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Multiuser multirate DS-CDMA detection techniques in multipath fading channels.

机译：多径衰落信道中的多用户多速率DS-CDMA检测技术。

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摘要

Code division multiple access (CDMA) is a promising technique for wireless communication where multiple users share the same channel, but is subject to intersymbol interference (ISI), multiple access interference (MAI) and near-far effects under multipath channels. This thesis investigates various multirate multiuser detection techniques (MUD) to mitigate these interferences in multirate Direct Sequence (DS) CDMA communication systems over multipath Rayleigh fading channels.; A new decorrelator based successive interference cancellation (DBSIC) multiuser Rake receiver is proposed for asynchronous Variable Processing Gain (VPG) multirate DS-CDMA systems. By including a decorrelator on top of matched filtering (MF) at each stage of the conventional SIC to determine the user's signal to be used at the next cancellation stage, DBSIC improves the overall system performance at the expense of feasible additional complexity.; Bit-error-rate (BER) performance of DBSIC is presented using an analytical approach and simulations. DBSIC improvement over other commonly used suboptimum MUD such as the decorrelating, minimum mean-square-error (MMSE), SIC, parallel interference cancellation (PIC) and decorrelating decision-feedback (decorrelating DF) detectors is demonstrated under both perfect and imperfect channel estimation.; It is shown that DBSIC outperforms all other considered MUD in various multi-rate scenarios even when some physical users have increased data rates (i.e. heavier system's load in terms of the number of virtual users). It is observed that, while all the receivers suffer performance degradation under imperfect channel estimation, DBSIC still outperforms the other schemes. DBSIC effectiveness to combat MAI is also evaluated in terms of its asymptotic multiuser efficiency (AME). AME for DBSIC is derived and compared with that of conventional single-user MF, optimum, decorrelating and SIC receivers over AWGN and Rayleigh channels.; To combat effectively the effects of multipath propagation and MAI, most MUD require some channel state information (CSI). Their performances depend mainly on their ability to obtain an accurate estimation of the CSI they require. An adaptive MAI-resistant joint channel estimation and MUD method combining decision-directed and data-aided approaches is developed for asynchronous multirate CDMA systems. The effectiveness of this joint scheme is supported by results in terms of channel estimates MSE and BER performance.
机译：码分多址（CDMA）是一种有前途的无线通信技术，其中多个用户共享同一信道，但在多径信道下会受到符号间干扰（ISI），多址干扰（MAI）和远近影响。本文研究了各种多速率多用户检测技术（MUD），以减轻多径瑞利衰落信道上多速率直接序列（DS）CDMA通信系统中的这些干扰。针对异步可变处理增益（VPG）多速率DS-CDMA系统，提出了一种新的基于解相关器的连续干扰消除（DBSIC）多用户Rake接收机。通过在传统SIC的每个阶段的匹配滤波（MF）之上包括一个解相关器，以确定在下一个取消阶段要使用的用户信号，DBSIC改善了整个系统的性能，但以可行的额外复杂性为代价。 DBSIC的误码率（BER）性能是使用一种分析方法和模拟来表示的。在完美和不完美的信道估计下，证明了DBSIC对其他常用的次优MUD（例如去相关，最小均方误差（MMSE），SIC，并行干扰消除（PIC）和去相关决策反馈（去相关DF）检测器）的改进。;结果表明，即使在某些物理用户提高了数据速率（即就虚拟用户数量而言较重的系统负载）的情况下，DBSIC在各种多速率方案中也优于所有其他考虑的MUD。可以观察到，尽管所有接收器在不完善的信道估计下都会遭受性能下降，但DBSIC仍然优于其他方案。还通过渐近多用户效率（AME）评估了DBSIC对抗MAI的有效性。推导了DBSIC的AME，并将其与AWGN和Rayleigh信道上的传统单用户MF，最优，解相关和SIC接收器进行比较。为了有效应对多径传播和MAI的影响，大多数MUD都需要一些信道状态信息（CSI）。它们的性能主要取决于它们能否准确估计所需的CSI。针对异步多速率CDMA系统，开发了一种结合决策导向和数据辅助方法的自适应抗MAI联合信道估计和MUD方法。信道估计MSE和BER性能方面的结果证明了这种联合方案的有效性。

著录项

  • 作者

    Yang, Bin.;

  • 作者单位

    Carleton University (Canada).;

  • 授予单位 Carleton University (Canada).;
  • 学科 Engineering Electronics and Electrical.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 224 p.
  • 总页数 224
  • 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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