多天线下行链路中的空时传输技术研究

发布时间：2018-08-02 10:13

【摘要】：多输入多输出(Multiple Input Multiple Output,MIMO)技术可以为无线通信传输提供更高的系统容量和可靠性,是无线通信领域的重要研讨课题。空间分集(Spatial Diversity)、空间复用(Spatial Multiplexing)和空间调制(Spatial Modulation)等技术各有优势,适用于不同的传输环境。上述技术中,空间分集技术利用空间和时间维度联合编码发送一个数据流的多个副本,在接收端便可获得多条路径的增益,从而克服信道衰落的影响,提升系统的性能。空时编码技术作为最常见和最典型的空间分集技术已受到了广大学者的关注和研究。本文的研究基于下行多天线链路中的空时传输技术,进而将其考虑到分布式天线系统及空时编码辅助的空间调制技术,以捕获更高的数据传输率。论文的第一章回顾了无线通信的发展历程,下行MIMO常用的技术及空时编码技术的研究现状。论文的第二章介绍了MIMO中常见的三种传输技术:空时编码、空分复用和空间调制技术,并给出了这三种传输技术的系统模型及数学模型,分析了三种传输技术的优缺点,进而仿真比较了其性能。此外,第二章还介绍了不同发送天线数目的空时编码,并仿真其性能结果。论文的第三章首先介绍了快衰落分布式MIMO信道模型,给出了瑞利衰落信道及多普勒效应对传输的影响。第三章所研究的系统采用导频辅助调制的递归最小均方检测算法,故详细阐明了导频辅助原理及递归最小均方检测算法。进而,介绍了新型的分布式天线系统的信道模型,并将其与传统的集中式天线分布系统进行比较。仿真表明,分布式天线系统在小区内的性能更加稳定。论文的第四章作为本文的研究重点,对空时编码辅助的空间调制技术进行了探讨。针对天线维度较小的传输环境,为提升系统数据传输率,本文提出了一种新型的空时编码辅助的空间调制方案,所提方案采用天线选择技术并结合信道范数排序及信道间夹角最小的对天线进行分组,研究了3根发送天线时的传输系统,仿真表明本文提出的算法其性能较传统的采用天线选择技术的空间调制技术更优。对于天线维度较高的情形,基于传统的G4空时码,本文提出一种简化传输方案,此技术适用于高天线维度的传输情形,且译码复杂度非常低。对于此简化联合技术,本文对不同码率的正交/准正交空时编码分别进行了仿真,并对准正交空时编码传输的系统给出了一种改善方案。最后一章是全文总结,并介绍了未来可能的研究方向。
[Abstract]:Multi-input multiple-output (Multiple Input Multiple (MIMO) technology can provide higher system capacity and reliability for wireless communication transmission. It is an important research topic in the field of wireless communication. Spatial diversity (Spatial Diversity), techniques such as spatial multiplexing (Spatial Multiplexing) and spatial modulation (Spatial Modulation) have their respective advantages and are suitable for different transmission environments. In the above techniques, spatial diversity uses spatial and temporal dimensions to jointly encode multiple copies of a data stream and gain multiple paths at the receiving end, which overcomes the influence of channel fading and improves the performance of the system. As the most common and typical spatial diversity technology, space-time coding has been paid attention and studied by many scholars. The research of this paper is based on the space-time transmission technology in the downlink multi-antenna link, and then takes it into account the distributed antenna system and space-time coding assisted spatial modulation technology to capture higher data transmission rate. The first chapter reviews the development of wireless communication, the common technologies of downlink MIMO and the research status of space-time coding technology. The second chapter introduces three common transmission technologies in MIMO: space-time coding, space-division multiplexing and spatial modulation, and gives the system model and mathematical model of these three transmission technologies, and analyzes the advantages and disadvantages of the three transmission technologies. Then its performance is simulated and compared. In addition, the second chapter introduces the space-time coding with different number of transmit antennas, and simulates its performance. In the third chapter, the fast fading distributed MIMO channel model is introduced, and the influence of Rayleigh fading channel and Doppler effect on transmission is given. In the third chapter, the system adopts the pilot aided modulation recursive least mean square detection algorithm, so the pilot auxiliary principle and the recursive least mean square detection algorithm are expounded in detail. Furthermore, the channel model of a new distributed antenna system is introduced and compared with the traditional centralized antenna distributed system. Simulation results show that the performance of the distributed antenna system in the cell is more stable. In the fourth chapter, the space-time coding-assisted spatial modulation technology is discussed. In order to improve the data transmission rate of the system, a new space-time coding assisted spatial modulation scheme is proposed for the transmission environment with small antenna dimension. Using antenna selection technique and combining channel norm sort and minimum channel angle to group the antenna, the transmission system with three transmitting antennas is studied. Simulation results show that the proposed algorithm has better performance than the traditional spatial modulation technique using antenna selection technique. In the case of high antenna dimension, based on the traditional G4 space-time code, this paper proposes a simplified transmission scheme, which is suitable for the transmission of high antenna dimension, and the decoding complexity is very low. For this simplified joint technique, the orthogonal / quasi-orthogonal space-time codes with different bit rates are simulated, and an improved scheme for orthogonal space-time coding transmission systems is presented. The last chapter is a summary of the full text, and introduces the possible research direction in the future.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN919.3

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