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OFDMA schemes with diversity in frequency-selective fading channels.

机译：在频率选择衰落信道中具有分集的OFDMA方案。

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摘要

By using sufficiently long prefix and orthogonal narrow-band sub-carriers with adaptive bit loading, orthogonal frequency-division multiple-access (OFDMA) can offer high bandwidth efficiency required for broadband wireless access communications in frequency-selective fading channels. However, when deep fading occurs in a frequency slot, it can create data loss in one or more sub-carriers. Diversity techniques could be used to enhance the performance of OFDMA in the presence of deep fades.; The research presented in this thesis aims to provide diversity in OFDMA for broadband wireless access communications in frequency-selective fading channels. First, the diversity characteristics in OFDMA are examined to establish the diversity equivalence in the time and frequency domains. Based on these characteristics, suitable techniques to achieve the full diversity gain in OFDMA are developed. When channel information is available to transmitters, a group-optimal adaptive-tone-diversity OFDMA (GO-ATD-OFDMA) scheme that combines adaptive diversity gain and bit loading, is proposed. It is shown that the GO-ATD-OFDMA can offer a better performance than the conventional time-domain Rake receiver. In the case of unavailable channel information, spreading is combined with diversity in the proposed group-spreading OFDMA (GS-OFDMA) scheme to provide both diversity protection and interference suppression. The GS-OFDMA has a comparable performance to the group-orthogonal multi-carrier code-division multiple-access (GO-MC-CDMA) scheme but with a reduced transmitted peak-to-average power ratio (PAR). Performance of the proposed schemes in terms of error rates, spectral efficiency, achievable system throughput, and computational complexity is investigated by analysis and simulations.
机译：通过使用具有自适应位负载的足够长的前缀和正交窄带子载波，正交频分多址（OFDMA）可以提供选频衰落信道中宽带无线接入通信所需的高带宽效率。然而，当深衰落发生在一个频率时隙中时，会在一个或多个子载波中造成数据丢失。在深衰落的情况下，可以使用分集技术来增强OFDMA的性能。本文提出的研究旨在为频率选择性衰落信道中的宽带无线接入通信提供OFDMA的多样性。首先，检查OFDMA中的分集特性以建立时域和频域的分集等效性。基于这些特征，开发了在OFDMA中实现全分集增益的合适技术。当信道信息可用于发射机时，提出了一种将自适应分集增益和比特负载相结合的组最优自适应音分集OFDMA（GO-ATD-OFDMA）方案。结果表明，GO-ATD-OFDMA可以提供比传统时域Rake接收机更好的性能。在信道信息不可用的情况下，在提议的组扩频OFDMA（GS-OFDMA）方案中，扩频与分集相结合，以提供分集保护和干扰抑制。 GS-OFDMA具有与群正交多载波码分多址（GO-MC-CDMA）方案相当的性能，但具有降低的发射峰均功率比（PAR）。通过分析和仿真研究了所提出方案在误码率，频谱效率，可达到的系统吞吐量和计算复杂度方面的性能。

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  • 作者

    Xu, Ying Lin.;

  • 作者单位

    McGill University (Canada).;

  • 授予单位 McGill University (Canada).;
  • 学科 Engineering Electronics and Electrical.
  • 学位 M.Eng.
  • 年度 2004
  • 页码 74 p.
  • 总页数 74
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 无线电电子学、电信技术;
  • 关键词

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