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Signal-perturbation-free semi-blind channel estimation for MIMO-OFDM systems.

机译：MIMO-OFDM系统的无信号扰动半盲信道估计。

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摘要

Multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) has been considered as a strong candidate for the beyond 3G (B3G) wireless communication systems, due to its high data-rate wireless transmission performance. It is well known that the advantages promised by MIMO-OFDM systems rely on the precise knowledge of the channel state information (CSI). In real wireless environments, however, the channel condition is unknown. Therefore, channel estimation is of crucial importance in MIMO-OFDM systems.;In the first part of the dissertation, several nulling-based semi-blind approaches are presented for the estimation of time-domain MIMO-OFDM channels. By incorporating a blind constraint that is derived from MIMO linear prediction (LP) into a training-based least-square method, a semi-blind solution for the time-domain channel estimation is first obtained. It is revealed through a perturbation analysis that the semi-blind solution is not subject to signal perturbation and therefore is superior to pure blind estimation methods. The LP-based semi-blind method is then extended for the channel estimation of MIMO-OFDM systems with pulse-shaping. By exploiting the pulse-shaping filter in the transmitter and the matched filter in the receiver, a very efficient semi-blind approach is developed for the estimation of sampling duration based multipath channels. A frequency-domain correlation matrix estimation algorithm is also presented to facilitate the computation of time-domain second-order statistics required in the LP-based method. The nulling-based semi-blind estimation issue of sparse MIMO-OFDM channels is also addressed. By disclosing and using a relationship between the positions of the most significant taps (MST) of the sparse channel and the lags of nonzero correlation matrices of the received signal, a novel estimation approach consisting of the MST detection and the sparse channel estimation, both in a semi-blind fashion, is developed. An intensive simulation study of all the proposed nulling-based methods with comparison to some existing techniques is conducted, showing a significant superiority of the new methodologies.;The second part of the dissertation is dedicated to the development of two signal-perturbation-free (SPF) semi-blind channel estimation algorithms based on a novel transmit scheme that bears partial information of the second-order statistics of the transmitted signal to receiver. It is proved that the new transmit scheme can completely cancel the signal perturbation error in the noise-free case, thereby improving largely the estimation accuracy of correlation matrix for channel estimation in noisy conditions. It is also shown that the overhead caused by the transmission of the 8PF data is negligible as compared to that of regular pilot signals. By using the proposed transmit scheme, a whitening rotation (WR)-based algorithm is first developed for frequency-domain MIMO-OFDM channel estimation. It is shown through both theoretical analysis and simulation study that the new WR-based algorithm significantly outperforms the conventional WR-based method and the nulling-based semi-blind method. By using MIMO linear prediction, the new WR-based algorithm utilizing the 8PF transmit scheme is then extended for time-domain MIMO-OFDM channel estimation. Computer simulations show that the proposed signal-perturbation-free LP-based semi-blind solution performs much better than the LP semi-blind method without using the proposed transmit scheme, the LS method as well as the nulling-based semi-blind method in terms of the MSE of the channel estimate.;Semi-blind channel estimation as a combination of the training-based or pilot-assisted method and the pure blind approach is considered to be a feasible solution for practical wireless systems due to its better estimation accuracy as well as spectral efficiency. In this thesis, we address the semi-blind channel estimation issue of MIMO-OFDM systems with an objective to develop very efficient channel estimation approaches.
机译：由于其高数据速率无线传输性能，多输入多输出正交频分复用（MIMO-OFDM）被认为是超越3G（B3G）无线通信系统的强大候选者。众所周知，MIMO-OFDM系统所承诺的优点取决于对信道状态信息（CSI）的精确了解。但是，在实际的无线环境中，信道条件是未知的。因此，信道估计在MIMO-OFDM系统中至关重要。在本文的第一部分，提出了几种基于零位的半盲方法来估计时域MIMO-OFDM信道。通过将源自MIMO线性预测（LP）的盲约束合并到基于训练的最小二乘法中，首先获得了用于时域信道估计的半盲解决方案。通过微扰分析表明，半盲解不受信号微扰的影响，因此优于纯盲估计方法。然后，将基于LP的半盲方法扩展为具有脉冲整形功能的MIMO-OFDM系统的信道估计。通过利用发射机中的脉冲整形滤波器和接收机中的匹配滤波器，开发了一种非常有效的半盲方法，用于估计基于采样持续时间的多路径信道。还提出了一种频域相关矩阵估计算法，以简化基于LP的方法所需的时域二阶统计量的计算。还解决了稀疏MIMO-OFDM信道的基于零位的半盲估计问题。通过揭示和使用稀疏信道的最高有效抽头（MST）的位置与接收信号的非零相关矩阵的滞后之间的关系，一种新颖的估计方法包括MST检测和稀疏信道估计，两者研制出一种半盲时尚。与所有现有技术相比，对所有提议的基于零值的方法进行了深入的模拟研究，显示了新方法的显着优势。;论文的第二部分致力于开发两种无信号扰动的方法（ SPF）基于一种新颖的传输方案的半盲信道估计算法，该算法承载了向接收机传输的信号的二阶统计量的部分信息。实践证明，该新的传输方案可以在无噪声的情况下完全消除信号扰动误差，从而大大提高了噪声条件下信道估计相关矩阵的估计精度。还表明，与常规导频信号相比，由8PF数据传输引起的开销可以忽略不计。通过使用提出的传输方案，首先开发了基于白化旋转（WR）的算法用于频域MIMO-OFDM信道估计。通过理论分析和仿真研究表明，新的基于WR的算法明显优于传统的基于WR的方法和基于归零的半盲方法。通过使用MIMO线性预测，利用8PF传输方案的基于WR的新算法随后被扩展用于时域MIMO-OFDM信道估计。计算机仿真表明，在不使用建议的传输方案，LS方法以及基于零位的半盲方法的情况下，所提出的基于信号无扰动的基于LP的半盲方法的性能要比LP半盲法好得多。半盲信道估计是基于训练或导频辅助的方法与纯盲方法的组合，由于其更好的估计精度，被认为是实际无线系统的可行解决方案以及频谱效率。本文旨在解决MIMO-OFDM系统的半盲信道估计问题，以期开发出非常有效的信道估计方法。

著录项

  • 作者

    Wan, Feng.;

  • 作者单位

    Concordia University (Canada).;

  • 授予单位 Concordia University (Canada).;
  • 学科 Engineering Computer.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 236 p.
  • 总页数 236
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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