The MultiCarrier Code Division Multiple Access (MC-CDMA) scheme is promising for relieving capacity limit problems of Direct Sequence (DS-) CDMA systems due to serious InterChip Interference (ICI) and MultiUser Interf...The MultiCarrier Code Division Multiple Access (MC-CDMA) scheme is promising for relieving capacity limit problems of Direct Sequence (DS-) CDMA systems due to serious InterChip Interference (ICI) and MultiUser Interference (MUI) in high-data-rate wireless communication systems. In this paper, the Uniform Linear Array (ULA) is applied to the base station of macrocellular MC-CDMA systems in a frequency-selective fading channel environment. A joint space-frequency multiuser symbol sequence detector is developed for all active users within one macrocell without space-frequency channel estimation. Simultaneously, Directions-Of-Arrivals (DOAs) of all active users can also be estimated. By dividing the ULA into two identical overlapping subarrays, a specific auxiliary matrix is constructed, which includes both symbol sequence and DOA information of all active users. Then, based on the subspace method, performing the eigen decomposition on such auxiliary matrix, the closed-form solution of symbol sequences and DOAs for all active users can be obtained. In comparison with schemes based on channel estimation, our algorithm need not explicitly estimate the space-frequency channel for each active user,so it has lower computation complexity. Extensive computer simulations demonstrate the overall performance of this novel scheme.展开更多
针对基于互质阵列波达方向(direction of arrival, DOA)估计方法对连续虚拟阵元得到的样本协方差矩阵信息利用率不高的问题,提出一种基于互质阵列的协方差矩阵重构算法。该算法利用最大连续虚拟均匀线阵协方差矩阵的每一行元素进行Toepl...针对基于互质阵列波达方向(direction of arrival, DOA)估计方法对连续虚拟阵元得到的样本协方差矩阵信息利用率不高的问题,提出一种基于互质阵列的协方差矩阵重构算法。该算法利用最大连续虚拟均匀线阵协方差矩阵的每一行元素进行Toeplitz矩阵重构,再对这些矩阵加权求和获得新的满秩协方差矩阵,提高对接收数据的利用率并消除噪声贡献对DOA估计结果的影响。理论分析和仿真结果表明,该算法能实现欠定DOA估计,在低信噪比、小快拍数、入射角度间隔小条件下有良好的角度估计精度。展开更多
A novel method to estimate DOA of coherent signals impinging on a uniform circular array( UCA) is presented in this paper. A virtual uniform linear array (VULA) is first derived by using spatial DFT technique, transfo...A novel method to estimate DOA of coherent signals impinging on a uniform circular array( UCA) is presented in this paper. A virtual uniform linear array (VULA) is first derived by using spatial DFT technique, transforming the UCA from element space to phase mode space to obtain the properties of ordinary ULA, and then the well known spatial smoothing technique is applied to the VULA so that the lost rank of covariance matrix due to signal coherence can be retrieved. This method makes it feasible to use the simple MUSIC algorithm to estimate DOA of coherent signals impinging on a UCA without heavy computation burden. Simulation results strongly verify the effectiveness of the algorithm.展开更多
传统的阵列波束展宽技术需要对阵元施加复加权操作,实现起来相对复杂。提出了一种基于多种群遗传算法(Multiple Population Genetic Algorithm,MPGA)的唯相加权阵列波束展宽技术,并针对均匀直线阵列和扇形圆环阵列,结合其数学模型,分别...传统的阵列波束展宽技术需要对阵元施加复加权操作,实现起来相对复杂。提出了一种基于多种群遗传算法(Multiple Population Genetic Algorithm,MPGA)的唯相加权阵列波束展宽技术,并针对均匀直线阵列和扇形圆环阵列,结合其数学模型,分别设计出适配的适应度函数,通过MPGA对阵元内各个阵元的附加相位进行优化,经仿真实现了阵列波束展宽。结果表明,该方法可以在考虑天线阵列的副瓣电平及天线效率的同时,设计实现更宽的阵列波束,且收敛速度较快、稳健性较好,充分显示了MPGA在天线阵列设计中较好的应用前景。展开更多
以均匀直线阵和四阶累积量为基础,提出了一种新的空间特征盲估计算法。该算法首先利用阵列输出四阶累积量构造了一种空间特征矩阵,对其作特征分解可以得到各用户的空间特征估计。然后,在空间特征估计基础上,结合前向/共轭后向空间平滑...以均匀直线阵和四阶累积量为基础,提出了一种新的空间特征盲估计算法。该算法首先利用阵列输出四阶累积量构造了一种空间特征矩阵,对其作特征分解可以得到各用户的空间特征估计。然后,在空间特征估计基础上,结合前向/共轭后向空间平滑技术进行了多径波达方向(Direction of Arrival,DOA)估计。该方法突破了传统MUSIC、ESPRIT等算法的局限,可以利用M阵元估计2M2/3个DOA,且各DOA与信源自动配对。该算法不依赖于信号具体特征,适用于任意加性高斯噪声(如有色噪声)环境。理论分析和仿真结果说明了算法的有效性和鲁棒性。展开更多
基金Partially supported by the National Natural Science Foundation(No.69872029)and the Research Fund for Doctoral Program of Higher Education(No.19990690808)of China
文摘The MultiCarrier Code Division Multiple Access (MC-CDMA) scheme is promising for relieving capacity limit problems of Direct Sequence (DS-) CDMA systems due to serious InterChip Interference (ICI) and MultiUser Interference (MUI) in high-data-rate wireless communication systems. In this paper, the Uniform Linear Array (ULA) is applied to the base station of macrocellular MC-CDMA systems in a frequency-selective fading channel environment. A joint space-frequency multiuser symbol sequence detector is developed for all active users within one macrocell without space-frequency channel estimation. Simultaneously, Directions-Of-Arrivals (DOAs) of all active users can also be estimated. By dividing the ULA into two identical overlapping subarrays, a specific auxiliary matrix is constructed, which includes both symbol sequence and DOA information of all active users. Then, based on the subspace method, performing the eigen decomposition on such auxiliary matrix, the closed-form solution of symbol sequences and DOAs for all active users can be obtained. In comparison with schemes based on channel estimation, our algorithm need not explicitly estimate the space-frequency channel for each active user,so it has lower computation complexity. Extensive computer simulations demonstrate the overall performance of this novel scheme.
文摘针对基于互质阵列波达方向(direction of arrival, DOA)估计方法对连续虚拟阵元得到的样本协方差矩阵信息利用率不高的问题,提出一种基于互质阵列的协方差矩阵重构算法。该算法利用最大连续虚拟均匀线阵协方差矩阵的每一行元素进行Toeplitz矩阵重构,再对这些矩阵加权求和获得新的满秩协方差矩阵,提高对接收数据的利用率并消除噪声贡献对DOA估计结果的影响。理论分析和仿真结果表明,该算法能实现欠定DOA估计,在低信噪比、小快拍数、入射角度间隔小条件下有良好的角度估计精度。
文摘A novel method to estimate DOA of coherent signals impinging on a uniform circular array( UCA) is presented in this paper. A virtual uniform linear array (VULA) is first derived by using spatial DFT technique, transforming the UCA from element space to phase mode space to obtain the properties of ordinary ULA, and then the well known spatial smoothing technique is applied to the VULA so that the lost rank of covariance matrix due to signal coherence can be retrieved. This method makes it feasible to use the simple MUSIC algorithm to estimate DOA of coherent signals impinging on a UCA without heavy computation burden. Simulation results strongly verify the effectiveness of the algorithm.
文摘针对传统奈奎斯特采样会产生庞大的数据量以及现有的阵列压缩采样系统存在结构复杂、重构运算量大等问题,本文提出了一种基于均匀线型阵列的改进型调制宽带转换器(Modulated Wideband Converter,MWC)的阵列接收系统,无需重构即可直接对接收信号的压缩采样数据进行载频与波达方向(Direction Of Arrival,DOA)估计.所提系统在MWC测频支路中采用周期性循环移位伪随机序列作为混频函数以求得子带索引估计,采用基于快速傅里叶变换(Fast Fourier Transform,FFT)谱线插值法进行基带频率估计,且将MWC测向分支中混频函数设置为相同的伪随机序列,便可直接利用高分辨率的多重信号分类(MUltiple SIgnal Classification,MUSIC)算法对组合压缩采样数据完成DOA估计.实验仿真结果证明了所提系统能较好地从压缩采样数据中完成对目标的载频与DOA参数估计.
文摘传统的阵列波束展宽技术需要对阵元施加复加权操作,实现起来相对复杂。提出了一种基于多种群遗传算法(Multiple Population Genetic Algorithm,MPGA)的唯相加权阵列波束展宽技术,并针对均匀直线阵列和扇形圆环阵列,结合其数学模型,分别设计出适配的适应度函数,通过MPGA对阵元内各个阵元的附加相位进行优化,经仿真实现了阵列波束展宽。结果表明,该方法可以在考虑天线阵列的副瓣电平及天线效率的同时,设计实现更宽的阵列波束,且收敛速度较快、稳健性较好,充分显示了MPGA在天线阵列设计中较好的应用前景。
文摘以均匀直线阵和四阶累积量为基础,提出了一种新的空间特征盲估计算法。该算法首先利用阵列输出四阶累积量构造了一种空间特征矩阵,对其作特征分解可以得到各用户的空间特征估计。然后,在空间特征估计基础上,结合前向/共轭后向空间平滑技术进行了多径波达方向(Direction of Arrival,DOA)估计。该方法突破了传统MUSIC、ESPRIT等算法的局限,可以利用M阵元估计2M2/3个DOA,且各DOA与信源自动配对。该算法不依赖于信号具体特征,适用于任意加性高斯噪声(如有色噪声)环境。理论分析和仿真结果说明了算法的有效性和鲁棒性。
