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A study of the development of end-user computing in Hong Kong李國強, Lee, Kwok-keung, Roger. January 1991 (has links)
published_or_final_version / Business Administration / Master / Master of Business Administration
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Multi-user Non-Cooperative and Cooperative Systems with HARQRauf, Zahid January 2013 (has links)
The performance and reliability of wireless communication links can be improved by employing multiple antennas at both ends, thereby creating multiple-input multiple-output (MIMO) channels. However, once multiple co-channel users are added to the system it can be difficult to provide as many receive antennas as transmit antennas, resulting in a so-called overloaded (rank-deficient) system. Under overloaded conditions, maximum likelihood (ML) detection works well, but its exponential complexity prohibits its use and suboptimal linear detectors perform poorly.
In this thesis, new signal processing techniques for multi-user overloaded systems using hybrid automatic repeat request (HARQ) protocols are investigated. The HARQ retransmissions are used to form virtual receive antennas, which can efficiently transform an overloaded system into a critically loaded system (i.e. a system with an equal number of transmit and receive antennas).
In the first part of the thesis, a multi-user non-cooperative overloaded system is considered. At first, it is demonstrated that the suboptimal linear minimum mean square error (MMSE) detector leads to significant performance degradation compared to an ML detector for such systems. To overcome this drawback, two multi-user transmission schemes are proposed that work well under overloaded conditions. The proposed schemes allow us to apply linear multi-user detection (MUD) algorithms without requiring additional antennas or hardware chains. Monte-Carlo simulations demonstrate that the proposed schemes can result in significant gains in terms of bit-error-rate (BER) and dropped packet performance.
In the second part, the performance of multiple HARQ processes for a two-hop multi-source multi-relay decode-and-forward (DF) relaying network with no direct link are analyzed. Dealing with multiple HARQ processes at each relay, a retransmission scheme is proposed that utilizes virtual antennas to achieve increased receive diversity and improved throughput compared to traditional orthogonal (time division) retransmissions. A novel forwarding strategy at the relay(s) to destination link is proposed with the objective of further improving throughput. Finally, the end-to-end outage probability and throughput efficiency of the proposed retransmission and forwarding schemes are found analytically and confirmed with Monte-Carlo simulations.
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Spatial data : access and usability across the InternetLi, Chunsheng January 2002 (has links)
No description available.
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Modelling users by classification : an example-based approachFinlay, Janet Elizabeth January 1990 (has links)
No description available.
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The potential network effects of travellers' responses to travel demand management measuresMoyo, Norbert January 2001 (has links)
No description available.
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Understanding the role of information in the passenger rail industryMcLay, Graeme David January 2000 (has links)
No description available.
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Users involvement in environmental action : Some implications for theory and practiceAl-Yassin, M. M. H. January 1983 (has links)
No description available.
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A formal description method for user interfacesMarshall, L. S. January 1986 (has links)
No description available.
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A software environment for discrete event simulationWales, F. J. January 1986 (has links)
No description available.
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A user administered database systemRobinson, A. E. January 1985 (has links)
No description available.
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