Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 37 for “"propagation environment"”.
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Adaptive matched field processing in an uncertain propagation environment
… degradation in performance in the presence of environmental mismatch. This sensitivity to environmental mismatch is of particular concern in problems such as long-range acoustic array processing in the ocean where the array processor's knowledge of the propagation characteristics of the ocean …
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A Ray-Based Investigation of the Statistical Characteristics and Efficient Representation of Multi-Antenna Communication Channels
… of wireless channels using a model of the propagation environment and are a low-cost alternative to direct measurements. We use ray tracing simulations to validate the statistical time and angle of arrival characteristics of an indoor multipath channel and compare model parameter estimates …
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Wireless Communication in Vehicles
… of the in-vehicle Electromagnetic (EM) wave propagation environment, and to demonstrate how this can be used to aid the deployment of wireless communication systems in vehicles. The fundamental characterisation of the in-vehicle EM wave propagation environment presented in this dissertation …
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Link Adaptation for Mitigating Earth-to-Space Propagation Effects on the NASA SCaN Testbed
In Earth-to-Space communications, well-known propagation effects such as path loss and atmospheric loss can lead to fluctuations in the strength of the communications link between a satellite and its ground station. Additionally, a less-often considered effect of shadowing due to the geometry of …
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A Comprehensive In-Building and Microcellular Wireless Communication System Design Tool
… are becoming increasingly prevalent in work environments. The need to quickly and efficiently provide in-building and microcellular coverage without sacrificing quality is critical to cellular and emerging personal communication system (PCS) operators. Traditionally, indoor wireless …
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Location Estimation in Wireless Communication Systems
… the performance is easily affected by the signal propagation environment. When the direct path between transmitter and receiver is obstructed, the signal measurement error for the localization process will increase significantly. Considering this problem, we first propose a novel algorithm which …
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ACCELERATED NOISE INTERFEROMETRY-BASED PASSIVE ACOUSTIC CHARACTERIZATION OF THE LITTORAL OCEAN
… acoustically in a surreptitious and environmentally friendly way using noise interferometry. Noise interferometry exploits ambient sound as a signal to probe the environment. Empirical acoustic Green's functions are retrieved from cross-correlations of diffuse noise that is measured …
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Synthesis of Optimal Arrays For MIMO and Diversity Systems
… given a specific power angular spectrum of the propagation environment. The method numerically constructs the eigenfunctions of the covariance operator for the scenario subject to constraints on the power radiated by each antenna as well as the level of supergain allowed in the solution. The …
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Microwave multipath resolution in microcellular channels
… measurements with site-specific radio wave propagation prediction techniques. A wide band spread spectrum measurement system was developed, and desirable measurement locations were selected on the Virginia Tech campus. These measurements are designed togo beyond statistical characterizations …
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Feasibility of Smart Antennas for the Small Wireless Terminals
… of a transmit smart antenna in a real propagation environment. These include vector channel measurements for narrowband and wideband signals, channel reciprocity, and effect of antenna element spacing on diversity performance. Real-time demonstrations of transmit smart antenna have been …
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Site-specific propagation prediction for wireless in-building personal communication system design
… describes a geometrical optics model to predict propagation in buildings for personal communication system (PCS) design. Background on the growth of wireless communications is given, and the importance of accurate propagation models is discussed. The peculiarities of propagation in mobile and …
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Rss Based Localization In A Rayleigh Fading Environment
… we assume fading is Rayleigh and that the propagation constant is constant but unknown. Also, we assume that modulation is spread spectrum and that either the sensors or agents are capable of resolving multipath components down to the chip level and are capable of measuring the received …
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Towards a Wireless Aircraft
… PhD Thesis lays out the main challenges of the propagation environment explaining that large sections of an aircraft may be highly resonant and explain- ing the difficulties this presents for wireless receivers. Modern wireless standards are explored and the question of how suitable they would …
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Foundations of Radio Frequency Transfer Learning
… they show limited adaptability to changes in the propagation environment and transmitter/receiver hardware, leading to significant performance degradation. Given the fluidity of modern communication environments, this rigidness has limited the widespread adoption of RFML solutions to date. …
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Laboratory and field trials evaluation of transmit delay Diversity applied to DVB-T/H networks
… are designed cost-effectively and with minimized environmental impact. The use of transmit diversity techniques with multiple antennas have long been proposed to improve the performance and capacity of wireless systems. Transmit diversity exploits the scattering effect inherent in the channel by …
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Investigation of Indoor Propagation Algorithms for Localization Purposes: Simulation and Measurements of Indoor Propagation Algorithms for Localization Applications using Wall Correction Factors, Local Mean Power Estimation and Ray Tracing Validations
… work is to enhance the awareness of the indoor propagation behaviour, by a set of investigations including simulations and measurements. These investigations include indoor propagation behaviour, local mean power estimation, proposing new indoor path loss model and introducing a case study on 60 …
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Channel Propagation Model for Train to Vehicle Alert System at 5.9 GHz using Dedicated Short Range Communication
… model of the train to vehicle communication environment that is proposed above, large-scale path loss and small scale fading will both be analyzed to characterize the propagation environment. Measurements were collected at TTCI in Pueblo Colorado to measure the received signal strength in a …
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Smart Base Station Antenna Performance for Several Scenarios - an Experimental and Modeling Investigation
… base antenna performance mechanisms for various environments is important to design cost effective systems and network. This dissertation focuses on the experimental characterization and modeling of the smart base station antenna performance for various propagation environment scenarios. An …
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Measurement System and Campaign for Characterizing the Theoretical Capacity and Cross-Correlation of Multiple-Input Multiple Output Indoor Wireless Channels
… through independent and spatially separated propagation channels. In more recent developments, space-time coding and array processing techniques use diversity concepts to resolve multiple independent streams of data and increase the potential data-rate. This new space-time research …
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Molecular Code Division Multiple Access: Gaussian Mixture Modeling
… communicate with each other in the same environment. A new channel model and detection technique along with a molecular-based access method, are proposed in here for communication between asynchronous users. In this work, the received molecular signal is modeled as a Gaussian mixture …
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