本文为英国卡迪夫大学（作者：Li Zhang）的博士研究，共238页。

将多输入多输出（MIMO）技术与正交频分复用（OFDM）技术相结合，有可能为未来的宽带无线系统提供空中接口解决方案。MIMO-OFDM系统面临的一个主要挑战是多用户在同一带宽上传输引起的多址干扰（MAI）问题。因此，需要新的信号处理技术来减轻MAI，从而提高链路性能。本文介绍了空时分组码（STBCs）在多输入多输出系统中利用分集增益的背景，并介绍了OFDM技术。OFDM系统的链路性能对信道的时变特性也很敏感。因此，提出了迭代最小均方误差（MMSE）接收机来克服这种时变特性。

在同步上行链路传输的背景下，针对STBC MIMO-OFDM提出了一种新的两步硬判决干扰对消接收机，该接收机性能稳定，且复杂度相对较低。通过采用误差控制编码方法和迭代算法，接收机性能得到了进一步的改进。通过帧误码率仿真，给出了一种基于MMSE干扰抑制和纠错编码的软输出多用户检测器，使其性能显著提高。最后，基于turbo原理，结合多用户检测，设计了一种低复杂度的迭代干扰对消检测方案，以在软干扰对消线性MMSE算法的指数计算复杂度和迭代turbo处理方案的近容量性能之间提供良好的折衷。

The combination of multiple-input multiple-output (MIMO) technology and orthogonal frequency division multiplexing (OFDM) is likely to provide the air-interface solution for future broadband wireless systems. A major challenge for MIMO-OFDM systems is the problem of multi-access interference (MAI) induced by the presence of multiple users transmitting over the same bandwidth. Novel signal processing techniques are therefore required to mitigate MAI and thereby increase link performance. A background review of space-time block codes (STBCs) to leverage diversity gain in MIMO systems is provided together with an introduction to OFDM. The link performance of an OFDM system is also shown to be sensitive to time-variation of the channel. Iterative minimum mean square error (MMSE) receivers are therefore proposed to overcome such time-variation. In the context of synchronous uplink transmission, a new two-step hard- decision interference cancellation receiver for STBC MIMO-OFDM is shown to have robust performance and relatively low complexity. Further improvement is obtained through employing error control coding methods and iterative algorithms. A soft output multiuser detector based on MMSE interference suppression and error correction coding at the first stage is shown by frame error rate simulations to provide significant performance improvement over the classical linear scheme. Finally, building on the uturbo principle” , a low-complexity iterative interference cancellation and detection scheme is designed to provide a good compromise between the exponential computational complexity of the soft interference cancellation linear MMSE algorithm and the nearcapacity performance of a scheme which uses iterative turbo processing for soft interference suppression in combination with multiuser detection.

1 引言

2 项目背景回顾

3 MIMO-OFDM通信

4 用于STBC MIMO-OFDM系统的两步多用户检测方案

5 STBC MIMO-OFDM系统的迭代多用户检测

6 低复杂度迭代干扰消除与多用户检测

7 结论 

下载英文原文地址：

http://page2.dfpan.com/fs/4lc9j2f21c29d16b9b1/

更多精彩文章请关注微信号：