Yan Xin

University of Iowa, Iowa City, IA, United States

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Publications (13)8.14 Total impact

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    ABSTRACT: We present a unified approach to designing space-time (ST) block codes using linear constellation precoding (LCP). Our designs are based either on parameterizations of unitary matrices, or on algebraic number-theoretic constructions. With an arbitrary number of N<sub>t</sub> transmit- and N<sub>r</sub> receive-antennas, ST-LCP achieves rate 1 symbol/s/Hz and enjoys diversity gain as high as N<sub>t</sub>N<sub>r</sub> over (possibly correlated) quasi-static and fast fading channels. As figures of merit, we use diversity and coding gains, as well as mutual information of the underlying multiple-input-multiple-output system. We show that over quadrature-amplitude modulation and pulse-amplitude modulation, our LCP achieves the upper bound on the coding gain of all linear precoders for certain values of N<sub>t</sub> and comes close to this upper bound for other values of N<sub>t</sub>, in both correlated and independent fading channels. Compared with existing ST block codes adhering to an orthogonal design (ST-OD), ST-LCP offers not only better performance, but also higher mutual information for N<sub>t</sub>>2. For decoding ST-LCP, we adopt the near-optimum sphere-decoding algorithm, as well as reduced-complexity suboptimum alternatives. Although ST-OD codes afford simpler decoding, the tradeoff between performance and rate versus complexity favors the ST-LCP codes when N<sub>t</sub>, N<sub>r</sub>, or the spectral efficiency of the system increase. Simulations corroborate our theoretical findings.
    IEEE Transactions on Wireless Communications 04/2003; · 2.42 Impact Factor
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    ABSTRACT: Orthogonal frequency-division multiplexing (OFDM) converts a frequency-selective fading channel into parallel flat-fading subchannels, thereby simplifying channel equalization and symbol decoding. However, OFDM's performance suffers from the loss of multipath diversity, and the inability to guarantee symbol detectability when channel s occur. We introduce a linear constellation precoded OFDM for wireless transmissions over frequency-selective fading channels. Exploiting the correlation structure of subchannels and choosing system parameters properly, we first perform an optimal subcarrier grouping to divide the set of subchannels into subsets. Within each subset, a linear constellation-specific precoder is then designed to maximize both diversity and coding gains. While greatly reducing the decoding complexity and simplifying the precoder design, subcarrier grouping enables the maximum possible diversity and coding gains. In addition to reduced complexity, the proposed system guarantees symbol detectability regardless of channel s, and does not reduce the transmission rate. Analytic evaluation and corroborating simulations reveal its performance merits.
    IEEE Transactions on Communications 04/2003; · 1.75 Impact Factor
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    ABSTRACT: This paper proposes novel space-time-frequency (STF) coding for multi-antenna orthogonal frequency-division multiplexing (OFDM) transmissions over frequency-selective Rayleigh fading channels. Incorporating subchannel grouping and choosing appropriate system parameters, we first convert our system into a set of group STF (GSTF) systems. This enables simplification of STF coding within each GSTF system. We derive design criteria for STF coding and exploit existing ST coding techniques to construct both STF block and trellis codes. The resulting codes are shown to be capable of achieving maximum diversity and coding gains, while affording low-complexity decoding. The performance merits of our design are confirmed by corroborating simulations and compared with existing alternatives.
    IEEE Transactions on Signal Processing 11/2002; · 2.81 Impact Factor
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    ABSTRACT: This paper proposes novel space-time-frequency (STF) block coding for multi-antenna OFDM transmissions over frequencyselective Rayleigh fading channels. Incorporating subcarrier group- ing and choosing appropriate system parameters, we first convert our system into a set of group STF (GSTF) systems. This enables simplification of STF block coding within each GSTF system. We derive design criteria for STF block coding, and exploit existing ST coding techniques to construct STF block codes. The resulting codes are shown capable of achieving both maximum diversity and coding gains, while affording low-complexity decoding. The performance merits of our design is confirmed by corroborating simulations, and .compared with existing alternatives.
    08/2002;
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    Yan Xin, G.B. Giannakis
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    ABSTRACT: We derive a layered space-time scheme for multi-antenna orthogonal frequency-division multiplexed transmissions over frequency-selective channels. Compared with existing alternatives, the proposed scheme can attain very high spectral efficiency as well as improved performance. Enhanced diversity gains document its superior performance that is also tested by simulation.
    IEEE Communications Letters 06/2002; · 1.16 Impact Factor
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    ABSTRACT: Recent theoretical and experimental studies have shown that with affordable complexity, layered space-time (LST) transmissions can attain very high spectral efficiency in a rich-scattering environment. In this paper, we propose a novel high rate linearly precoded LST system, which allows for any number of transmit and receive antennas, and offers flexibility in trading performance with bandwidth efficiency and decoding complexity. Even with sub-optimum decoding, the system enjoys considerable transmit diversity gains. Its superior performance over existing uncoded V-BLAST and linear dispersion (LD) codes is confirmed by simulations.
    Wireless Communications and Networking Conference, 2002. WCNC2002. 2002 IEEE; 04/2002
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    ABSTRACT: This paper proposes novel space-time-frequency (STF) block coding for multi-antenna OFDM transmissions over frequency-selective Rayleigh fading channels. Incorporating subcarrier grouping and choosing appropriate system parameters, we first convert our system into a set of group STF (GSTF) systems. This enables simplification of STF block coding within each GSTF system. We derive design criteria for STF block coding, and exploit existing ST coding techniques to construct STF block codes. The resulting codes are shown capable of achieving both maximum diversity and coding gains, while affording low-complexity decoding. The performance merits of our design are confirmed by corroborating simulations, and compared with existing alternatives.
    Acoustics, Speech, and Signal Processing, 2002. Proceedings. (ICASSP '02). IEEE International Conference on; 02/2002
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    ABSTRACT: A novel space-time-frequency (STF) trellis coding scheme is developed for multi-antenna OFDM transmissions over frequency-selective Rayleigh fading channels. Incorporating subcarrier grouping and choosing appropriate system parameters, we first convert our system into a set of group STF (GSTF) systems. This enables simplification of STF block coding within each GSTF system. We derive design criteria for STF trellis coding, and exploit existing ST trellis coding techniques to construct STF trellis codes. The resulting codes are shown capable of achieving maximum diversity gains, while affording low-complexity decoding. The performance merits of our design is confirmed by corroborating simulations, and compared with existing alternatives.
    Vehicular Technology Conference, 2002. VTC Spring 2002. IEEE 55th; 02/2002
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    ABSTRACT: We present a unified approach to constructing linear space-time (ST) block codes based on unitary constellation-rotating (ST-CR) precoders. We show that with an arbitrary number of M-transmit and N-receive antennas, ST-CR precoders achieve 1 symbol/sec rate and enjoy maximum diversity gain MN over both quasi-static and fast fading channels. We also compare real with complex rotations to delineate the tradeoff between performance and complexity. Based on a simplified decoder, we study diversity and coding gains as well as information-theoretic aspects of the proposed ST-CR scheme. Compared with ST orthogonally designed (ST-OD) codes, ST-CR precoding provides larger coding gain and maximum mutual information. Though ST-OD codes afford simpler decoding, the tradeoff between performance and rate versus complexity favors the ST-CR codes when M, N or the spectral efficiency of the system increase
    Acoustics, Speech, and Signal Processing, 2001. Proceedings. (ICASSP '01). 2001 IEEE International Conference on; 02/2001
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    ABSTRACT: We apply algebraic number theoretic tools to designing linear space-time constellation-rotating (ST-CR) block codes. With an arbitrary number of M transmit- and N receive-antennas, our ST-CR designs achieve a rate of 1 symbol/second and enjoy maximum diversity gains MN over quasi-static fading channels. When M is an Euler number, φ(P) for P≠0 (mod 4), or, when M=2<sup>m</sup> for some positive integer m, the designed ST-CR precoders also maximize coding gains over QAM constellations. When M takes other integer values, we construct a method to design precoders with large coding gains that can be computed explicitly. Simulations corroborate our theoretical findings
    Global Telecommunications Conference, 2001. GLOBECOM '01. IEEE; 02/2001
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    ABSTRACT: This paper introduces linear constellation precoding (LCP) for OFDM transmissions over frequency-selective fading channels. Exploiting the correlation structure of OFDM subchannels, and choosing system parameters properly, we first perform optimal subcarrier grouping to divide the set of correlated subchannels into subsets. Within each subset, a non-redundant constellation-specific unitary precoder is then designed to achieve maximum multipath diversity and coding gains. While greatly reducing the decoding complexity and simplifying the LCP design, subcarrier grouping offers optimal performance by maximizing multipath diversity and coding gains. In addition, the proposed system does not sacrifice the transmission rate. Analytic evaluation and corroborating simulations reveal its performance merits.
    Signals, Systems and Computers, 2001. Conference Record of the Thirty-Fifth Asilomar Conference on; 02/2001
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    ABSTRACT: In this paper, we analyze the performance of multiple-transmit/receive antenna systems with linear precoders. From the performance of these systems, we deduce design rules for linear precoders. Following the design rules, we prove the existence and derive linear unitary precoders achieving maximum diversity gain. Compared with existing real precoders, the novel unitary precoders offer the potential of larger coding gains. Simulations illustrate that the unitary precoders can achieve more than 1 dB coding gain over real precoders while they perform comparably to repeated transmissions, that consume larger amounts of bandwidth when two or three transmit antennas are utilized.
    Signals, Systems and Computers, 2000. Conference Record of the Thirty-Fourth Asilomar Conference on; 02/2000
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    ABSTRACT: We derive a layered space-time scheme for multi-antenna or-thogonal frequency-division multiplexed transmissions over frequency-selective channels. Compared with existing alter-natives, the proposed scheme can attain very high spectral efficiency as well as improved performance. Enhanced di-versity gains document its superior performance that is also tested by simulation.

Publication Stats

860 Citations
8.14 Total Impact Points

Institutions

  • 2002–2003
    • University of Iowa
      • Department of Electrical and Computer Engineering
      Iowa City, IA, United States
  • 2000–2002
    • University of Minnesota Twin Cities
      • Department of Electrical and Computer Engineering
      Minneapolis, MN, United States