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首页> 外文学位 >Study of efficient link adaptation schemes in wireless orthogonal frequency division multiplexing (OFDM) systems.
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Study of efficient link adaptation schemes in wireless orthogonal frequency division multiplexing (OFDM) systems.

机译：无线正交频分复用（OFDM）系统中有效链路自适应方案的研究。

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摘要

Wireless communication systems require high spectral efficiency and throughput in order to be cost-effective. Link adaptation schemes are known to be a good solution to achieve this goal. However, the necessity of additional information or increased complexity prevents these schemes from being implemented. In this context, research on resource allocation based on different constraints, such as complexity or feedback, is important.;The major contribution of this dissertation is the development of three novel techniques to enhance performance in practical implementations of the adaptive OFDM systems. This dissertation first introduces a new multiuser OFDM system to enhance performance in the low SNR regime. In this scheme, multiuser diversity can be efficiently amplified from random power allocation and opportunistic scheduling. Higher spectral efficiency can be achieved without an increase of complexity or feedback amount compared to conventional multiuser OFDM systems using equal power allocation. This dissertation also presents a modified multi-mode power loading scheme. A modified multi-mode power loading scheme can circumvent the limit of current multi-mode power loading schemes by significantly reducing search amount from 2N -- 1 to N, where N is the number of subcarriers. Finally, this dissertation has introduced adaptive OFDM systems using channel gain order information in limited feedback environments. Adaptive OFDM systems using the order mapping technique achieve comparable performance to conventional adaptive OFDM systems in terms of bit error rate and average spectral efficiency, while the amount of feedback is significantly reduced. Furthermore, by simply exploiting order mapping and interpolation, the analyzing technique circumvents the practical shortcomings of previous limited feedback techniques for OFDM systems.
机译：无线通信系统要求高频谱效率和吞吐量，以便具有成本效益。众所周知，链路自适应方案是实现该目标的良好解决方案。但是，附加信息的必要性或复杂性的增加阻止了这些方案的实施。在这种情况下，研究基于复杂性或反馈等不同约束条件的资源分配非常重要。本论文的主要贡献是开发了三种新颖的技术来提高自适应OFDM系统的实际性能。本文首先介绍了一种新的多用户OFDM系统，以提高低信噪比系统的性能。在该方案中，可以从随机功率分配和机会调度中有效地放大多用户分集。与使用相等功率分配的常规多用户OFDM系统相比，可以在不增加复杂性或反馈量的情况下实现更高的频谱效率。本文还提出了一种改进的多模式功率加载方案。修改后的多模式功率加载方案可以通过将搜索量从2N-1减少到N，其中N是子载波的数量，从而规避当前多模式功率加载方案的限制。最后，本文介绍了在有限反馈环境下使用信道增益阶数信息的自适应OFDM系统。就比特错误率和平均频谱效率而言，使用阶数映射技术的自适应OFDM系统可实现与传统自适应OFDM系统相当的性能，而反馈量则大大减少。此外，通过简单地利用阶数映射和内插，该分析技术规避了先前对于OFDM系统的有限反馈技术的实际缺点。

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  • 作者

    Choi, Eun Ho.;

  • 作者单位

    The University of Texas at Austin.;

  • 授予单位 The University of Texas at Austin.;
  • 学科 Engineering Electronics and Electrical.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 126 p.
  • 总页数 126
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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