【作者】 刘婕；

【导师】 陈伟；

【作者基本信息】 武汉理工大学 ， 通信与信息系统， 2006， 硕士

【摘要】 新一代无线通信系统要求比现行蜂窝无线标准更高的通信质量和传输速率,采用常规发射分集或接收分集技术不足以解决新一代无线通信系统的大容量与高可靠性需求性问题。多入多出(MIMO)无线通信技术在无线链路两端均采用多天线接收与发射,提供了解决该问题的新途径;空时编码技术将信道编码技术与天线分集技术相结合,大幅度增加了无线通信系统的容量,提高了多径衰落信道的通信质量。 本文在已有的研究工作基础上,主要对无线MIMO系统的随机信道特性及信道容量,正交空时编码技术及改进四个方面涉及到的有关理论进行进一步研究,得出了几点新结论,并通过大量仿真加以验证,本文主要内容概括如下: (1)研究无线信道的特性,分析MIMO系统的传播环境,建立了用于第三代及多天线MIMO通信系统的随机信道模型,在已有空时信道模型的研究基础上,综合信道衰落系数的相关性,发射信号的离开角和扩展角,接收信号的功率水平分布和多普勒频移,给出随机信道仿真方法及随机信道模型仿真分析。 (2)对具有随机信道系数的快瑞利和块瑞利衰落信道、慢瑞利衰落信道进行容量分析,给出了相关MIMO系统容量仿真结果。 (3)正交空时分组编码是MIMO通信中的关键技术,能克服无线信道的多径衰落,它的优点是编译码简单且可得到最大分集增益。本文详细研究了正交空时编码基本原理、空时分组编码的正交设计及正交空时分组编码的编码译码过程,并给予相关仿真结果。 (4)提出了一种基于正交设计改进的空时编码。基于正交空时分组编码的详细研究,针对MIMO系统中的空时编码联合提高传输分集性能和传输复用性能的问题,在线性扩展空时码LDC的基础上提出正交线性扩展空时码OLDC,仿真结果表明OLDC码比传统的LDC码在误码性能、分集性能、复用性能等方面均有大幅度提高。更多还原

【Abstract】 The third generation wireless communication systems require higher communication quality and transmission rate than cellular wireless standard, and the traditional communication systems using single-antenna transmitting and receiving are confronted with a stiff challenge to achieve this target. MIMO methods make use of the radio link, which has provided a novel solution to this problem. The technique of space-time coding(STC) is mainly designed by combining the technique of channel coding and array diversity, hence increasing the capacity of wireless communication systems and improving communication quality of multipath fading channel.The dissertation has mainly made further research on the related theories about four main aspects: the characteristics of random channel in MIMO system, channel capacity, orthogonal space-time coding and improved coding method base on recent work and a few new conclusions were derived in the dissertation. Moreover, the important results were obtained by a number of computer simulations. The main contents of the dissertation are expressed as follows:(1) The charaderistics of wireless channel and trasmitting environment are studied in depth. On the basis of recent research on the theories of space-time model, a random channel model in 3G and multi-antenna MIMO system was built. According to correlation function of channel fading coefficient, the angle of departure of transmitting signal and its spread angle, power horizontal distribution and Doppler spectrum, the simulation method and simulation analysis of the random channel model are given.(2) It is specifically analyzed the capacity for rapid Raleigh fading channel, block Raleigh fading channel and slow Raleigh fading channel with random channel coefficient. The simulation results in MIMO system are also given.(3) Orthogonal Space-time Block Coding(OSTBC) is a key technology in MIMO communications. It has simply encode and decode algorithm and the most diversity. It is specifically studied Orthogonal Space-time Coding principle, theorthogonal design of Space-time Block Coding , encode&decode process of Orthogonal Space-time Block Coding and the related simulation results are given.(4) It is proposed an improved space-time coding based on orthogonal design. For the joint diversity and multiplexing performance, on the basis of the research on OSTBC, it is proposed Orthogonal Llinear Dispersion Space-time Code(OLDC) based on Linear Dispersion Space-time Code(LDC). Simulation results show that OLDC performance better than traditional LDC on BER, diversity and multiplexing capacity.更多还原