Zhenqi Chen

Tsinghua University, Peping, Beijing, China

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Publications (3)0 Total impact

  • Zhenqi Chen, R. Yao, Zihua Guo
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    ABSTRACT: The electromagnetic transmission phenomenon is one of the most important parts of propagation modeling of UWB signals in the indoor environment. However, in previous work there has not been an efficient solution for the transmission of UWB signals. In this paper, we develop an analytical time-domain solution of a transmitted electric field through a lossy dielectric slab excited by an oblique incident plane wave. This solution is derived from the inverse Laplace transform of refraction coefficients at both surfaces of the slab and propagation losses in the slab. Based on the solution, a detailed investigation is presented on the transmitted field waveform for UWB signals passing through lossy dielectric slabs in varied scenarios of an indoor environment. Finally, we discuss the transmission loss of different slabs in the indoor environment and how to efficiently apply our solution efficiently in modeling the UWB propagation.
    Vehicular Technology Conference, 2004. VTC2004-Fall. 2004 IEEE 60th; 10/2004
  • Weiyu Xu, Zhenqi Chen, Zihua Guo, R. Yao
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    ABSTRACT: We propose a novel reduced-complexity maximum-likelihood (ML) detector for multi-user impulse radio ultra-wideband (UWB) signals in multi-path channels. By utilizing the unique trellis feature of a multi-user impulse radio UWB signal, and introducing a novel combined stack and Viterbi based trellis search (CSVS) algorithm, the proposed detector is optimal and enjoys much lower computation complexity compared with the brute-force search based ML detector. Simulation results show that the proposed detector achieves much better performance than the conventional simple matched filter UWB detector.
    Radio and Wireless Conference, 2004 IEEE; 10/2004
  • Richard Yao, Wenwu Zhu, Zhenqi Chen
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    ABSTRACT: In this paper, an efficient time-domain ray model is developed for ultra wideband (UWB) indoor multipath propagation channels. This model is based on a time-domain uniform geometrical theory of diffraction (TD-UTD) technique, which consists of three basic ray mechanisms of geometrical optics (GO) and UTD, i.e., directed ray, multi-reflected rays from lossy surfaces, and diffracted ray from lossy edges. The useful approximated analyses of TD multi-reflected rays with horizontal polarization and vertical polarization are provided. The TD diffraction coefficient is described. A software-based TD ray tracing tool has been developed to determine all paths of multiple reflections and diffractions, propagation delay of each path, pulse waveform and amplitude, and TD path loss. The simulation results in a typical office room are presented.
    Vehicular Technology Conference, 2003. VTC 2003-Fall. 2003 IEEE 58th; 11/2003