【作者】 王鹏；

【导师】 冯正和；

【作者基本信息】 清华大学 ， 电子科学与技术， 2010， 博士

【摘要】 有限的频谱资源与日益增长的带宽需求是制约未来通信系统中各种新兴宽带技术普及的主要瓶颈。如何充分利用有限的频谱资源,提高频谱利用率,成为解决这一矛盾的关键问题。多输入多输出(MIMO)技术由于能够充分利用传播信道中的空间自由度而大幅度的提高系统容量和频谱利用率,因而被认为是未来通信系统中的关键技术。室内环境中的多径资源比其他环境要丰富的多,这成为MIMO技术在室内环境中应用的重要基础。采用多极化天线的MIMO系统有效提高了系统的紧凑性从而满足了室内环境对于MIMO设备体积的苛刻要求,因此成为MIMO技术中新兴的研究热点。为了进一步发掘多径环境中的多极化信道资源,本文重点研究了室内环境MIMO通信系统中信道的多极化传播特性。以极化多径信道的物理传播特性为主要研究对象,采用分离的方法精确测量实际场景中不同极化的多径信道,力图揭示MIMO信道传播的极化特征,为多极化MIMO系统的设计和应用提供有价值的参考。结合研究对象室内场景的特点,本文设计搭建了一套多极化宽带三维MIMO信道测量系统,按照测试需要设计制作了测量系统的多个扫描平台和天线单元等测试设备,并利用此系统对典型室内场景中的MIMO信道进行了大量的多极化三维测量。本文在已有的二维频域SAGE算法的基础上,推导了可用于发射端和接收端多极化联合估计的三维频域SAGE算法,并通过仿真和实际测量验证了该算法的有效性。本文通过对典型室内环境中实际信道测量结果的分析,证明了该类环境中不同极化方式信道的独立性和有效性。使用三维SAGE算法对实际测量结果进行了信道估计和参数提取,得到了对于室内多极化多径环境的信道建模和多极化天线阵列设计有价值的信道参数和优化设计方案。更多还原

【Abstract】 The conflict between the limited frequency spectrum resources and the increasing spectrum requirements is the main obstacle that restricts the popularization of the next generation wireless communication systems. Making the best of the limited frequency spectrum resources and improving the spectral efficiency are important method to resolve this problem. Multiple-Input–Multiple-Output (MIMO) is considerred as the key technology of the future communication systems for its ability of greatly improving the channel capacity and the spectral efficiency of the system by making good use of the spatial degree of freedom. Comparing with the outdoor applications, indoor wireless multichannel resource is more abundant, and this is the important basis for the application of MIMO technology in indoor environments. MIMO systems with multi-polarized antennas improve the compactness of the system to meet the demanding dimension requirements of the indoor environments for MIMO devices. Consequently, multi-polarization MIMO techniques become the focus of the wireless communication research.To further explore the multi-polarization resources in multi-path environments, this dissertation focuses on the channel propagation characteristics of multi-polarization in indoor MIMO communication systems. The main study object is the physical propagation characteristics of the multi-polarized mult-ipath channel. The multi-path channels of different polarizations in the actual scenes are accurately measured using the separated method, trying to reveal the propagation characteristics of the polarized MIMO channel, and providing valuable information for the designs and applications of the multi-polarization MIMO systems.To measure the channel characteristics in indoor scenes, a multi-polarized three-dimensional wideband MIMO channel measurement system is designed and established. Several scanning measurement platforms, antennas and other testing equipments are fabricated according to the requirements of the actural measurement. A large number of multi-polarized three-dimensional measurements on MIMO channels in typical indoor scenes are carried out using this measurement system. Based on the existing two-dimensional frequency domain Space-Alternating Generalized Expectation maximization (SAGE) algorithm, a three-dimensional frequency domain SAGE algorithm, which can be used for combined multi-polarization estimation of the transmitter and receiver, is derived and verified by actual simulations and measurements.The actual measurement results of MIMO channels in typical indoor environments show the independence and effectiveness of the channel with different polarization in this kind of environments. The three-dimensional SAGE algorithm is used in channel estimation and parameters extraction of the actual measurement results. Valuable channel parameters and optimized design plan for indoor multi-polarized multipath channel modeling and antenna arrays designing are summarized.更多还原