【作者】 龚星宇；

【导师】 李国民；

【作者基本信息】 西安科技大学 ， 通信与信息系统， 2008， 硕士

【摘要】 直接序列扩频——码分多址(DS-CDMA)技术是目前应用在CDMA移动通信系统中最广泛的一种方式,它的性能主要受到多用户干扰和远近效应的影响。多用户检测技术是克服多用户干扰的关键技术。通过对现有多用户检测技术的研究分析,认为空域滤波与多用户检测技术相结合即空时联合检测技术是克服多用户干扰的有效方法。这种方法用空域滤波消除空间不同方向的多用户干扰,再用时域多用户检测技术来消除波束方向内的多用户干扰。首先,对空域滤波技术进行了研究分析。特别是在对波达方向估计的MUSIC方法进行了仿真研究的基础上,从阵列输出协方差矩阵入手,使噪声子空间经过处理后能够与方向矢量充分正交,从而解决原始MUSIC算法的不足,正确的估计出相关、相干或者是空间位置上很近的波达角度。接着比较了MUSIC及其改进方法的性能,以得到波达方向估计的有效方法。其次,研究了空时二维处理技术。通过对空域MMSE滤波器与解相关多用户检测器相结合以及空域MLSE滤波器与判决反馈检测器相结合的多用户检测技术的仿真分析,所得到的结果可以表明,与单一的时域多用户检测技术相比,空时结合多用户检测技术可以有效的提高系统的检测性能。更多还原

【Abstract】 At present, Direct Sequence-Code Division Multiple Access(DS-CDMA) technology is a way that widely using in the CDMA mobile communication system. Its performance is confined by two factors, one is the multiple access interference ( MAI ) , another is the near-far problem. And the multiuser detection technology is a key technology to overcome the multiple access interference ( MAI ).By research and analysis on the existence multiuser detection technology, the combination of the spatial filtering and the multiuser detection technology, also namely the combinative space-time multiuser detection technology, which is an effective way to solve the problem of the multiple access interference(MAI). This way uses spatial filtering to eliminate the multiple access interference(MAI) from different space directions, then it uses the time domain multiuser detection technology to eliminate the multiple access interference(MAI) from beam directions.At first, the paper makes research and analysis on spatial filtering technology. Especially on the ground of simulation research of the DOA estimating MUSIC method, the paper starts with the array covariance matrix, that makes the noise subspace algorithm be fully orthogonal with direction vector after preprocessing. With the result, the original MUSIC algorithm’s shortcomings can be resolved, and correlation、coherent or closed Space position Angle of Arrival is correctly estimated. Following, the performances of the MUSIC algorithm and the improved MUSIC algorithm are compared, that is for gainning an effective way of the DOA direction estimate.Secondly, the paper makes research on two-dimensional space-time processing technology. By simulation and analysis on the combination of the Spatial MMSE Filter and the Decorrelation Multiuser Detector, and the combination of the Spatial MLSE Filter and the Decision-Feedback Detector, the results show that the combinative space-time multiuser detection technology can effectively improve the detection performance by comparing with the time domain multiuser detection technology.更多还原