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Achievable rates, optimal signalling schemes and resource allocation for fading wireless channels.

机译：无线信道衰落时可达到的速率，最佳信令方案和资源分配。

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摘要

The proliferation of services involving the transmission of high rate data traffic over wireless channels makes it essential to overcome the detrimental effects of the wireless medium, such as fading and multiuser interference. This thesis is devoted to obtaining optimal resource allocation policies which exploit the transmitters' and receiver's knowledge about the fading to the network's advantage, to attain information theoretic capacity limits of fading wireless channels.; The major focus of the thesis is on capacity results for fading code division multiple access (CDMA) channels, which have proved to be a robust way of combatting the multiuser interference in practical wireless networks. For these channels, we obtain the capacity region achievable with power control, as well as the power control policies that achieve the desired rate points on the capacity region. We provide practical one-user-at-a-time iterative algorithms to compute the optimal power distributions as functions of the fading. For the special case of sum capacity, some properties of the optimal policy, such as the number of simultaneously transmitting users, are obtained. We also investigate the effects of limited feedback on the capacity, and demonstrate that very coarse channel state information (CSI) is sufficient to benefit from power control as a means of increasing the capacity.; The selection of the signature sequences also plays an important role in determining the capacity of CDMA systems. This thesis addresses the problem of jointly optimizing the signature sequences and power levels to maximize the sum capacity. The resulting policies are shown to be simple, consisting of orthogonal transmissions in time or signal space, and requiring only local CSI. We also provide an iterative way of updating the joint resource allocation policy, and extend our results to asynchronous, and multi-antenna CDMA systems.; Rather than treating the received signal at the transmitters as interference, it is possible to treat it as free side information and use it for cooperation. The final part of the thesis provides power allocation policies for a fading Gaussian multiple access channel with user cooperation, which maximize the rates achievable by block Markov superposition coding, and also simplify the coding strategy.
机译：服务的激增涉及通过无线信道传输高速率数据流量，因此必须克服无线介质的不利影响，例如衰落和多用户干扰。本论文致力于获得最优的资源分配策略，该策略利用了发射机和接收机关于衰落对网络的优势的知识，以达到衰落无线信道的信息理论容量极限。论文的主要重点是衰落的码分多址（CDMA）信道的容量结果，事实证明这是在实际无线网络中抵抗多用户干扰的一种可靠方法。对于这些通道，我们获得功率控制可实现的容量区域，以及在容量区域上实现所需速率点的功率控制策略。我们提供实用的一次一次用户迭代算法，以计算作为衰落函数的最佳功率分布。对于总容量的特殊情况，可以获得最佳策略的某些属性，例如同时传输用户的数量。我们还研究了有限反馈对容量的影响，并证明非常粗糙的信道状态信息（CSI）足以从功率控制中受益，这是增加容量的一种手段。签名序列的选择在确定CDMA系统的容量中也起重要作用。本文解决了联合优化签名序列和功率电平以最大化总容量的问题。结果显示，策略很简单，包括时间或信号空间中的正交传输，并且仅需要本地CSI。我们还提供了一种更新联合资源分配策略的迭代方法，并将我们的结果扩展到异步和多天线CDMA系统。与其将发射机处的接收信号视为干扰，不如将其视为自由边信息并将其用于协作。本文的最后部分提供了一种在用户合作下衰落的高斯多址信道的功率分配策略，该策略最大化了块马尔可夫叠加编码所能达到的速率，并且简化了编码策略。

著录项

  • 作者

    Kaya, Onur.;

  • 作者单位

    University of Maryland, College Park.;

  • 授予单位 University of Maryland, College Park.;
  • 学科 Engineering Electronics and Electrical.
  • 学位 Ph.D.
  • 年度 2005
  • 页码 146 p.
  • 总页数 146
  • 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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