多径MIMO CDMA系统中改进的盲空时多用户检测算法  

An improved blind space-time multiuser detection algorithm for asynchronous MIMO CDMA system

作　　者：于文君[1] 何培宇[1] 黄如浩[1] 高勇[1] 

机构地区：[1]四川大学电子信息学院,成都610065

出　　处：《四川大学学报（自然科学版）》2011年第1期92-98,共7页Journal of Sichuan University(Natural Science Edition)

基　　金：通信抗干扰技术国家重点实验室资助项目(JG2007055)

摘　　要：针对多径衰落信道下发射分集采用Alamouti空时分组码的MIMO CDMA系统,提出了一种改进的基于子空间的盲MMSE空时多用户检测算法.结合目标用户特征波形先验知识和多径信道信息对信号子空间进行预处理,然后使用正交性能和稳态性能较好的NOOja算法跟踪信号子空间,并在跟踪初期对信号特征值矩阵进行处理,去除迭代带来的噪声.仿真结果表明这种算法能有效地抑制多径干扰和多址干扰,尤其在低信噪比、远近效应明显的恶劣环境下,有稳定良好的性能表现.An improved blind linear minimum-mean-square-error（MMSE） space-time multiuser detector （MUD）and its adaptive implementation based on a signal subspace tracking algorithm is presented for the asynchronous multiple input multiple output Direct Sequence Code Division Multiple Access （MIMO DS/CDMA ） communication system in fading multipath channels. The Alamouti space-time block coding （STBC） scheme is adopted to achieve the spatial diversity on transmit antennas. Some attempts are ex- ploited to improve the performance of the system. The signal subspace can be pretreated by modifying a rough estimated signal subspace with the prior knowledge of the desired user signature waveform and the available information of MIMO wireless channels. Then the proposed detector employs the normalized orthogonal Oja （NOOja） algorithm for subspace estimation, since it guarantees the better stability and orthogonality of the signal subspace in every iteration than other subspace tracking algorithms. The ei- genvalue matrix is dealt with to remove noise in initial stage of the adaptive process. The numerical sim- ulation results show that this algorithm is efficient to suppress multiple access interference （MAI） and combat the near-far effect. In particular, it has good tracking ability and steady-state performance in the low SNR and distinct near-far effect environment.

关 键 词：多输入多输出 盲多用户检测 修正信号子空间 空时分组码 NOOja 

分 类 号：TN914.5[电子电信—通信与信息系统]