本文为波兰克拉科夫AGH科技大学（作者：Paweł Kułakowski）的博士论文，共133页。
众所周知，多输入多输出(MIMO)系统能够增加无线链路的吞吐量，并克服多径衰落的影响。然而，MIMO系统在无线网络标准中的集成是缓慢的，因为还有许多问题尚未解决。这篇博士论文涉及慢变化和快变化无线信道中的MIMO系统。首先，考虑MIMO系统的一般问题，讨论了多路复用增益和分集的概念、信道知识、编码技术、多用户接入和宽带传输。接下来，研究MIMO系统的信道特性，解决了多径传播、信道模型、无线信道变化和信道估计的问题。然后，作者对慢变、快变MIMO信道进行了研究。对以下内容进行建模并予以证明：
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通过选择合适的接入点位置和天线，可以显著提高室内MIMO系统慢变无线信道的数据吞吐量。 -
迭代信道估计（ICE）算法允许在不频繁传输训练序列的情况下降低快变无线信道中的误码率。
上述第一条是基于慢变MIMO信道的数值射线追踪计算的，它指出了接入点天线位置、间隔和特性如何影响系统吞吐量。第二条是基于快变信道的ICE算法，ICE算法能够在数据传输的同时进行信道估计。当应用ICE算法时，可以降低误码率——在某些情况下，误码率能够降低50倍以上。
Multiple-input multiple-output (MIMO)systems are well known as a technique which allows increasing the throughput ofa radio link and overcoming the effects of multipath fading. However, the integrationof MIMO systems into the standards of wireless networks is slow, as there arenumerous problems still unsolved. This PhD thesis deals with MIMO systems inslow and fast varying radio channels. First, the general issues of MIMO systemsare considered. Multiplexing gain and diversity concepts, channel knowledge,coding techniques as well as multiuser access and wideband transmission arediscussed. Next, the channel aspects of MIMO systems are investigated. Thephenomenon of multipath propagation, channel models, variations in the radiochannel and channel estimation are addressed. Then, the author’s research inthe area of slow and fast varying MIMO channels is presented. The followingtheses are formulated and proved:
- The throughput in slow varying radio channels of indoor MIMO systems can besignificantly increased when the locations and the antennas of the access pointare carefully chosen.
- Iterative Channel Estimation (ICE) algorithm allows decreasing the bit errorrate in fast varying radio channels without frequent transmissions of trainingsequences.
The first thesis is founded on thenumerical ray tracing calculations concerning slow varying MIMO channels. It isshown how the locations, the separations and the characteristics of the accesspoint antennas can affect the system throughput. The second thesis is based onthe proposed ICE algorithm for fast varying channels. ICE algorithm enables thechannel estimation simultaneously with the data transmission. When ICE isapplied, the bit error rate can be reduced – in some cases it is more than 50times.
1 MIMO系统基础
2 MIMO系统的无线信道
3 室内慢变无线信道的传输容量
4 快变无线信道估计
附录 平均误码率的标准差
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