共查询到20条相似文献,搜索用时 109 毫秒
1.
针对智能交通可见光通信系统采用OOK、PPM和DPIM等调制方式系统的接收机信噪比不理想的问题,研究双头脉冲间隔调制(DHPIM),分析DHPIM对系统接收机信噪比的影响。首先介绍DHPIM调制工作原理,比较各种调制方式系统占用的带宽,接着分析比较了几种典型天气条件下DHPIM调制系统接收机信噪比,最后在同一种天气下,分析比较了系统采用DHPIM等多种调制方式接收机的信噪比。仿真结果表明,在同一天气下DHPIM调制系统接收机信噪比高于OOK、PPM和DPIM等调制系统接收机信噪比。因此与OOK、PPM、DPIM相比,DHPIM可显著提高系统接收机信噪比,更适合于智能交通可见光通信系统。 相似文献
2.
3.
为了满足卫星导航接收机整机性能快速、精确测试的需求,实现对导航接收机性能的自动测试,构建了一种基于NI PXI硬件平台,采用导航信号模拟器、虚拟仪器技术和Microsoft Visual Studio 2008软件进行开发的卫星导航接收机自动测试系统。系统实现了多导航接收机的定位精度、冷启动首次定位时间、热启动首次定位时间、捕获灵敏度、速度精度的并行自动测试。良好的人机交互界面与多接收机并行测试的稳定运行,大大缩短了测试时间,提高了测试效率。通过对北斗导航接收机大量测试,结果表明该卫星导航接收机快速测试系统对于导航接收机整机性能并行测试快速、有效。 相似文献
4.
5.
6.
7.
在无线通信中,超宽带接收机的抗干扰性是接收系统的重要技术,而误码率是抗干扰性重要的评价指标;为了提高超宽带接收机的接收性能和抗干扰能力,设计了变步长LMS算法的超宽带Rake接收机;通过建立系统模型,分析LMS算法基本原理且提出改进思路,将改进的变步长LMS算法应用于Rake接收机,进行建模仿真;结果显示变步长LMS算法的Rake接收机接收性能提高,误码率迅速降低到10-1,有效改善了接收机抗干扰能力。 相似文献
8.
9.
锁相环解调Chirp-UWB通信系统仿真研究 总被引:1,自引:0,他引:1
在通信系统优化的研究中,通信系统的质量优劣主要取决于接收机的性能。设计结构简单,复杂度低,可靠性高的Chirp-UWB接收机一直是系统实现的重点和难点。针对匹配滤波接收机解调Chirp-UWB系统成本高、灵活性不好等问题,设计了锁相环解调的Chirp-UWB接收机方案,调整锁相环参数使其工作在载波跟踪状态是方案的核心内容。研究了系统结构原理、各部分电路设计,通过Simulink软件进行建模和仿真,并对接收机系统进行性能分析。同时利用锁相环解调方案对发射机部分进行了进一步改进。从系统结构,误码率等方面将锁相环解调系统与匹配滤波解调系统进行了分析比较。仿真结果表明,改进锁相环解调Chirp-UWB系统电路成本低,灵活性好,抗干扰能力强,传输可靠性高。 相似文献
10.
11.
12.
为了消除超宽带通信中数据辅助(DA)的平均发射参考(ATR)接收机的判决错误传播风险,提出加入FEC译码反馈机制,用译码判决输出来反馈更新相关模板的思路。比较选择出适合的Turbo乘积码(TPC),据此形成了一种TPC译码反馈的改进DA-ATR接收机。对其性能进行了分析和多径信道仿真,结果表明:该接收机能有效消除上述风险,检测性能优于单纯TPC纠错的一般ATR接收机,约有1 dB信噪比增益优势。 相似文献
13.
针对垂直分层空时方案(VBLAST)传统检测存在误层传输效应及复杂度高的问题,提出了一种多用户MIMO-MC-CDMA下行链路系统中基于QR分解的VBLAST非线性模代数预编码算法,该算法首先采用QR分解获得预编码矩阵,然后在发射端MC-CDMA子载波信道间进行非线性模代数THP预编码,可以有效地消除分层空时码的误层传输效应。在接收端采用迫零与最小均方误差准则,降低了下行接收机的复杂度。仿真结果表明,提出的算法比传统检测算法有效改善了系统的误码性能。 相似文献
14.
In this article, we propose a cyclic delay diversity (CDD) transmission scheme for unique word (UW) OFDM system, which is denoted as CDD-UW-OFDM. In our proposed CDD-UW-OFDM system, the first transmit antenna transmits a UW-OFDM and then, for every UW-OFDM block, the i-th transmit antenna transmits a cyclically delayed version of the symbols transmitted at the first transmit antenna. With this proposed CDD-OFDM system, each antenna transmission is a UW-OFDM. Also, at the receiver under a certain condition on the cyclic delay amounts, the received signal is equivMent to that of a single transmit antenna UW-OFDM transmission with a longer multipath channel. We design the lengths of UW and cyclic delays to achieve the full multipath and spatial diversities for the CDD-UW-OFDM system when the linear MMSE receiver is used. We then present some simulation results to illustrate the claimed performance of the proposed system. 相似文献
15.
采用一种新型的分层空时编码——随机分层空时编码(RLST),针对其在TD-LTE系统中的应用进行了研究,通过对理论的分析,进行了RLST和V-BLAST在CDMA结构下的性能比较,并对应用RLST结构的接收机在不同信道环境下的性能比较,最后通过仿真结果表明了使用RLST结构的优越性,也证明了针对RLST结构提出的迭代多用户接收算法的正确性。 相似文献
16.
立足于GPS卫星信号仿真技术,提出了基于DSP+FPGA的多通道GPS卫星信号仿真器硬件设计方案,概略介绍了硬件系统的基本架构,详细给出了基于此上的软件结构和程序流程,最后通过实验验证了该方案的可行性。实验结果表明,该方案设计的GPS仿真器信号逼真度高、可编程性强、使用灵活,并具有一定的动态性能,为GPS接收机的性能检测提供了有益的支持。 相似文献
17.
18.
It has been shown that transmit correlation causes a signal-to-noise ratio (SNR) loss in the zero forcing (ZF) receiver for
V-BLAST (Vertical Bell LAbs LAyered Space-Time) system. In this paper, we investigate the transmit correlation effect on the
ZF receiver with successive interference cancellation (SIC). We show that such an unfavorable condition leads to twofold effects
on the performance degradation. In addition to the immediate SNR loss, the transmit correlation can increase the propagation
factor to spread decision error significantly. These two effects are evaluated analytically. We derive the probability density
function (pdf) of the effective SNR at each decoded stream, and hence accurately quantify the SNR loss. We also calculate
the decision error propagation factor in terms of its second moment. In particular, we show that transmit correlation can
cause a stable component of error propagation which does not decline during the SIC procedure. Finally, we conduct the simulation
to verify the analytical results. 相似文献
19.
虽然无先导卡尔曼滤波(UKF)技术在性能上要优于一阶线性化的扩展卡尔曼滤波(EKF)技术,但是对于改进型Logistic混沌映射的扩频通信系统,UKF运算时间长,算法复杂。针对上述缺点以及改进型Logistic映射的泰勒展开式最高项为二阶的特点,提出将二阶EKF运用到接收系统中,该接收系统能精确到泰勒展开式的二阶,达到与UKF相同的性能。相比UKF的复杂算法更加简单,运算速度也更快。仿真实验表明,虽然二阶EKF与UKF的误码率相同,但在运算速度与复杂度方面均优于UKF。 相似文献
20.
In this paper, by introducing orthogonal space-time coding scheme, the multiuser CDMA systems with different space time codes
are given, and corresponding system performance is investigated over Rayleigh fading channel. A low-complexity multiuser receiver
scheme is developed for space-time coded CDMA systems. The scheme can make full use of the complex orthogonality of space-time
coding to simplify the high decoding complexity of the existing scheme. Compared to the existing scheme with exponential decoding
complexity, it has linear decoding complexity. Based on the performance analysis and mathematical calculation, average bit
error rate (BER) of the system is derived in detail, and tight closed-form approximation expressions of BER are attained.
Simulation results on average BER are in agreement with the theory analysis. The results show that the proposed scheme can
achieve almost the same performance as the existing scheme. Moreover, on the condition of same system throughput and concatenation
of channel code, the given full-rate space-time coded CDMA system has lower BER than the full-diversity space-time coded CDMA
systems. 相似文献