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基于MMSE估计准则对TH-PPM UWB多径环境下的系统接收性能进行了分析。首先介绍了TH—UWB信道的传播特征,对IEEE UWB信道模型CM1做了仿真,并分析了MMSE多径信道估计特性,在此基础上对幅值最强两条多径信号的多径延时和多径幅值误差的标准方差进行了仿真,结果表明信号越强延时估计误差越小。最后对采用MMSE估计接收和参数已知接收两种方式下系统的性能进行了仿真,结果表明采用MMSE信道估计的Rake接收机性能可以达到信道参数完全已知的Rake接收机性能。 相似文献
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软件GNSS中频信号模拟器 总被引:1,自引:0,他引:1
由于具有结构灵活、开放性强以及成本低的优势,软件GNSS(Global Navigation Satellite System)信号模拟器可成为GNSS接收机设计验证的高效平台。面向GPS/Galileo组合系统,阐述了软件GNSS中频信号模拟器的架构与实现,主要功能模块包括卫星星座仿真、接收机轨迹生成、传播通道特性仿真(包括电离层模型、对流层模型、多径模型、干扰模型)、数字中频信号生成。最后,对这一信号模拟器所产生的GNSS信号(包括GPS L1 C/A,GalileoE1 CBOC)进行了验证。 相似文献
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针对60 GHz芯片间无线互连信道中存在的多径衰落问题,将匹配滤波器和最小均方误差算法应用到60 GHz脉冲通信系统,重点分析多径信道下采用最小均方误差合并算法的RAKE接收机的误码性能。在IEEE 802.15.3c信道模型的基础上,对采用不同合并方式、不同干扰用户数目下的RAKE接收机误码性能进行了研究。仿真结果表明,随着干扰芯片数量的增加,引入匹配滤波器和最小均方误差算法的RAKE接收机不仅降低了接收机的采样率,而且有效提高了系统抗多用户干扰的能力,为芯片间无线互连系统的RAKE接收机设计提供了技术参考。 相似文献
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BOC(Binary Offset Carrier)信号是卫星导航中一种新的信号体制,对其中频信号模拟是验证基带处理算法的重要基础。针对BOC信号相关函数具有多个峰值特点,中频信号模型考虑了对相关峰值有影响的因素,并综合了信号从卫星到接收机传播中的多普勒效应、多径效应和噪声,以及接收机的处理等过程,以模块化结构进行了实现,并给出其中的运行结果。 相似文献
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提出一种多信道条件下带有Low-IF接收机的新型模数信号接收处理方法,一般Low-IF接收机中,镜频信号会对期望信号造成干扰。在该文方案下,由模拟复带通滤波器完成信道选择,干扰信号通过采用DLMS算法的FIR自适应滤波器消除。仿真分析表明,该方案对AD转换器复杂度要求低,有利于工程实现,而且能很好抑制邻近信道信号干扰,提高系统性能。 相似文献
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OFDM是一项能有效对抗高速无线通信中多径衰落的关键技术,为了进一步提高OFDM系统的误码性能,许多信道编码技术已被应用于OFDM系统中,二元域LDPC码以其近香农限的误码性能和较低的译码复杂度成为研究的热点。在AWGN信道下,多元域LDPC码比等效码长的二元域LDPC码有更好的纠错性能。本文提出了一种将多元域LDPC码经过MPSK调制后用于OFDM系统的新方法。仿真结果表明,在多径衰落信道下,通过合理选择多元LDPC码域的阶数和调制的方法,多元域LDPC编码的高阶调制OFDM系统比等效码长的二元域LDPC编码OFDM系统具有更好的性能,并且由于采用了多元域LDPC的快速BP译码,译码复杂度只是稍有增加。 相似文献
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本文首先介绍了DS-SS系统的基本原理,为了克服多重路径衰落DS-SS系统中采用了Rake接收机,本文进一步介绍了Rake接收机的设计原理,最后通过MATLAB仿真了Rake接收机的信道估算结果和其性能. 相似文献
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多通道技术可以用来提高系统的频带宽度,是实现分辨率优于0.1 m的超高分辨率机载合成孔径雷达(SAR)系统的一种有效的技术途径。该文针对实际雷达系统中采用的单通道宽带信号发射、8通道下变频接收来完成宽带信号收发的方案,提出一种对该收发系统的幅相误差进行测量和校正的方法,该方法采用空间闭环辐射提取宽带收发通道的幅相误差,采取具有频偏误差修正的矢量网络分析技术完成多通道接收单元中各子通道幅相误差的提取,将两者结合用于补偿整个系统误差对信号合成和成像处理所带来的影响。实际测试数据和外场飞行试验结果验证了该系统测量和校正方法的有效性和可行性。 相似文献
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Omidi M.J. Gulak P.G. Pasupathy S. 《Selected Areas in Communications, IEEE Journal on》1998,16(9):1616-1629
Joint data and channel estimation for mobile communication receivers can be realized by employing a Viterbi detector along with channel estimators which estimate the channel impulse response. The behavior of the channel estimator has a strong impact on the overall error rate performance of the receiver. Kalman filtering is an optimum channel estimation technique which can lead to significant improvement in the receiver bit error rate (BER) performance. However, a Kalman filter is a complex algorithm and is sensitive to roundoff errors. Square-root implementation methods are required for robustness against numerical errors. Real-time computation of the Kalman estimator in a mobile communication receiver calls for parallel and pipelined structures to take advantage of the inherent parallelism in the algorithm. In this paper different implementation methods are considered for measurement update and time update equations of the Kalman filter. The unit-lower-triangular-diagonal (LD) correction algorithm is used for the time update equations, and systolic array structures are proposed for its implementation. For the overall implementation of joint data and channel estimation, parallel structures are proposed to perform both the Viterbi algorithm and channel estimation. Simulation results show the numerical stability of different implementation techniques and the number of bits required in the digital computations with different estimators 相似文献
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Multiple input multiple output (MIMO) systems showed good utilization of channel characteristics. In MIMO systems multiple
signals are transmitted using multiple antenna system. This provides each receiver the combined signals and hence, array processing
techniques helps in reducing the effects of interference among them. In this paper we devise the use of pre-coded MIMO system
to reduce the effects of frequency selectivity and hence, enhance the systems capacity and/or reduce the bit error rate. In
this technique we introduce a temporal pre-coder on each antenna signal; this creates a deterministic multi-path signals similar
to signals received when the channel is multi-path fading channel. The same antenna signal will arrive at each receiver forming
orthogonal sub-space and the receiver will be simple add and delay of the received signals. Ant colony optimization is used
in this paper to select the best pre-code. Results showed that we can diagonalize the channel matrix and practically eliminate
the interference for frequency selective fading channel. Simulation of two transmitting two receiving antennas pre-coded MIMO
system showed that the capacity can be doubled. 相似文献
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Broadband wireless communication users for 5G networks are primarily implemented in a complicated environment; the complex environment of time-varying multi-path propagation characteristics will seriously affect the performance of communication. One of the core technologies to overcome this problem is to introduce the environment adaptive technique—time reversal in the wireless link. Further, the problem of a Wiretap Channel in physical layer security research has become a popular research topic in recent years. To resolve the physical layer wiretap channel and multi-path fading problems in wireless channels, a novel concept of combining time reversal technology with physical layer security technology is proposed. In this paper, a physical layer secure transmission scheme based on the joint time reversal technique and artificial noise at the sending end is proposed for the wireless multi-path channel. First, in a typical wiretap channel model, the time reversal technique is used to improve the security of the information transmission process by using the properties of spatial and temporal focusing. Second, as the information is easily eavesdropped near the focus point, artificial noise is added to the sending end to disrupt the eavesdropping capability of the eavesdropper. Finally, due to the complexity of the multi-path channels, the influence of the antenna correlation on the system security performance is considered. Compared with the existing physical layer security schemes, theoretical analysis and simulation results show that the proposed scheme has a higher secrecy signal-to-noise ratio, a higher rate of secrecy, and a lower bit error rate of legitimate user. 相似文献
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Continuous wave (CW) interference can cause severe performance degradation of global navigation satellite system (GNSS) receiver. In analysing the code tracking performance of pilot channel under CW interference, the signal spectrum consists of discrete spectral lines and the interference term of the correlator output shows the characteristics of direct current or sine. Thus the traditional assumptions that the interference obeys the Gaussian distribution and that the spectrum of the signal is continuous no longer hold. Considering this fact, this paper presents the analytic expressions of the code tracking error bound for the early-minus-late power (EMLP) discriminator and the dot-product (DP) discriminator. The derived expressions can be used to assess the susceptibility of code tracking performance under CW interference for the pilot channel of GNSS signals. Then the GPS L5 signal is taken as an example of the application of the derived mathematic expressions. The effects of finite front-end bandwidth, correlator spacing, and discrete spectrum of pseudo-random noise (PRN) code on performance are discussed. It is shown that the code tracking performance can be improved by choosing proper receiver parameters and some of the L5 codes are more vulnerable to the interference compared with the average level. 相似文献
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IS-95是北美制定的基于CDMA技术的无线空中接口标准,本文给出了IS-95反向信道调制和解调过程的数学模型。一般认为Nakagami(m)分布较好地描述了多径衰落信道,本文分析了IS-95反向信道在Nakagami(m)衰落信道下的误码率,结果可以用来综合分析系统和信道的不同参数对系统性能的影响。 相似文献