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在基于信道信息有限反馈的无线多入单出系统中,发射机可采用简单的波束成形技术实现发射分集增益和阵列增益。已有的相关研究大多包含块衰落信道、准确信道估计或无反馈延迟等理想假设。该文建立了更为实际的Jakes时变信道中存在信道估计误差和反馈延迟的系统模型,分析了方形和矩形正交幅度调制星座图的平均误码率。研究表明:误码率的理论分析和仿真结果完全相符;增加反馈比特数可提高阵列增益,但不能增加分集增益;在慢变信道中,波束成形要显著优于正交空时分组码;误码率受信道估计误差和反馈延迟影响,且对后者尤为敏感。 相似文献
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针对多输入多输出(Multiple Input Multiple Output, MIMO)系统中的空时分组码识别(Space-Time Block Code, STBC)问题,本文提出了一种利用卷积-循环神经网络的串行序列空时分组码识别方法。将一维接收信号的实部和虚部分离后输入网络,利用卷积神经网络(CNN)提取其空间特征,结合循环神经网络(RNN)提取其深层时序特征,提高网络的特征表达能力;网络训练过程采用反向传播方法,通过计算输出与目标值的误差,将误差反向传回网络中并更新权值,完成网络的训练过程;将测试集数据输入训练好的网络中,实现对空时分组码的识别和区分。该方法将深度学习算法运用到串行序列空时分组码识别当中,训练完的网络可直接对单接收天线下的空时分组码进行识别,不需要重复计算信号的统计特征,避免了人为设计特征参数和检测阈值。该方法不需要知道信道和噪声的先验信息,适用于电子侦查等非协作通信情况。仿真实验表明,该算法能够有效地对串行序列空时分组码进行识别,并且在低信噪比下有较好的识别性能。 相似文献
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文章提出了一种能减少解码端复杂度的新的解码方案。首先介绍了空时分组码的系统模型,然后介绍准正交空时分组码的系统模型和新的单符号解码算法,模拟仿真结果表明,该方案是一种简单有效的准正交空时分组码的解码方案。 相似文献
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提出了一种用于正交空时分组码(OSTBC:Orthogonal Space-Time Block Code)多发射天线多接收天线系统的盲自适应接收机.该方法主要利用了正交空时分组码的内在特性,给出了一个针对正交空时分组码多发射天线多接收天线系统的无约束代价函数,分析了该函数的全局最小值点.利用该无约束代价函数,通过投影逼近方法给出了递推最小二乘(RLS)自适应算法实现.仿真结果表明:该接收机可以很好的跟踪衰落信道的变化,在不利用导频信号的情况下很好的还原出原始的传输信号. 相似文献
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基于Alamouti提出的BPSK调制下空时分组码在Rayleigh衰落信道中的简单分集方案。推导出多发射和多接收天线系统中正交空时分组码在Nakagami衰落信道的BPSK调制下的比特差错率的最小距离球界,并推广到在高阶调制下衰落信道中系统符号差错率的性能。仿真分析和比较了空时分组码的多天线系统中发射和接收天线分集增益,以及信道相关参数的变化对系统误比特性能的影响。 相似文献
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采用准正交设计的空时分组码虽然可以达到速率为1,但是牺牲了部分分级增益。广义ABBA(GABBA,Generalized ABBA)空时分组码提出了一种改进型块状迭代准正交分组空时码(QOSTBC,Quasi-orthogonal Space-time Code)编码方式。此编码方式能提供全分集增益,并且满速率传输。克服原有正交分组空时码(OSTBC,Orthogonal Space-time Block Codes)在多天线(天线数大于2)、复信号时不能实现全速率传送的缺点。OFDM调制技术是抗多径效应的有效手段之一,两者相结合的MIMO-OFDM系统很好利用了时间、空间和频率三种分集,使系统达到很高的传输效率和频谱利用率。 相似文献
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Costas Laoudias Costas Psychalinos 《Analog Integrated Circuits and Signal Processing》2010,65(1):77-88
Novel Single Input Multiple Output (SIMO) and Multiple Input Single Output (MISO) current-mode universal biquad topologies
are introduced in this paper. The proposed topologies have been realized by employing low-voltage current mirrors as active
elements. As a result, an absence of resistors is achieved in the derived filter topologies; also only grounded capacitors
are required. The resonant frequency of the filters can be electronically controlled by an appropriate dc current. In addition,
the derived filters offer the feature of orthogonal adjustment between the resonant frequency and Q factor. The behavior evaluation of the proposed filters has been performed through a test chip prototype fabricated in AMS
0.35 μm CMOS technology. 相似文献
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A novel Multiple Input Single Output (MISO) universal biquad filter topology realized using Current Feedback Operational Amplifiers
(CFOAs) is introduced in this paper. With regards to the corresponding already published MISO universal biquads with CFOAs,
the proposed topology simultaneously offers the benefits of employing only grounded capacitors, absence of any imposed constraint
related to the values of input signals, and orthogonal adjustment between the quality factor and resonant frequency of the
filter. The operation of the proposed biquad has been verified through experimental results by utilizing the commercially
available AD844 CFOA discrete component. 相似文献
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Novel Single Input Multiple Output (SIMO) and Multiple Input Single Output (MISO) universal filter topologies of arbitrary order and type are introduced in this paper. The proposed topologies have been realised by employing Square-Root Domain (SRD) technique. An offered benefit of the universal filter topologies is that only grounded capacitors are required for their implementations and the resonant frequency of the filters can be electronically controlled by an appropriate dc current. The proposed universal filters simultaneously offer all the five standard filtering functions i.e. Lowpass (LP), Highpass (HP) and Bandpass (BP), Bandstop (BS) and Allpass (AP) frequency responses. In addition, the SIMO topology is generic in the sense that it can yield four different stable filter configurations. Two design examples are provided in each configuration and the correct operation of the corresponding topologies has been evaluated through the PSPICE software with BSIM 0.35-µm CMOS process model parameters. 相似文献
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针对非协作通信中多输入多输出(MIMO)信号的盲调制识别,该文提出一种基于独立分量分析(ICA)和特征提取的调制识别算法。根据空分复用MIMO系统各发送天线上信号的独立性,利用ICA算法从接收的混合信号中分离出发射信号。为实现全盲条件下的调制识别,在进行ICA分离前,利用最小描述长度(MDL)准则估计发射天线数。在得到发射信号之后,首先利用6阶累积量、循环谱和4次方谱算法构造4个特征参数,然后利用分层结构的神经网络分类器识别信号的调制类型。仿真结果表明,所提方法可在较低信噪比下对{2PSK, 2ASK, 2FSK, 4PSK, 4ASK, MSK, 8PSK, 16QAM}8种MIMO信号进行有效识别,当发送天线数为2、接收天线数为5、信噪比为2 dB时,识别率可达到98%以上。 相似文献
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DuJiang PengQicong 《电子科学学刊(英文版)》2004,21(6):441-448
This paper investigates the blind algorithm for channel estimation of Orthogonal Frequency Division Multiplexing-Multiple Input Multiple Output (OFDM-MIMO) wireless communication system using the subspace decomposition of the channel received complex baseband signals and proposes a new two-stage blind algorithm. Exploited the second-order cyclostationarity inherent in OFDM with cyclic prefix and the characteristics of the phased antenna, the practical HIPERLAN/2 standard based OFDM-MIMO simulator is established with the sufficient consideration of statistical correlations between the multiple antenna channels under wireless wideband multipath fading environment, and a new two-stage blind algorithm is formulated using rank reduced subspace channel matrix approximation and adaptive Constant Modulus (CM) criterion. Simulation results confirm the theoretical analysis and illustrate that the proposed algorithm is capable of tracking matrix channel variations with fast convergence rate and improving acceptable overall system performance over various common wireless and mobile communication links. 相似文献
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研究了在多输入多输出正交频分复用系统(MIMO—OFDM)中,利用矢量简化星座算法(VRCA)进行盲均衡。矢量简化星座算法(VRCA)在迭代过程中最小化VCRA代价函数,他由落入不同4个象限的接收信号矢量(也就是一个OFDM码元)与他们对应的简化星座点差值的模值平方构成。VCRA能够很好地对MIMO-OFDM系统进行均衡,同时补偿信道造成的相位旋转。这去除了矢量恒模(VCMA)算法不能解决的相位旋转问题。 相似文献