ICI and ISI analysis and mitigation for OFDM systems with insufficient cyclic prefix in time-varying channels
ICI and ISI analysis and mitigation for OFDM systems with insufficient cyclic prefix in time-varying channels
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DOI：
10.1109/tce.2004.1355879
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发表时间：
2004-02-01
影响因子：
4.3
通讯作者：
Zhu, CT
中科院分区：
文献类型：
--
作者：
Chen, SP;Zhu, CT
在正交频分复用（OFDM）系统中，OFDM块期间的信道变化导致子载波之间的正交性损失，从而导致载波间干扰（ICI）。已经提出了许多方案来抑制ICI，但是它们计算复杂或者以牺牲带宽为代价。在某些情况下，例如高密度电视（HDTV）广播和卫星OFDM系统，非常长的延迟扩展造成信道长度超过中等循环前缀（CP）的信道长度的可能性，从而导致符号间干扰（ISI）和载波间干扰（ICI）。时域均衡器（TEQ）通常用于接收机中，以减少传输系统的整体响应的持续时间，从而最小化ISI和ICI。然而，TEQ的优化设计是一项艰巨的任务。由CP不足和信道变化引入的ICI是不同的，并且通常利用不同的方法来减轻它们。在本文中，我们提供了一个ICI和ISI在时域和频域分析OFDM系统在时变信道的CP不足。在此基础上，我们提出了一种迭代的方法来联合消除ICI和ISI，其复杂度是线性的OFDM符号长度。理论分析和仿真结果表明，该方法能有效地抑制信道变化和CP不足引起的ICI和ISI，并具有较高的带宽利用率。（一）.
Channel variation during an OFDM block leads to the loss of orthogonality among subcarriers, resulting in inter-carrier interference (ICI) in orthogonal frequency division multiplexing (OFDM) systems. Many schemes have been proposed to suppress ICI, but they are computationally complex or at the price of sacrificing bandwidth. In some cases, such as high-density television (HDTV) broadcasting and satellite OFDM systems, the very long delay spreads pose the possibility that the channel length exceeds that of the moderate cyclic prefix (CP), resulting in intersymbol interference (ISI) and intercarrier interference (ICI). A time-domain equalizer (TEQ) is usually used in the receiver to reduce the duration of the overall response of the transmission system, and therefore minimize the ISI and ICI. However, the optimum design of TEQ turns out to be a difficult task. The ICI's introduced by insufficient CP and channels variations are different and usually exploit different methods to mitigate them. In this paper, we provide an ICI and ISI analysis in time- and frequency- domain for OFDM systems with insufficient CP over time-variant channels. Basing on this analysis, we propose an iterative method for joint ICI and ISI cancellation whose complexity is linear in the OFDM symbol length. Theoretical analysis and simulation results indicate that the proposed method can effectively mitigate ICI and ISI introduced by channel variation and insufficient CP with high bandwidth efficiency.(1).