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1.
王坤 《信息技术》2007,31(12):77-80
超宽带信号经多径信道传播会产生严重的时间弥散,采用Rake接收是提高超宽带接收机性能的重要手段。文中首先介绍了加性高斯白噪声信道模型和IEEE802.15.3a标准信道模型。通过比较分析几种典型调制的超宽带冲激无线电信号的最佳接收机,推广到Rake接收机的性能分析。重点分析并仿真了不同信道、不同调制方式、不同判决方式、不同合并方式、不同速率的情况下Rake接收机的性能。  相似文献   

2.
室内环境中超宽带(UWB)信号经过密集多径传播会产生严重的时间弥散,采用Rake接收是提高UWB接收机性能的重要手段.在IEEE802.15.3a工作组推荐的信道模型基础上,采用脉冲位置调制(PPM)方式对超宽带信号在不同信道情况下不同Rake接收机的性能进行了系统的研究,可以在选择Rake接收机时,为综合考虑系统复杂度和性能改善的优化问题提供有价值的参考.  相似文献   

3.
超宽带信号在室内环境中将经历密集多径传播,产生严重的时间弥敞。采用Rake接收是提高超宽带接收机性能的重要手段。该文针对采用BPSK调制的超宽带系统,推导出密集多径信道下Rake接收机的误码性能计算公式,揭示了Rake接收机性能与多径信道参数以及脉冲波形自相关系数之间的关系。针对典型信道模型和脉冲给出了计算实例。  相似文献   

4.
为了解决通信系统仿真模型的不完备性,利用Matlab的组件Simulink搭建了一套模拟信号的传输、接收、分离的接收机通信仿真模型。该模型以同频同调制信号为信源,选取多径瑞利衰落信道模拟仿真实际接收机的工作流程,并且包括信源模块、调制解调模块、信道模块、模拟接收模块、采样滤波模块、信号分离模块等。此外,系统测试了瑞利信道的路径增益对信号盲分离的影响,仿真结果表明信道增益越大,信号越集中,分离效果也相对较好。因此,该仿真系统可以与硬件系统原型相结合,为测试信号提供功能验证,为实际接收机系统运行环境提供参考建议。  相似文献   

5.
针对超宽带跳时PPM信号在不当参数选择时在确定性多径信道可能出现的不同数据符号的误码率不平衡性问题,提出解决TH-PPM调制信号可能存在误码率不平衡这一问题的两种方法,一种是Rake接收机选择动态的判决门限,另一种是改进TH-PPM调制方式,即对待发送的数据符号进行平衡编码。通过理论分析和计算机仿真表明,两种方法都能改善跳时PPM信号在多径环境下存在的误码率不平衡问题,比较而言,平衡编码方法具有实现的简单性以及在对信道变化、Rake接收机信道估计以及合并方式的稳健性。  相似文献   

6.
超宽带信号在无线信道中传播会产生严重的衰落和多径干扰等问题,而在抗多径干扰方面采用Rake接收机的方式是一种行之有效的手段.利用IEEE802.15.3a标准信道模型,采用TH-PPM调制方式对信道冲激响应的特性进行了分析,并对标准信道模型下的A-Rake,P-Rake和S-Rake三种接收机模型在不同的支路下的BER进行了对比分析.从仿真结果可以得出A-Rake为理想接收机性能最佳,相同支路下S-Rake接收机的性能要优于P-Rake接收机,但是随着支路数的增加两者的性能差距也越来越小.  相似文献   

7.
采用分段加权合并的思想,提出了一种新的加权的UWB-ATR接收机,根据接收信号中的多径分布给予各段不同权重,有效压制了噪声乘积项,权重系数由MMSE估计得出.经过理论分析和IEEE CM3多径信道仿真,结果表明该接收机的误码率性能优于一般ATR接收机.  相似文献   

8.
刘树楷 《电子世界》2013,(12):135+231
在移动通信中,由于城市建筑物和地形地貌的影响,电波在传播过程中必然会出现不同路径和时延,即移动通信信道是一种多径衰落信道,这使接收信号将会出现起伏和衰落,影响移动通信系统的通信质量。在CDMA系统中,RAKE接收是一种十分有效的抗多径衰落的技术。所谓的RAKE接收技术就是分别对接收的每一径信号进行解调,然后通过一定的规则进行叠加输出,以达到改善接收性能,增强接收效果的目的。在这种接收模式下,多径信号不仅不是一个不利因素,反而在CDMA系统中变成了一个可供利用的有利因素。本文研究了RAKE接收技术理论,并借助MATLAB软件设计和实现了RAKE接收机仿真程序,接着对不同分集重数、不同分集合并方式下RAKE接收机的性能进行仿真分析。通过仿真可以发现仿真结果与理论分析相符,RAKE接收机在采取多径合并后,能更有效的收集信号能量,恢复出原始信号。三种合并方式中,最大比值合并方式对接收信号信噪比的改善效果最好。  相似文献   

9.
通过对无线通信信道传输特性的讨论,以瑞利信道和莱斯信道为模型,研究在QPSK扩频调制下接收端信号的同步、多径分离与按增益合并.仿真实现了频率选择性慢衰落信道下的一种Rake接收技术,结果表明用他来减小多径衰落是有效的.  相似文献   

10.
为实现时域重叠信号的全概率接收和跨信道信号重构,降低窄过渡带信道化结构的复杂度,提出一种基于调制屏蔽滤波器频率响应屏蔽(Modulation Masking Filter Frequency Response Masking, MMF-FRM)技术的信道化接收机结构.通过对原型屏蔽滤波器进行调制得到两个分支屏蔽滤波器,给出了基于MMF-FRM的窄过渡带滤波器设计方法 .推导出一种基于MMF-FRM的低复杂度信道化接收机结构,该信道化结构解决了多相分解受FRM(Frequency Response Masking)滤波器组限制的问题,并分析了该结构的有限字长性质和纹波系数.用Xilinx System Generator进行了硬件实现与仿真,在采样速率为1 GHz,信道数为8的条件下,提出的信道化接收机结构比多相信道化结构节省74.1%的乘法器资源,比FRM信道化结构节省13.5%的乘法器资源.  相似文献   

11.
林汝景 《电子测试》2020,(2):40-42,65
卫星导航系统主要通过人造卫星作为信号转发的中继站,通过上下行链路建立地球站间的无线通信,可实现大容量、远距离、高覆盖面、低延时的信息传输,而且导航系统存在接收电平低、接收机灵敏度高、接收信号比较微弱、导航信号在同一频率发射、调制、信噪比极低、下行链路容易干扰等问题。系统分析了北斗卫星导航接收机抗干扰主要应用技术;介绍了接收机主要干扰类型;提出了时空二维联合处理(STAP)抗窄带干扰技术模型及最小均方误差滤波器(MMSE)算法;通过仿真研究,该方法抑制窄带干扰效果较好。  相似文献   

12.
A beamspace-time (BT) receiver is proposed for interference suppression and multipath diversity reception in sectored wireless code division multiple access communications. The scheme involves two stages. First, a set of adaptive space-time diversity processors, in the form of beamformer-correlator pairs, is constructed which provides effective suppression of unwanted interference and reception of signals from a prescribed space-time region. Second, the output data obtained by these processors are maximum ratio combined to capture the signal multipath components coherently. The proposed BT receiver is blind in that no training signal is required. The only information required is the signature sequence, timing and a rough estimate of the angle of arrival of the signal for selecting the sector of interest  相似文献   

13.
Lam  W.H. Chang  K.C. Lo  C.M. 《Electronics letters》1999,35(5):374-375
An investigation is presented into the performance of a novel type of sequence estimation equalisation receiver. The receiver incorporates space diversity to further enhance the signal reception in multipath fading environments. It is shown that the receiver complexity is reduced by ~90% with virtually no performance loss compared to that of the MLSE  相似文献   

14.
The reception of a NTSC TV signal using a narrow band receiver is studied. A mathematical model is developed. Based on this model, a computer program is written simulating the transmission and reception of TV signals. The transient oscillations and the noises in the received primary colour signals are analysed revealing that the blue colour signal suffers the most, the red colour signal being second, and the green colour signal has the smallest transient and noise. These results are confirmed by computer simulation.  相似文献   

15.
NHK has developed the band segmented transmission orthogonal frequency division multiplexing (BST-OFDM) scheme for the transmission system of Integrated Services Digital Broadcasting-Terrestrial (ISDB-T). This scheme provides the great advantages of hierarchical transmission and partial reception. To provide commonality with other systems, the transport signal of ISDB-T adopts the MPEG-2 transport stream (TS). However, TS has been designed for neither hierarchical transmission nor partial reception. Thus, to fulfil the requirements of ISDB-T, the TS has been adapted to provide effective hierarchical transmissions and partial reception. This paper describes the TS generation methods used by the remultiplexer for minimizing receiver processing load. Briefly, they are: 1) a method enabling hierarchical transmission and partial reception of a single TS; 2) a method relating a TS packet to a segment of the OFDM signal; 3) a method for interfacing the remultiplexer with a modulator at a single constant clock; 4) a method for reconstructing a serial TS at receivers from hierarchical transmission signals allotted to layers in parallel by an OFDM multicarrier; and 5) a method for correctly recovering the program clock reference (PCR) at a "partial reception" receiver, even if the TS rate of the receiver is different from that of the transmission side.  相似文献   

16.
针对低成本、高性能的广播式自动相关监视(ADS-B)系统的设计需求,研究了ADS-B信号接收技术。基于软件无线电技术,设计了基于1090ES模式的ADS-B信号软件接收机;利用廉价的软件无线电平台(RTL-SDR)及Matlab,对设计进行了验证,实现对民航航班ADS-B信号的实际接收。相对于传统的ADS-B接收机,结构简单,灵活性高,提高了开发效率。  相似文献   

17.
The paper analyses performances of the two lowest data rates of impulse-radio ultra-wideband DPSK physical layer of recently published IEEE 802.15.6 Body Area Networks standard. Two receiver architectures suitable for the reception of symbols with signal structure described in specification of this physical layer, namely duty-cycled sampling receiver and chirp receiver, are introduced. Then, performance of these receiver architectures are analyzed through probabilities of error in different phases of packet reception. Analysis has been performed in the presence of different types of interference; namely frequency modulated ultra-wideband, WiMax and other co-located IEEE 802.15.6 impulse-radio ultra-wideband devices.  相似文献   

18.
Free-space optical communication through atmospheric turbulence channels   总被引:5,自引:0,他引:5  
In free-space optical communication links, atmospheric turbulence causes fluctuations in both the intensity and the phase of the received light signal, impairing link performance. We describe several communication techniques to mitigate turbulence-induced intensity fluctuations, i.e., signal fading. These techniques are applicable in the regime in which the receiver aperture is smaller than the correlation length of fading and the observation interval is shorter than the correlation time of fading. We assume that the receiver has no knowledge of the instantaneous fading state. When the receiver knows only the marginal statistics of the fading, a symbol-by-symbol ML detector can be used to improve detection performance. If the receiver has knowledge of the joint temporal statistics of the fading, maximum-likelihood sequence detection (MLSD) can be employed, yielding a further performance improvement, but at the cost of very high complexity. Spatial diversity reception with multiple receivers can also be used to overcome turbulence-induced fading. We describe the use of ML detection in spatial diversity reception to reduce the diversity gain penalty caused by correlation between the fading at different receivers.  相似文献   

19.
ESM系统对扩谱雷达信号的侦收   总被引:4,自引:0,他引:4  
李国华 《舰船电子对抗》2005,28(3):35-37,53
分析了雷达扩谱信号的特征,针对脉压线性调频信号、相位编码信号的侦收问题,提出了在传统电子侦察接收机上进行改进,在工程应用方面具有很大的推广价值。  相似文献   

20.
为了实现对联合战术信息分发系统( JTIDS)信号的宽带接收,设计了一种基于多相滤波器的信道化接收方法。该方法通过对JTIDS的模拟信道和数字信道进行合理划分,将宽带接收转化为多个窄带接收,然后再结合多相滤波器进行跳频频点检测,以实现全概率的JTIDS信号宽带接收。给出了此信道化接收模型的现场可编程门阵列( FPGA)实现方案,并对仿真和硬件测试结果进行对比分析。仿真与FPGA测试结果表明,该接收模型可以精确实时地接收JTIDS宽带信号。  相似文献   

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