多径异步LSC-DS-CDMA信号伪码估计  

Estimation of PN code of multipath asynchronous LSC-DS-CDMA signals

作　　者：潘微宇 赵知劲[1,2] PAN Wei-yu;ZHAO Zhi-jin(School of Communication Engineering,Hangzhou Dianzi University,Hangzhou 310018,China;State Key Lab of Information Control Technology in Communication System,No.36 Research Institute,China Electronic Technology Corporation,Jiaxing 314001,China)

机构地区：[1]杭州电子科技大学通信工程学院,浙江杭州310018 [2]中国电子科技集团第36研究所通信系统信息控制技术国家级重点实验室,浙江嘉兴314001

出　　处：《计算机工程与设计》2023年第1期52-58,共7页Computer Engineering and Design

基　　金：国家自然科学基金项目(61571172、U19B2016)。

摘　　要：针对多径环境下异步长短码直扩码分多址信号(long and short code direct sequence code division multiple access,LSC-DS-CDMA)伪码估计难的问题,提出一种基于张量分解和联合估计的伪码估计方法,采用重叠窗对接收信号进行分段并构建张量模型。为改善传统线性步长搜索算法结合梯度下降的方法分解因子矩阵收敛较慢的问题,提出改进的线性步长搜索算法,结合使用动量梯度下降法对各子张量进行Tucker分解得到各因子矩阵,所需的迭代次数大大减少;利用接收增益矩阵和移位相乘解决复合码的排序模糊和幅度模糊问题;利用最大似然准则联合估计复合码和多径信道后,使用梅西算法和相关运算估计每个用户的长码和短码。仿真结果表明,该方法能够有效估计多径异步LSC-DS-CDMA信号的伪码。Aiming at the problem that it is difficult to estimate the PN code of asynchronous LSC-DS-CDMA signal in multipath environment,a PN code estimation method based on tensor decomposition and joint estimation was proposed.The received signal was segmented by overlapping window and a third-order tensor model was constructed.To solve the problem that the traditional linear step search algorithm combined with gradient descent has slow convergence in factoring factor matrix,an improved linear step search algorithm was proposed,and the dynamic gradient descent method was used to implement Tucker decomposition of each sub tensor to get each factor matrix,the number of iterations was greatly reduced.The order ambiguity and amplitude ambiguity of composite codes were solved using the receiving gain matrix and shift multiplication.The maximum likelihood criterion was used to jointly estimate the composite code and the multipath channel,and the Massey algorithm and correlation operation were used to estimate the long code and the short code of each user.Simulation results show that the proposed method can effectively estimate the long code and short code of multipath asynchronous LSC-DS-CDMA signals.

关 键 词：张量分解 多径环境 长短码直扩码分多址 动量梯度下降法 步长搜索 最大似然准则 梅西算法 

分 类 号：TN914.42[电子电信—通信与信息系统]