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 18 of 18 for “"Multiple-antenna systems"”.
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Multiple-antenna systems in ad-hoc wireless networks
… wireless networks as a function of the number of antennas per node, link-length, interferer density, and path-loss-exponent (an environmental parameter that determines signal decay with distance), under assumptions chosen for realistic implementability in the near future. These results improve our …
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Propagation models for multiple-antenna systems : methodology, measurements and statistics
… communications is towards utilization of multiple antenna systems. While techniques such as beam-forming and spatial diversity have been implemented for some time, the emergence of Multiple-Input Multiple-Output (MIMO) communications has increased commercial interest and development in …
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Analytical Framework for the Performance Analysis of Multiple Antenna Systems
There has been great interest in antenna array processing (diversity, beamforming, null steering, and spatial multiplexing) to enhance the received signal quality and the capacity of wireless communications systems. However, in order to properly exploit the characteristics of different array …
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Contribution to the characterization and evaluation of multiple antenna systems for communications: prototyping, propagation and antenna perspective
… opening new options for signal processing for antenna arrays. The main objective of this thesis has been to investigate the possibilities for radiocommunication systems that are based on the use of multiple antennas to take advantage of the available spatial diversity in the channel. Moreover, …
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The Impact of Channel Estimation Error on Space-Time Block and Trellis Codes in Flat and Frequency Selective Channels
Recently multiple antenna systems have received significant attention from researchers as a means to improve the energy and spectral efficiency of wireless systems. Among many classes of schemes, Space-Time Block codes (STBC) and Space-Time Trellis codes (STTC) have been the subject of many …
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Opportunistic resource allocation and relaying methods for quality of service in the downlink of future cellular wireless networks
… brink of a major change. New technologies called multiple antenna systems (MIMO) and orthogonal frequency division multiple access (OFDMA) will be put together in the deployment of the next generation of cellular standards known as 4G. Consumers can expect peak data rates up to 160 Mbps. If the …
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Transmit antenna selection in fading wireless communication systems
To address the drawbacks associated with multiple-input multiple-output (MIMO) systems, we propose the use of the transmit antenna selection technique. In transmit antenna selection, the best performing antenna(s) is selected from all the available transmit antennas for transmission. Transmit …
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Performance evaluation of cross-layer energy-efficient transmit antenna selection for spatial multiplexing systems
Abstract Multiple-input multiple-output (MIMO) and cognitive radio (CR) are key techniques for present and future high-speed wireless technologies. On the other hand, there are rising energy costs and greenhouse emissions associated with the provision of high-speed wireless communications. …
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Current and evolved physical layer concepts : potentials and limitations of mobile broadband wireless access
… limitations of current and future mobile radio systems for area-wide mobile broadband access. It describes and thoroughly analyzes the physical layer of the current Release 8 of the UMTS LTE mobile radio standard implemented as single-antenna system. Different novel modifications and alternative …
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Utilizing optimal nulling to increase the number of supported wireless users over conventional beamforming
… to the healthy growth of telecommunication systems that is needed to support high-density environments. Multiple-antenna systems are deployed at base stations to support multiple users simultaneously on the same frequency, taking advantage of beamforming spatial diversity. In this thesis, we …
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Transmit Diversity and its Application to Cooperative Networking
… layer model of these networks. We identify multiple antenna systems as a vital component of physical layer solutions. We first investigate the case of multiple antenna space-time coding techniques to achieve spatial diversity. We observe that when correlation between the antennas in a local …
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Fundamental Limits and Joint Design of Wireless Systems with Vector Antennas
Multiple-antenna systems have generated tremendous research interest in the recent past mainly because of their promise of significant gains in capacity and performance as compared to single-antenna systems. Most work on multiple antennas has focused on the design of coding and modulation schemes, …
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Experimental Investigation Of Ultrawideband Wireless Systems: Waveform Generation, Propagation Estimation, And Dispersion Compensation
… for the future high-speed wireless communication systems. Although this technology offers several unique advantages like robustness to fading, large channel capacity and strong anti-jamming ability, there are a number of practical challenges which are topics of current research. One key challenge …
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Improving the Performance of Wireless Systems via Selective Interference Nulling and Adaptive Medium Access Control Design
Escalating demands for high performance wireless systems requires the confluence of smart communication methods, network protocols and ongoing advances in fabrication technologies, in order to bring smaller form factor mobile handsets to market. On par with these trends, this thesis focuses on two …
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Analysis and Implementation of a Novel Single Channel Direction Finding Algorithm on a Software Radio Platform
A radio direction finding (DF) system is an antenna array and a receiver arranged in a combination to determine the azimuth angle of a distant emitter. Basically, all DF systems derive the emitter location from an initial determination of the angle-of-arrival (AOA). Radio direction finding …
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Capacity, coding and interference cancellation in multiuser multicarrier wireless communications systems
Multicarrier modulation and multiuser systems have generated a great deal of research during the last decade. Orthogonal Frequency Division Multiplexing (OFDM) is a multicarrier modulation generated with the inverse Discrete Fourier Transform, which has been adopted for standards in wireless and …
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Untersuchung und Realisierung von Mehrtorantennen zur Kanalkapazitätssteigerung von MIMO Systemen in Innenraumszenarien
… data rates for future wireless communication systems, which until today are limited to several tenths of Mbit/s (e.g. Wireless Local Area Network for IEEE 802.11a with 54MBit/s) is growing. In order to overcome this problem, new multiple antenna systems (MIMO: Multiple Output Multiple I nput) …
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MIMO Wireless Networks: Modeling and Optimization
… Such an approach can be achieved by the use of multiple antenna systems (also known as multiple-input multiple-output (MIMO) technology). The benefits of substantial improvements in capacity at no cost of additional spectrum and power have positioned MIMO as one of the breakthrough technologies …