Browsing by Author "Jiang, Jing"

Now showing 1 - 6 of 6
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    BSML: A Binding Schema Markup Language for Data Interchange in Problem Solving Environments
    Verstak, Alex; Ramakrishnan, Naren; Watson, Layne T.; He, Jian; Shaffer, Clifford A.; Bae, Kyung Kyoon; Jiang, Jing; Tranter, William H.; Rappaport, Theodore S. (Hindawi, 2003-01-01)
    We describe a binding schema markup language (BSML) for describing data interchange between scientific codes. Such a facility is an important constituent of scientific problem solving environments (PSEs). BSML is designed to integrate with a PSE or application composition system that views model specification and execution as a problem of managing semistructured data. The data interchange problem is addressed by three techniques for processing semistructured data: validation, binding, and conversion. We present BSML and describe its application to a PSE for wireless communications system design.
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    Capacity-approaching data transmission in MIMO broadcast channels
    Jiang, Jing (Virginia Tech, 2004-06-30)
    This dissertation focuses on downlink multi-antenna transmission with packet scheduling in a wireless packet data network. The topic is viewed as a critical system design problem for future high-speed packet networks requiring extremely high spectral efficiency. Our aim is to illustrate the interaction between transmission schemes at the physical layer and scheduling algorithms at the medium access control (MAC) layer from a sum-capacity perspective. Various roles of multiple antennas are studied under channel-aware scheduling, including diversity, beamforming and spatial multiplexing. At a system performance level, our work shows that downlink throughput can be optimized by joint precoding across multiple transmit antennas and exploiting small-scale fading of distributed multiple input and multiple output (MIMO) channels. There are three major results in this dissertation. First, it is shown that over a MIMO Gaussian broadcast channel, and under channel-aware scheduling, open-loop transmit antenna diversity actually reduces the achievable sum rate. This reveals a negative interaction between open-loop antenna diversity and the closed-loop multiuser diversity through scheduling. Second, a suboptimal dirty paper coding (DPC) approach benefits greatly from multiuser diversity by an efficient packet scheduling algorithm. Performance analysis of a suboptimal greedy scheduling algorithm indicates that, compared with the receiver-centric V-BLAST method, it can achieve a much larger scheduling gain over a distributed MIMO channel. Further, pre-interference cancellation allows for transmissions free of error propagation. A practical solution, termed Tomlinson-Harashima precoding (THP), is studied under this suboptimal scheduling algorithm. Similar to V-BLAST, a reordering is applied to minimize the average error rate, which introduces only a negligible sum-rate loss in the scenarios investigated. Third, for an orthogonal frequency division multiplexing (OFDM) system using MIMO precoding, it is shown that a DPC-based approach is readily applicable and can be easily generalized to reduce the peak-to-average power ratio (PAR) up to 5 dB without affecting the receiver design. Simulations show that in an interference-limited multi-cell scenario, greater performance improvement can be achieved by interference avoidance through adaptive packet scheduling, rather than by interference diversity or averaging alone. These findings suggest that, coordinated with channel-aware scheduling, adaptive multiplexing in both spatial and frequency domains provides an attractive downlink solution from a total capacity point of view.
  • Dynamic Data Structures for a Direct Search Algorithm
    He, Jian; Watson, Layne T.; Ramakrishnan, Naren; Shaffer, Clifford A.; Verstak, Alex; Jiang, Jing; Bae, Kyung; Tranter, William H. (Department of Computer Science, Virginia Polytechnic Institute & State University, 2001)
    The DIRECT (DIviding RECTangles) algorithm of Jones, Perttunen, and Stuckman (1993), a variant of Lipschitzian methods for bound constrained global optimization, has proved effective even in higher dimensions. However, the performance of a DIRECT implementation in real applications depends on the characteristics of the objective function, the problem dimension, and the desired solution accuracy. Implementations with static data structures often fail in practice, since it is difficult to predict memory resource requirements in advance. This is especially critical in multidisciplinary engineering design applications, where the DIRECT optimization is just one small component of a much larger computation, and any component failure aborts the entire design process. To make the DIRECT global optimization algorithm efficient and robust on large-scale, multidisciplinary engineering problems, a set of dynamic data structures is proposed here to balance the memory requirements with execution time, while simultaneously adapting to arbitrary problem size. The focus of this paper is on design issues of the dynamic data structures, and related memory management strategies. Numerical computing techniques and modifications of Jones’ original DIRECT algorithm in terms of stopping rules and box selection rules are also explored. Performance studies are done for synthetic test problems with multiple local optima. Results for application to a site-specific system simulator for wireless communications systems (S4W) are also presented to demonstrate the effectiveness of the proposed dynamic data structures for an implementation of DIRECT.
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    Globally Optimal Transmitter Placement for Indoor Wireless Communication Systems
    He, Jian; Verstak, Alex; Watson, Layne T.; Stinson, C.A.; Ramakrishnan, Naren; Shaffer, Clifford A.; Rappaport, Theodore S.; Anderson, Christopher R.; Bae, Kyung; Jiang, Jing; Tranter, William H. (Department of Computer Science, Virginia Polytechnic Institute & State University, 2002-08-01)
    In this paper, a global optimization technique is applied to solve the optimal transmitter placement problem for indoor wireless systems. An efficient pattern search algorithm ---DIRECT (DIviding RECTangles) of Jones, Perttunen, and Stuckman(1993)---has been connected to a parallel 3D radio propagation ray tracing modeler running on a 200-node Beowulf cluster of Linux workstations. Surrogate functions for a parallel WCDMA (wideband code division multiple access) simulator were used to estimate the system performance for the global optimization algorithm. Power converage and BER(bit error rate) are considered as two different criteria for optimizing locations of a specified number of transmitters across the feasible region of the design space. This paper briefly describes the undrelying radio propagation and WCDMA simulations and focuses on the design issues of the optimization loop.
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    Linking East with West: Websites as a Public Relations Tool for American and Chinese Banks Operating in a Culturally-Evolving Chinese Society
    Jiang, Jing (Virginia Tech, 2002-06-13)
    In this thesis, three websites are explored in-depth and serve as a case study for an intercultural comparison of websites as public relations tools. The websites of Industrial and Commercial Bank of China (ICBC), Shanghai Pudong Development Bank (SPDB), and Citibank were evaluated for this specific study because they represent three models of current banks operating in a culturally-evolving Chinese society. The two-way symmetrical model of public relations and the personal influence model have provided basic framework for this thesis. To establish the two-way symmetrical public relations via the website, these three banks employ different public relations strategies due to the different organizational structure and operating systems. In addition, culture has played an important role for banks to build relationships with their various publics. Specifically, Confucian ideology, the foundation for Chinese culture, provides insights for this thesis. To cater to the publics, ICBC adhered more strictly to Chinese culture norms, while SPDB's website is a reflection of a hybrid of Western and Chinese culture. Moreover, although Citibank does not make many efforts to culturally cater to its Chinese publics, Citibank successfully built its reputation and image through building a business-oriented and expert website.
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    S4W: Globally Optimized Design of Wireless Communication Systems
    He, Jian; Verstak, Alex; Watson, Layne T.; Stinson, C.A.; Ramakrishnan, Naren; Shaffer, Clifford A.; Rappaport, Theodore S.; Anderson, Christopher R.; Bae, Kyung; Jiang, Jing; Tranter, William H. (Department of Computer Science, Virginia Polytechnic Institute & State University, 2002-07-01)
    In this paper, a global optimization technique is applied to solve the optimal transmitter placement problem for indoor wireless systems. An efficient pattern search algorithm -- DIRECT (DIviding RECTangles) of Jones,Perttunen, and Stuckman(1993)--has been connected to a parallel 3D radio propagation ray tracing modeler running on a 200 node. Beowulf cluster of Linux workstations. Surrogate functions for a parallel WCDMA (wideband code division multiple access) simulator were used to estimate the system performance for the global optimization algorithm. Power coverage and BER (bit error rate) are considered as two different criteria for optimizing locations of a specified number of transmitters across the feasible region of the design space. This paper briefly describes the underlying radio propagation and WCDMA simulations and focuses on the design issues of the optimization loop.