【作者】 兴旺；

【导师】 曾召华；

【作者基本信息】 西安科技大学 ， 通信与信息系统， 2011， 硕士

【摘要】 本文研究了MIMO系统信道间的空间相关性对信道容量的影响,分析了天线间距和角度扩展等参数与空间相关性大小的关系,而这些所得结论对MIMO技术在室内环境中更好的应用具有指导意义。本文还涉及了MIMO系统接收端检测算法的性能仿真分析,为进一步提出高效低复杂度的检测算法提供理论依据。首先,本文基于相关矩阵法建立了一种MIMO信道空间相关模型,该模型主要考虑了两种空间信道参数,一个是以角度功率谱来描述的角度扩展,另一个是天线间距。从仿真结果可以得出,在瑞利衰落信道下,天线之间的相关系数与天线间距、到达波的角度扩展有着直接的关联,一般地,天线间距越大,达波角度扩展越宽,则相关系数越小,反之则相关系数越大,而较大的空间相关性会引起信道容量的损失。其次,本文讨论了一种小尺度衰落的室内MIMO信道模型:直射路径与散射路径共存的莱斯衰落信道,通过仿真对该模型的性能进行了预测,分析了直射分量、散射分量、以及莱斯因子对信道容量的影响,得出在直射矩阵低秩的信道下,随着莱斯因子值的增大,MIMO系统的信道容量降低。最后,对MIMO系统中最具代表性的垂直分层空时编码系统进行了介绍,并仿真分析了该系统几种检测算法性能。在假设理想信道估计下,得出最大似然算法检测性能最优,但其算法复杂度比较高,很难在实际中应用;基于迫零、最小均方误差准则算法的复杂度比较低,但它们的检测性能却较差;而基于串行干扰消除思想的迫零、最小均方误差算法的性能和复杂度就比较适中,而且当收发天线数都为4时,这两种算法的性能都要好于收发天线数为2的情况。更多还原

【Abstract】 This paper studies on the spatial correlation between channel and channel capacity in MIMO wireless system, analyzes the relationship between spatial correlation and several parameters, such as angle spread, antenna spacing. And these conclusions have guiding significance for better application of MIMO technology in indoor environment. This paper has also covered the performance simulation analysis of the receiver detection algorithm in MIMO system, this provides theoretical basis to further put forward the high efficient and low complexity algorithm.First, this paper establishes a kind of MIMO spatial correlation channel model based on correlation matrix method. The model considers the two main space channel parameters, one is angle spread (AS) that is described with power azimuth spectrum (PAS), the other is antenna spacing. From the simulation results can conclude, under Rayleigh fading channel, the correlation coefficient between antennas is directly related to antenna spacing and angle spread. Generally, the greater angle spread and antenna spacing, the smaller correlation coefficient, in contrast, the greater correlation coefficient, and the larger spatial correlativity can cause channel capacity loss.Secondly, the paper discusses a small scale decline indoor MIMO channel models: Rice fading channel, which includes LOS (line-of-sight) and NLOS (non line-of-sight) propagation environment. Through the simulation predicts the performance of the model, and analyzes the direct component, scattering component, and rice factors on the influence of channel capacity. With the increase of rice factor value, channel capacity of MIMO system reduces under low-rank channel matrix of direct component.Finally, V-BLAST (Vertical Bell Laboratories Layered Space-Time coding) system is introduced, which is the most representative in MIMO system, and this paper analyzes several detection algorithm performance by Matlab simulation. Assuming that under ideal channel estimation, Maximum likelihood (ML) algorithm has optimal detection performance, but it also has high algorithm complexity, so it is difficult for the application in practice. Although algorithm complexity based on zero forcing (ZF) and minimum mean square error (MMSE) rule is lower, but their detection performance is poor. And performance and complexity of detection algorithm based on serial interference cancellation (SIC) thought are moderate. When the number of sending and receiving antenna is four, the performance of this algorithm is better than the number of sending and receiving antenna is two.更多还原