Changcai Han

Shandong University, Chi-nan-shih, Shandong Sheng, China

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Publications (5)0 Total impact

  • Changcai Han, Dongfeng Yuan
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    ABSTRACT: An optimized power allocation scheme is proposed to compensate for the diversity loss and decrease the error propagation due to the group interference suppression and cancellation (G-ISC) algorithm in multilayered space-time trellis codes (ML-STTC). In the proposed scheme, with high probabilities, the signals in the first group can be correctly detected and their interference to other groups can be cancelled perfectly, which in turn facilitates the detection of the signals in other groups. Simulation results reveal the optimized scheme is adaptive to signal-to-noise ratio (SNR) and can achieve significant performance improvement without adding much delay and complexity.
    Wireless Communications, Networking and Mobile Computing, 2005. Proceedings. 2005 International Conference on; 10/2005
  • Changcai Han, Dongfeng Yuan, Xiangming Yu
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    ABSTRACT: Two novel kinds of unequal error protection (UEP) schemes using turbo codes combined with embedded zerotree wavelet (EZW) coded image transmission are proposed. According to the characteristics of the EZW coded bit stream, substreams are obtained by dividing the EZW coded bit stream into several segments. Then, the substreams with more importance are better protected using greater transmission power or turbo codes with more decoding iterations, while the less important substreams use lower power or turbo codes with fewer iterations. Simulation results demonstrate how the UEP schemes outperform the equal error protection (EEP) scheme in terms of peak signal-to-noise ratio (PSNR). Furthermore, another new way to save the transmission power is presented, in which the time delay can be greatly reduced while the quality of the image is guaranteed.
    Communications, Circuits and Systems, 2005. Proceedings. 2005 International Conference on; 06/2005
  • Changcai Han, Dongfeng Yuan
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    ABSTRACT: Hierarchical multimedia transmission in multiple-input and multiple-output (MIMO) system is researched. In MIMO system, the structure of multilayered Space-time Trellis codes (ML-STTC) has been proposed by combining array processing with Space-time Trellis code (STTC), the complexity of which is dramatically reduced by partitioning the transmit antennas into several layers. In this paper, a system architecture based on ML-STTC is constructed for image transmission, which performs as a compromise between data rate and reliability. In this architecture, the progressive data stream coded by set partitioning in hierarchical trees (SPIHT) is divided into several sub-streams according to their importance. Then a novel unequal error protection (UEP) scheme integrated with ML-STTC is proposed by optimizing the sub-stream allocation. Further more, the UEP scheme is strengthened by the ordered array processing at the receiver. In this way, the peak signal-to-noise ratio (PSNR) performance can be significantly enhanced in an environment with a moderate range of signal-to-noise ratio (SNR). In addition, the proposed transmission architecture and hierarchical transmission schemes can easily be extended to video communication systems with MPEG-4 or H.264 etc.
    Proc SPIE 01/2005;
  • Changcai Han, Dongfeng Yuan
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    ABSTRACT: The group detection algorithms for multilayered space-time trellis codes (ML-STTC), which combine space-time trellis code (STTC) and Bell Laboratories Space-Time (BLAST), are researched. According to the minimum mean square error (MMSE) detection algorithm for BLAST, the matrix of linear combination coefficients suitable for ML-STTC is drawn, and then the group interference MMSE suppression and cancellation algorithm is proposed. Simulation results show the modified detection algorithm can significantly improve the power-efficiency of the system at low signal-to-noise ratio (SNR)
    IEEE Technology and Society Magazine - IEEE TECHNOL SOC MAG. 01/2005;
  • Changcai Han, Dongfeng Yuan
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    ABSTRACT: A new scheme integrating variable-rate channel coding with the multilayered space-time trellis codes (ML-STTC), is proposed to compensate for the performance loss due to the limited diversity gain of the firstly-detected layer in the group interference suppression and cancellation algorithm at the receiver. In the proposed scheme, the code rate of the channel coding in each layer is adaptive to the diversity gain of this layer, with intent to guarantee the performance of the first layer which suffers from diversity loss. In this way, the error propagation is reduced and the overall performance is improved.
    Computational Intelligence and Security, International Conference, CIS 2005, Xi'an, China, December 15-19, 2005, Proceedings, Part II; 01/2005

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Institutions

  • 2005
    • Shandong University
      • School of Information Science and Engineering
      Chi-nan-shih, Shandong Sheng, China