Continuous Wave-Based Boundary Detection System for Determination of Monitoring Region for an Indoor Ultra-Wideband Short Range Radar-Based Eldercare Monitoring System” has determined that a frequency modulated continuous wave (FMCW) based system is an acceptable solution for boundary detection. A FMCW system can measure distance with less than 10cm accuracy if the chosen spectrum bandwidth is 1GHz or more. This thesis presents the design of a low cost approach to small PCB footprint distance detection circuitry for the boundary detection system.
|
92 |
Dielectric resonator antenna design for lower-UWB wireless applicationsElmegri, Fauzi, See, Chan H., Abd-Alhameed, Raed, Excell, Peter S. January 2013 (has links)
No / A small dielectric resonator antenna has been designed for ultra wideband (UWB) communication system applications. The antenna element is a rectangular low permittivity ceramic block, with a dielectric constant of 9.4, and the modified T-shaped feed network includes a 50 ohm microstrip line to achieve strong coupling, and some bandwidth enhancement. The antenna performance is simulated and measured over a frequency band extending from 3100 MHz to 5500 MHz; the impedance bandwidth over this interval is 55.8% with VSWR <; 2, making the antenna suitable for UWB applications.
|
93 |
A design procedure for a 1-to-4 Ultra-Wideband Wilkinson power dividerAli, Ammar H., Abd-Alhameed, Raed, Hu, Yim Fun, Child, Mark B. 11 1900 (has links)
No / The design of a physically small, equal phase and equal power, 1-to-4 ultra-wideband Wilkinson power divider is presented. Initially, a 1-to-2 divider was designed and optimized for the 3.1 GHz-to-10.6 GHz range. The 1-to-4 divider was then realized using three 1-to-2 dividers, and further optimized for full band insertion loss, return loss, and isolation. The circuits were constructed using a 0.75 mm thick Rogers RO3035 substrate, and experimentally validated.
|
94 |
CROSS LAYER TECHNIQUES TO ENHANCE LINK PERFORMANCE IN WIRELESS NETWORKSSINGH, DAMANJIT January 2007 (has links)
No description available.
|
95 |
Joint scale-lag diversity in mobile wideband communicationsMargetts, Adam R. 24 August 2005 (has links)
No description available.
|
96 |
Ultra-Wideband Antennas for Medical Imaging and Communication ApplicationsJafari, Hamed Mazhab 08 1900 (has links)
<p> The allocation of 7.5 GHz of bandwidth by the Federal Communication Commission (FCC) for ultra-wideband (UWB) applications has provided an exciting and a challenging opportunity to design short range wireless communication and microwave imaging systems. To fully realize the potential of the UWB, communication and microwave imaging systems are required to operate over the entire UWB frequency band. The combination of the wide bandwidth requirement and the target application of the UWB systems have led to a surge of interest in designing of novel integrated circuits and antennas for the UWB applications. In any wireless communication and microwave imaging system, the antenna has a fundamental effect on the overall performance of the system, and as a result, it has attracted considerable research interest.</p> <p> This thesis focuses on the design of UWB antennas that are suitable for UWB cancer detection and wireless communication systems. Two planar antennas, one a
printed monopole antenna, and the other, a printed slot antenna fed with a coplanar waveguide, are presented in this work. First, the antennas have been designed to operate in air, making them suitable for the UWB wireless short range communication applications. Measurement and simulation results indicate that both antennas achieve input impedance matching in a bandwidth of more than 7.5 GHz. The effect on the input matching of the antennas due to the variation in their geometrical parameters has been studied and both antennas have been fully characterized in air. Next, the two antennas have been redesigned to operate in a coupling medium for medical imaging applications. Both antennas achieve return loss of less than -10 dB over the entire UWB spectrum. Also, the antennas have been fully characterized while operating in the coupling medium and in proximity to a human body model. Finally, a two-element antenna array, based on the printed monopole antenna and the printed slot antenna, in co- and cross-polarized array formation, has been designed. The tumor detection capabilities of all antenna arrays for different scenarios have been studied through electromagnetic simulation and measurements.</p> / Thesis / Master of Applied Science (MASc)
|
97 |
Ultra-Wideband, Low Power, Silicon Germanium Distributed AmplifiersEl-Badry, Ehab 09 1900 (has links)
<p> As modern digital communications evolve, the requirements imposed on the
systems than are required to transmit/receive the signals involved become more stringent.
Amplifiers are required to provide gain from low frequencies, sometimes down to DC, up
to high frequencies in the order of few to tens of gigahertz. Not only is the gainbandwidth
product to be enhanced, but also the amplifier should introduce minimal distortion to the signal and consume as low power as possible. </p> <p> Distributed amplification is a multi-stage broadband circuit technique that may provide such a function. In distributed amplifiers, inter-stage transmission lines provide the capability to reach higher operational frequencies by absorbing the parasitic capacitances of the transistors used. Unlike other broadband topologies that trade-off gain and bandwidth, distributed amplifiers do not, but rather, the trade-off is between gain and delay. As gain stages are added, the gain increases as the bandwidth remains the same but the signal delay is increased. </p> <p> This work considers the silicon germanium (SiGe) heterojunction bipolar transistor (HBT) implementation of distributed amplifiers. SiGe HBTs incorporate a thin SiGe base with Ge profiling to achieve high cut-off frequencies. SiGe BiCMOS
processes are silicon based and hence have the major advantage of integrability to the low
cost CMOS process unlike ill-V compound semiconductors. Hence, SiGe is a promising
technology capable of bridging the performance gap between silicon and m-v
semiconductors. </p> <p> The proposed amplifier achieves an approximately flat gain of 6.5 dB and a noise figure of 5.8-9 dB throughout the -3 dB passband of 10.5 GHz. The power consumed is
12.2 mW, significantly lower than previously published results by up to an order of
magnitude is some cases. The group delay of the amplifier was found to be
approximately constant in the passband at -60 ps. </p> <p> For the first time, temperature measurements are preformed on SiGe HBT DAs. Analysis show that the gain falls drastically with temperature increase due to deterioration in input matching caused by the significant change in the transistors input impedance with temperature. Similarly the NF, increases with temperature due to the decrease in gain. Moreover, noise analysis of SiGe HBT DAs is investigated, producing
simulations predicting the NF of the proposed amplifier giving insight as to how noise
may be reduced in future designs. </p> / Thesis / Master of Applied Science (MASc)
|
98 |
Ultra-Wideband Channel Modeling using Singularity Expansion MethodJoshi, Gaurav Gaurang 04 May 2006 (has links)
Ultra-wideband (UWB) communications is expected to revolutionize high data-rate, short-distance wireless communications, providing data-rates in excess of 100 Mbps. However, the wireless channel distorts the transmitted signal by dispersing the signal energy over time. This degrades the output signal-to-noise ratio (SNR) of a correlation based matched-filter receiver, limiting the achievable data-rate and user capacity. Most wideband channel models do not account for all the identified dispersion mechanisms namely the frequency dispersion, the resonant dispersion and the multipath dispersion.
The objective of this research is to model resonant dispersion based on the Singularity
Expansion Method (SEM) and provide guidelines for UWB receiver design to meet the data capacity. The original contribution of this research is a novel pole dispersion channel model that includes resonant dispersion characterization. An empirical investigation supports our claim that a correlation type matched-filter receiver using a template signal based on the pole dispersion channel model overcomes distortion related losses. Various physical mechanisms responsible for dispersion in UWB communication systems are described in detail. The applicability of the proposed dispersive channel model is evaluated using the optimal matched filter (OMF) receiver.
The SEM approach, which was originally proposed for target identification using short pulse radars, offers limited benefits of due to its susceptibility to noise. A combined fuzzy-statistical approach is proposed to improve the robustness of resonant dispersion channel modeling in presence of noise. A natural extension of this doctoral research is to improve buried landmine detection as well as breast tumor detection by applying statistical and fuzzy analysis to the backscatter response. Moreover, radar target identification using UWB short pulses stands to gain tremendously from this research. / Ph. D.
|
99 |
Interference Avoidance based Underlay Techniques for Dynamic Spectrum SharingMenon, Rekha 09 May 2007 (has links)
Dynamic spectrum sharing (DSS) is a new paradigm for spectrum allocation that is expected to lead to more efficient spectrum usage and alleviate the spectrum-scarcity that has been perceived in recent years. DSS refers to the opportunistic, dynamic, and uncoordinated use of the spectrum by multiple, possibly non-cooperating, systems. It allows bands which may be underutilized by incumbent or legacy systems to be shared by agile or cognitive radios on a ``do no harm" basis.
An ideal DSS technique is one which efficiently uses the allocated spectrum and maximizes the performance of the DSS network while causing no interference to the legacy radio system with which it coexists. We address this issue in our work by investigating desirable features for DSS with respect to the impact on a legacy radio system as well as the performance of a DSS network. It is found that ``ideal" DSS techniques with respect to both objectives are characterized by the removal of the strongest interferers in the system and averaging of the remaining interference. This motivates the use of an interference avoidance (IA) based underlay technique for DSS. The performance benefit provided by this technique, over an IA-based overlay technique, is shown to increase with the transmission bandwidth available to the DSS system. It is also shown that this technique is more robust to inaccuracies in the system knowledge required for implementing IA.
An example of an IA-based underlay technique is a spreading-sequence-based transmission scheme that employs sequence adaptation to avoid interference. We use game-theoretic tools to design such schemes for distributed or ad hoc networks. The designed schemes can also be used to avoid interfering with other agile or static radios. We then extend this work to Ultra Wideband systems which can maximally exploit the gains from the proposed scheme due to the large transmission bandwidths. / Ph. D.
|
100 |
Algorithms and Architectures for UWB Receiver DesignIbrahim, Jihad E. 26 March 2007 (has links)
Impulse-based Ultra Wideband (UWB) radio technology has recently gained significant research attention for various indoor ranging, sensing and communications applications due to the large amount of allocated bandwidth and desirable properties of UWB signals (e.g., improved timing resolution or multipath fading mitigation). However, most of the applications have focused on indoor environments where the UWB channel is characterized by tens to hundreds of resolvable multipath components. Such environments introduce tremendous complexity challenges to traditional radio designs in terms of signal detection and synchronization. Additionally, the extremely wide bandwidth and shared nature of the medium means that UWB receivers must contend with a variety of interference sources. Traditional interference mitigation techniques are not amenable to UWB due to the complexity of straight-forward translations to UWB bandwidths. Thus, signal detection, synchronization and interference mitigation are open research issues that must be met in order to exploit the potential benefits of UWB systems. This thesis seeks to address each of these three challenges by first examining and accurately characterizing common approaches borrowed from spread spectrum and then proposing new methods which provide an improved trade-off between complexity and performance. / Ph. D.
|
Page generated in 0.0336 seconds