Maximum Doppler diversity transmissions for high mobility systems with imperfect channel state information
Maximum Doppler diversity transmissions for high mobility systems with imperfect channel state information
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DOI：
10.1109/icc.2014.6884267
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发表时间：
2014-06
期刊：
影响因子：
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通讯作者：
Weixi Zhou;Jingxian Wu;P. Fan
中科院分区：
文献类型：
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作者：
Weixi Zhou;Jingxian Wu;P. Fan
研究了高移动性系统中存在非理想信道状态信息(CSI)时的最大多普勒分集传输问题。在高移动性系统中，由于快时变衰落，信道估计误差往往是不可避免的，并可能对系统性能产生重大影响。另一方面，快时变衰落引起的多普勒扩展引入了有利于系统性能的多普勒分集。通过推导解析式的符号错误率(SER)，研究了信道估计误差和多普勒分集之间的基本权衡，它将两者的影响统一在一个表达式中。研究表明，传统的最大比合并(MRC)接收机在存在信道估计误差的情况下不再是最优的。通过分析估计的信道系数的统计特性，提出了一种新的能够在非理想CSI条件下获取最大多普勒分集的最优接收机。然后，推导并评估新接收机的误码率。分析和仿真结果用于确定能够在多普勒分集和信道估计误差之间实现最佳折衷的系统参数。
This paper studies the maximum Doppler diversity transmissions in the presence of imperfect channel state information (CSI) in high mobility systems. Due to fast time-varying fading in high mobility systems, channel estimation error is usually inevitable and they might have significant impacts on system performance. On the other hand, Doppler spread caused by fast time-varying fading introduces Doppler diversity that can benefit system performance. The fundamental tradeoff between channel estimation errors and Doppler diversity are studied by deriving the analytical symbol error rate (SER), which captures both effects in a single expression. It is shown that conventional maximal ratio combining (MRC) receiver is no longer optimum with channel estimation errors. A new optimum receiver that can collect the maximum Doppler diversity with imperfect CSI is developed by analyzing the statistical properties of the estimated channel coefficients. The SER of the new receiver is then derived and evaluated. The analytical and simulation results are used to identify the system parameters that can render the optimum tradeoff between Doppler diversity and channel estimation error.