宽带相关信道下的MIMO-DFE自适应空时接收机

设计了基于RLS算法的宽带自适应判决反馈MIMO-DFE空时接收机,由于这种接收机不需要信道识别,从而降低了接收机的复杂度。通过蒙特卡罗仿真评估了接收机在宽带相关信道下的误码率性能。仿真结果表明,在宽带相关信道下,相关性越大,接收机的性能下降越严重。在相关系数为0.3、误码率为10~(-3)数量级时,由于信道相关使信噪比损失2dB左右。     

多址通信

Y99-61821-1089 2002543出现衰落时 CDMA 的多信道干扰消除=Multichanndinterference cancellation for CDMA in the presence offading[会,英]/Ghazi-Moghadam,V.& Kaveh,M.//1998 32nd Asilomar Conference.Vol.2.—1089～1093(PC)提出了把干扰消除接收机作为 CDMA 系统用低复杂性接收机的建议。介绍了采用自适应天线阵的连续干扰消除接收机。提出两种方案,以使天线阵在各级适应用户之一和消除来自正进入下一级信号的用户。比较了两种方案在多径衰落环境中的性能,并说明了比单码元干扰消除接收机的改进。参7Y99-61821-1199 2002544卷积编码自适应 CDMA 接收机结构=A convolutional-ly-codeA adaptive CDMA receiver architecture[会,英]/     

宽带自适应MIMO-DFE空时接收机

设计了频率选择信道基于RLS算法的自适应判决反馈均衡MIMO-DFE空时接收机,由于这种接收机不需要信道识别,从而降低了接收机的复杂度。通过蒙特卡罗仿真评估了接收机在频率选择信道下的误符号率性能。仿真结果表明,在不加信道编码的情况下,该接收机在信噪比为 14dB时误符号率达到 10-3以下。     

异步多径条件下空时CDMA多用户检测

本文利用最小均方误差准则,推导了异步多径条件下空时CDMA多用户检测算法,分析了多用户检测与单用户检测关系,提出空时CDMA多用户检测接收机结构。基于SAGE迭代算法进行空时多用户检测,并利用CDMA信号的有限字符特性和上行信道的导频信息对SAGE算法提出改进。仿真结果说明了本文提出的空时CDMA多用户检测算法性能。     

WCDMA系统中导频符号辅助的空时二维RAKE接收机

针对WCDMA上行链路的时分导频和复扩频方式的特点 ,提出了一种适用于WCDMA系统的线性自适应空时二维RAKE接收机 .利用导频符号进行信道估计 ,并作为空间波束成型器的参考信号 .理论分析和在多用户时变频率选择性衰落信道下的仿真研究表明 ,对导频信号的充分利用可以降低空时二维接收机的实现复杂度 ,所提的接收机能明显提高接收机的输出信干噪比 ,降低误码率     

接收机

Y2000-62329-239 0016561多径信道中异步 CDMA 系统用的多址联接干扰消除器增强 Rake 接收机=Multiple access interference(MAI)canceller enhanced Rake receiver for asyn-chronous CDMA system in multipath channels[会,英]/Chitamu,P.J.//1999 Africon,Vol.1.—239～244(PC)Y2000-62335-583 0016562采用自适应天线阵的上行链路 CDMA QPSK 接收机用的时空抵消检测器=Space—time cancellation detec-tor for up-link CDMA QPSK receivers with adaptiveantenna arrays[会,英]/Morosi,S.& Re,E.D.//     

CDMA系统中2-D RAKE接收机的性能研究

CDMA系统中,信号在无线信道中传输,由于多用户同时同频传输和多径衰落的存在,导致多址干扰(MAD和符号间干扰(ISI),使系统接收机的性能下降.空时接收机(2-D RAKE)能够有效地抑制MAI和对抗多径衰落,这里介绍了几种接收机的工作特点,并对各种空时接收机进行了详细的分析和比较.     

多径信道下一种线性空时多用户检测方法

给出了用于DS/CDMA系统的线性空时多用户接收机的数学模型,分析了在多用户空时接收机中空域处理和时域匹配滤波的作用,引入SOR算法,并将其改进应用到多径信道下的线性空时多用户检测中。通过迭代避免了直接求逆运算,显著降低了运算复杂度。仿真表明:线性空时多用户接收机能够明显提高接收机性能,并且随着接收机天线数的增加性能明显提高。     

阵列天线波束成形技术在宽带CDMA下行链路中的应用

本文利用自适应天线阵列上行链路信号到达角估计信息,并结合导频辅助下行链路信道矩阵估计值,在前人提出的具有反馈特性的自适应发送阵列原理基础上,提出一种简单可行的宽带CDMA下行链路天线阵列波束成形权重计算方法,并进一步分析了到达角估计误差和信道信息反馈时延对权重计算的影响,最后给出系统误码率性能的计算机仿真结果。     

STBC MIMO CDMA系统CMVDR接收机研究

提出了STBC MIMO CDMA系统中一种新的基于多用户ML估计的带制约的最小方差无失真响应(CMVDR)接收机，能有效抑制多址干扰(MAD和符号间干扰(ISI)。给出了多用户、多径的STBC MIMO CDMA系统信道模型及ML参数估计，并给出了分部加权和整体加权两种CMVDR接收机，本接收机也适用于SIMO CDMA系统。进行了系统模拟，并对分部加权和整体加权两种CMVDR接收机的性能以及自适应CMMSE接收机的性能进行了比较分析。     

Adaptive multichannel lattice-escalator filter structure: anapplication to generalized sidelobe canceler

An adaptive digital filter structure which can be used in multichannel noise-canceling applications is described. The proposed structure is obtained by creating a hybrid from the lattice and the escalator (Gram-Schmidt) structures, with the coefficients being updated using the least mean square (LMS) algorithm. As an application, the proposed adaptive multichannel digital filter is applied to implement an adaptive generalized sidelobe canceler     

Damping of Torsional Vibrations in Two-Mass System Using Adaptive Sliding Neuro-Fuzzy Approach

In this paper, a new robust control system with the adaptive sliding neuro-fuzzy speed controller for the drive system with the flexible joint is proposed. A model reference adaptive control structure (MRAC) is used in this drive system. The torsional vibrations are successfully suppressed in the control structure with only one basic feedback from the motor speed. The damping ability of the proposed system has been confirmed for a wide range of the system parameters and compared with the other control concepts, like the adaptive Pi-type neuro-fuzzy controller and the classical cascade PI structure.     

A Modular Design of LMS Adaptive Filter Based on FPGA

针对LMS自适应滤波器在FPGA上实现结构灵活性的问题,提出了一种模块化设计方法。根据LMS算法结构特点,结合FPGA硬件语言特点进行模块化设计,分别阐述了各模块设计结构,对模块进行并行调用与综合。对模块化设计的自适应滤波器与纯串行及纯并行设计的自适应滤波器所占用的资源以及处理速率进行比较,8个并行模块结构比全串行结构处理速率快了近7.6倍,硬件资源占用比全并行结构减少了近50%;结果说明模块化LMS自适应滤波器设计具有更加灵活的结构特点。     

New structures for adaptive filtering in subbands with critical sampling

Some properties of an adaptive filtering structure that employs an analysis filterbank to decompose the input signal and sparse adaptive filters in the subbands are investigated in this paper. The necessary conditions on the filterbank and on the structure parameters for exact modeling of an arbitrary linear system with finite impulse response (FIR) are derived. Then, based on the results obtained for the sparse subfilter structure, a new family of adaptive structures with critical sampling of the subband signals, which can also yield exact modeling, is obtained. Two adaptation algorithms based on the normalized LMS algorithm are derived for the new subband structures with critical sampling. A convergence analysis, as well as a computational complexity analysis, of the proposed adaptive structures are presented. The convergence behavior of the proposed adaptive structures is verified by computer simulations and compared with the behavior of previously proposed algorithms.     

标准低密度奇偶校验码译码算法中量化结构

DVB-S2标准低密度奇偶校验码(LDPC)译码器在深空通信中面临着低复杂度、高灵活性及普适性方面的迫切需求。通过对LDPC译码算法中量化结构的研究,提出一种动态自适应量化结构的设计方法。该方法在常规均匀硬件量化的基础上,提出了修正化Min-Sum译码算法中的数据信息初始化及迭代译码的动态自适应量化结构,解决了DVB-S2标准LDPC码译码时存在的校验节点运算与变量节点运算之间的复杂度不平衡的问题,并由此提高了译码器的译码性能。实验证明,以DVB-S2标准LDPC码中码长为16 200,码率为1/2的为例,提供动态自适应量化结构与常规的均匀量化结构相比,节省硬件资源为4%。此外,动态自适应量化结构支持动态可配置功能,保证了DVB-S2标准LDPC译码器的灵活性及普适性。     

液压伺服系统自适应模糊变结构控制

结合变结构控制、自适应控制和模糊技术等特点,提出一种自适应模糊变结构控制方法.首先,设计一个带积分开关平面函数的变结构控制器,并构造一个二维模糊边界层宽度调节器以削弱抖振.其次,基于Lyapunov稳定性理论,引入一自适应算法,自适应调节变结构控制参数.应用于液压伺服系统的控制实验结果表明,所提出的控制方法能削弱抖振,改善液压伺服系统稳态控制精度,具有较强的鲁棒自适应综合性能.     

An Adaptive MMOE-PIC Detector for Asynchronous DS-CDMA Communications

We propose a modified linear parallel interference cancelation (PIC) structure using the adaptive minimum mean output-energy (MMOE) algorithm for direct-sequence code-division multiple-access (DS-CDMA) systems. The complexity of the proposed receiver structure is shown to be linear in the number of users and hence, lower complexity than the centralized minimum mean-squared error (MMSE) multiuser detector. It is demonstrated that the proposed receiver structure can significantly reduce the long training period required by the standard adaptive MMOE receiver in near-far environments. Both numerical and theoretical results show that the proposed receiver performs close to the optimum MMSE receiver whereas the conventional adaptive MMOE detector suffers from high BER’s due to the imperfect filter coefficients. Also our results show a three fold increase in the number of users when the MMOE-PIC is used relative to the conventional MMOE receiver. Furthermore, the transient behavior of the proposed MMOE-PIC receiver due to abrupt changes in the interference level is examined. It is shown that the proposed adaptive receiver offers much faster self recovery, with less signal-to-interference ratio (SIR) degradation, than the standard MMOE in sever near-far scenarios.     

Control of the Drive System With Stiff and Elastic Couplings Using Adaptive Neuro-Fuzzy Approach

In the paper a robust control system with the fuzzy-neural network is proposed. A model reference adaptive control system is applied to the one- and two-mass systems. Different aspects of application of the examined control structure are discussed. The influence of the number of neuro-fuzzy controller (NFC) rules to the drive system performance is shown. The impact of the electromagnetic torque limit to the adaptive structure stability is discussed. Further, the comparison of the dynamical characteristics of the different NFC structures is done. The control structure with constant and changeable parameters of the adaptive rule is also examined. The torsional vibration suppression in the two-mass system is obtained in the developed adaptive structure with only one basic feedback from the motor speed     

A system identification algorithm using orthogonal functions

An adaptive filter (ADF) structure is proposed for applications in which large-order ADFs are required. It is based on modeling the impulse response of the system to be identified as a linear combination of a set of discrete Legendre orthogonal functions. The proposed adaptive filter structure has desirable stability features and a unimodal mean-square error surface as well as a modular structure that permits an easy increase of the filter order without changing the previous stages. Computer simulations in which the proposed structure is used to identify actual acoustic echo path impulse responses show that the Legendre ADF has better convergence performance than the transversal ADF when identifying systems with long impulse response     

一种改进的用于Hammerstein预失真器的自适应结构

针对目前的自适应结构不利于Hammerstein预失真器进行参数更新,尤其是不利于线性子系统参数更新的问题,该文在间接学习结构的基础上提出了一种改进的自适应预失真结构。应用该结构能够得到Hammer-stein预失真器中待识别线性子系统的误差,使得高效的最小二乘算法能够直接对其参数进行更新,进而提高了整个预失真器的线性化性能。仿真结果表明：应用文中自适应结构,Hammerstein预失真器可以高效地补偿带记忆效应功率放大器的非线性失真。