X.-B. Yu

Nanjing University of Aeronautics & Astronautics, Nan-ching, Jiangsu Sheng, China

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Publications (2)1.44 Total impact

  • X.-B. Yu, S.-H. Leung, Q.-M. Zhu
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    ABSTRACT: The performance analysis of a space-time block coded multiple input multiple output system with variable-power (VP) adaptive modulation (AM) over Rician fading channels for imperfect channel state information is presented. The optimum switching thresholds for attaining maximum spectrum efficiency (SE) subject to a target bit error rate (BER) and an average power constraint are derived. In the derivation, a very tight BER expression of quadrature amplitude modulation (QAM) is used to develop a new power adaptation scheme that can fulfil the target BER even at low signal-to-noise ratio (SNR) and achieve higher SE than the scheme using the BER upper bound commonly adopted in the literature. The existence and uniqueness of the Lagrange multiplier used in the constrained optimisation are investigated. It is shown that the Lagrange multiplier is unique when it exists. By using the switching thresholds, the authors obtain closed-form expressions of SE and average BER of the system. Computer simulation shows that the theoretical analysis is in good agreement with simulation. The results show that the proposed VP-AM scheme provides better SE than the constant-power counterparts and the VP-AM scheme using the commonly used BER bound.
    IET Communications 01/2012; 6(12):1676-1684. · 0.72 Impact Factor
  • X.-B. Yu, S.-H. Leung, W.-K. Wong
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    ABSTRACT: The performance of multi-input multi-output (MIMO) systems with variable-power (VP) adaptive modulation (AM) and antenna selection (AS) over Rayleigh fading channels for both perfect and imperfect channel state information (CSI) is presented. In this study, the optimum fading gain switching thresholds for attaining maximum spectrum efficiency (SE) subject to a target bit error rate (BER) and an average power constraint are derived. It is shown that the Lagrange multiplier in the constrained SE optimisation is unique if the existence conditions for MIMO systems with transmit AS and receive maximal-ratio combining under perfect or imperfect CSI are satisfied. By using the switching thresholds, we obtain closed-form expressions of the SE and average BER for VP and constant-power (CP) systems. Simulation results for SE and BER are in good agreement with the theoretical analysis. The results show that the VP-AM system using AS with the derived VP control scheme provides better SE than the CP counterpart and the VP-AM system with space-time coding and can fulfil the target BER for different signal-to-noise ratios (SNRs).
    IET Communications 08/2011; · 0.72 Impact Factor

Publication Stats

1.44 Total Impact Points

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  • 2012
    • Nanjing University of Aeronautics & Astronautics
      Nan-ching, Jiangsu Sheng, China