Institute for Systems Research Technical Reports

Permanent URI for this collectionhttp://hdl.handle.net/1903/4376

This archive contains a collection of reports generated by the faculty and students of the Institute for Systems Research (ISR), a permanent, interdisciplinary research unit in the A. James Clark School of Engineering at the University of Maryland. ISR-based projects are conducted through partnerships with industry and government, bringing together faculty and students from multiple academic departments and colleges across the university.

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Author: search.filters.author.Jiang, YiminSubject: search.filters.subject.Intelligent Signal Processing and Communications Systems

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    A Video Transmission System Based on Human Visual Model for Satellite Channel
    (1999) Gu, Junfeng; Jiang, Yimin; Baras, John S.; ISR; CSHCN
    This paper presents a practical architecture for joint source-channel coding of human visual model-based video transmission over satellite channel. Perceptual distortion model just-noticeable-distortion (JND) is applied to improve the subjective quality of compressed videos. 3-D wavelet decomposition can remove spatial and temporal redundancy and provide scalability of video quality.

    In order to conceal errors occurring under bad channel conditions, a novel slicing method and a joint source channel coding scenario that combines RCPC with CRC and utilizes the distortion information to allocate convolutional coding rates are proposed. A new performance index based on JND is proposed and used to evaluate the overall performance at different signal-to-noise ratios (SNR). Our system uses OQPSK modulation scheme.

    This paper has been submitted to Globecomm99, Rio de Janeiro, Brazil, December 5-9, 1999.

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    A Practical Transmission System Based on the Human Visual Model for Satellite Channels
    (1999) Gu, Junfeng; Jiang, Yimin; Baras, John S.; Baras, John S.; ISR; CSHCN
    This paper presents a practical architecture for joint source-channel coding of human visual model-based video transmission over a satellite channel. Perceptual distortion model just-noticeable-distortion (JND) is applied to improve the subjective quality of compressed videos. 3-D wavelet decomposition can remove spatial and temporal redundancy and provide the scalability of video quality.

    In order to conceal errors occurring under bad channel conditions, a novel slicing method and a joint source channel coding scenario that combines RCPC with CRC and utilizes the distortion information to allocate convolutional coding rates are proposed. A new performance index based on JND is proposed and used to evaluate the overall performance at different signal-to-noise ratios (SNR). Our system uses OQPSK modulation scheme.

    The research and scientific content in this material has been submitted to Globecom'99.
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    A Carrier Frequency Estimation Method of MPSK Signals and Its Systolic VLSI Implementation
    (1999) Jiang, Yimin; Ting, Wen-Chun; Verahrami, Farhad B.; Richmond, Robert L.; Baras, John S.; Baras, John S.; ISR; CSHCN
    In this paper we present an autocorrelation-based method for estimating the carrier frequency offset of an MPSK signal with random data modulation. Although autocorrelation-based techniques imply heavy usage of hardware resources, this technique is scalable and lends itself well to systolic VLSI implementations. The performance of the open-loop estimator presented is close to the Cramer-Rao lower bound (CRLB) for the frequency estimation from a block of random PSK symbols at low signal-to-noise (SNR) ratios. The estimator can be used in frequency acquisition of burst and continuous modems operating under low SNR and large frequency offset conditions.

    This paper has been submitted to 33rd Annual Conference on InformationSciences and Systems, March 17-19, 1999, John Hopkins University,Baltimore, Md.
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    Carrier Frequency Estimation of MPSK Modulated Signals
    (1999) Jiang, Yimin; Richmond, Robert L.; Baras, John S.; Baras, John S.; ISR; CSHCN
    In this paper we concentrate on MPSK carrier frequency estmation based on random data modulation. We present a fast, open-loop frequency estimation and tracking techinque, which combines a feedforward estimator stuctureand a recursive least square (RLS) predictor. It is suitable for the frequency estimation and large frequency acquisition and tracking required of burst mode satellite modems operating under the condition of low SNR and large burst-to-burst frequency offset. The performance of the estimator is analyzed in detail and simulation results are shown. Finally, the non-linear impact of data modulation removal methods is discussed. The estimator we derived is easily implemented with digital hardware.

    This paper has been submitted to the 1999 International Conferenceon Communications, June 6-10, 1999, Vancouver, Canada