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.
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Showing 1 to 15 of 15 for “"Telephone systems"”.
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Performance analysis of CDMA systems in multipath channels
… analysis of Code Division Multiple Access (COMA) systems in non-ideal conditions. Two benefits of CDMA include resistance to multipath fading and graceful performance degradation in the presence of multiple access interference. These benefits have made CDMA especially attractive for cellular …
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The evolution of the wireless equipment value chain
Mobile wireless telephone systems require enormous investments in land-based radio, transmission, and switching systems in order to provide the coverage and capacity to efficiently operate a regional or nationwide cellular phone network. This wireless equipment is manufactured by an oligopoly of …
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Design and Implementation of an FPGA-based Adaptive filter Single-User Receiver
… providers are continuously looking for better systems. The main focus of continued research has been to increase the quality of services and system capacity. The Code Division Multiple Access (CDMA) cellular system had been proposed for use as a new standard for cellular telephone systems. A …
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Bit error rate simulation enhancement and outage prediction in mobile communication systems
… simulating digital mobile radio communication systems. Internally generated two-ray Rayleigh fading channel models as well as imported spatially varying complex channel impulse responses can be utilized in simulations. Implementation of receiver timing jitter and timing recovery models, as well …
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Blind Estimation of Perceptual Quality for Modern Speech Communications
… were not experienced earlier with conventional telephone systems. Since perceived speech quality is a major contributor to the end user's perception of quality of service, speech quality estimation has become an important research field. In this dissertation, perceptual quality estimators are …
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Assignment of Spreading Codes in Code Division Multiple Access Radio Systems
… Sequence Code Division Multiple Access radio systems. Particular emphasis is given to Quasi-Synchronous Code Division Multiple Access. The frequency spectrum required for these systems depends on the length of the spreading code used. Frequency spectrum is an important and expensive resource …
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Die ontstaan en ontwikkeling van die Afrikaanssprekende Gereformeerde Kerke in die Goudveld (1946 – 1961) : ‘n historiese perspektief (Afrikaans)
… proper roads, communication networks like direct telephone systems, the lack of church buildings, manses, the long distances between the central point of worship and some visiting areas within the confinements of the congregation had necessarily complicated the task of the minister. Nevertheless, …
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Ultra Wideband Interference on Third-Generation Wireless Networks
… the low emissions mask protects incumbent systems operating in the same spectrum from being interfered with, while the wide bandwidth offers the possibility of high data rates, in excess of 250 Mbps. UWB has been regulated to operate in the 3.1 to 10.6 GHz portion of the spectrum, with an …
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Data mining, fraud detection and mobile telecommunications: call pattern analysis with unsupervised neural networks
Huge amounts of data are being collected as a result of the increased use of mobile telecommunications. Insight into information and knowledge derived from these databases can give operators a competitive edge in terms of customer care and retention, marketing and fraud detection. One of the …
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Linearity and monotonicity of a 10-bit, 125 MHz, segmented current steering digital to analog converter
The purpose of this research is to determine the linearity and monotonicity of the THS5651IDW digital to analog converter (DAC), a prototype of the future Texas Instruments TLV5651, 10-bit, 125 MHz communication DAC. Testing was conducted at the Texas Instruments facility on Forest Lane, Dallas, …
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System and Methods for Detecting Unwanted Voice Calls
Voice over IP (VoIP) is a key enabling technology for the migration of circuit-switched PSTN architectures to packet-based IP networks. However, this migration is successful only if the present problems in IP networks are addressed before deploying VoIP infrastructure on a large scale. One of the …
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Capacity and Throughput Optimization in Multi-cell 3G WCDMA Networks
User modeling enables in the computation of the traffic density in a cellular network, which can be used to optimize the placement of base stations and radio network controllers as well as to analyze the performance of resource management algorithms towards meeting the final goal: the calculation …