共查询到20条相似文献,搜索用时 15 毫秒
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《Vehicular Technology, IEEE Transactions on》1981,30(1):37-42
An analysis of the effect of multiple narrow-band interfering signals on the probability of error in a frequency-hopped differential phase shift keyed (FH-DPSK) spread-spectrum communication system is given. A basic assumption in this analysis is that the sum of the outputs from an n-subchannel receiver can be modeled as a Gaussian random variable. Subject to this assumption, numerical evaluation of the probabilities of error for both nonfading and Rayleigh fading channels are presented. The results indicate that for n ≥ 32 adequate performance can be achieved even when each of the subchannels has an interfering signal present. 相似文献
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GongXiangyang HuGuangrui 《电子科学学刊(英文版)》2002,19(2):172-174
During the past research,Direct Sequence(DS) Spread Spectrum(SS) signal is modeled as stationary in most cases.Cyclostationary model for SS signal is introduced in this letter.Compared with stationary model,cyclostationary model can preserve more information,and its advantages are shown throrgh example. 相似文献
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YingXiaofan ChuZhenyong TianHongxin YiKechu 《电子科学学刊(英文版)》2004,21(4):322-327
The proposed scheme is based on Discrete Fourier Transform (DFT) domain processing. The key technology of this scheme is jamming parameters‘ accurate estimation and jamming reconstruction. Compared with the “threshold exciser”scheme.the proposed scheme can eliminate more jamming energy on the whole frequency band with the minimum loss of useful signal energy. As shown in the research and simulation, the proposed scheme is much better than the “threshold exciser” scheme, especially in the case of high power jamming whereas the “threshold exciser” scheme might be invalid. 相似文献
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随着计算机网络的迅速发展,扩频通信由于其便于为计算机网络提供物理接口信道而得到日益广泛的应用。然而有些厂家为一己私利误导用户,宣称:扩频通信系统在国外是免许可的,台站不用审批,言外之意在国内也不用办理设台审批手续;即使无线电管理部门进行监测,也难以发现,因为其信号可以在噪声下传输;同时扩频通信不用审批的原因是系统不怕干扰,所以也就不用无线电管理部门管理。上述的种种说法给我国实施对扩频台站的审批管理加大了难度,使扩频通信系统的干扰矛盾日趋增多,造成空中电波秩序的混乱。本文从扩频通信系统的基本原理出… 相似文献
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在扩频通信中,Rake接收是抵抗多径衰落的有效方法。本文首先介绍无线移动通信的信道特性,然后对Rake接收的基本原理和接收机结构进行详细描述,并对Rake接收性能进行了仿真比较。仿真结果表明,在多径信道条件下,Rake接收方式能很好的改善接收系统误码性能;采用GOLD序列扩频比m序列扩频方式时,Rake接收方法性能提高的更明显。 相似文献
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直接序列扩频通信系统研究及仿真 总被引:2,自引:0,他引:2
直接序列扩频通信系统因其抗干扰性强、隐蔽性好、易于实现码分多址(CDMA)、抗多径干扰、直扩通信速率高等众多优点,在个人通信网、无线局域网、第三代移动通信、卫星通信以及军事战术通信等领域得到广泛应用.本文以扩频通信理论为基础,用MATLAB工具箱中的Simulink通信仿真模块和MATLAB函数对直接序列扩频通信系统进... 相似文献
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Sousa E.S. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1992,38(6):1743-1754
Results on the modeling of interference in a radio communication network and performance measures for the link as a function of distance are presented. It is assumed that a transmitter-receiver pair in a radio network is affected by a set of interferers, using the same modulation and power, whose positions are modeled as a Poisson field in the plane. Assuming a 1/rγ propagation power loss law, the probability distributions for the noise at the receiver are found to be the stable distributions. Results are given for the probability of symbol error and link capacity as a function of the distance between the transmitter and receiver for direct sequence and frequency hopping spread spectrum schemes. It is found that the frequency hopping schemes are inherently superior and their performance is not dependent on the synchronization of the hopping times for the different users 相似文献
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本文在加+1到M系列的正交系列集合基础上,提出一种同步多路接续频谱扩展通信方式.由于在通道之间完全同步的情况下不存在多路干扰,多路通信能力获得改善,功率控制方面的远近问题淡化了,外部干扰得到消除.通过理论分析,文中给出了通道间不同步时的平均误差概率,还讨论了在此情况下多路通信能力下降,功率控制方面的远近问题,以及通道间扩展码不能良好地同步的情况. 相似文献
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以Matlab提供的可视化仿真工具Simulink搭建直接序列扩频通系统仿真模型,利用Simulink对直接序列扩频通系统的发射机模块和接收机模块进行仿真设计,通过传输过程中各个波形和频谱变换图,研究直扩系统误码率、信噪比和扩频增益的关系。在给定的仿真条件下,运行测试仿真模型,结果表明,该系统信噪比较高,性能较好,且在误码率保持不变的情况下,增加直扩通信系统的扩频增益可以增加输出端的信噪比。 相似文献
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RS码作为一种性能良好的纠错码,广泛应用于无线通信系统中。结合自组网扩频定位通信系统功能目标,本文分析了无线定位通信系统工作流程对纠错的指标需求,选择了RS的码作为纠错码,详细分析了不同长度的RS码对系统抗干扰性能影响并对RS码译码中的BM迭代译码算法进行了优化。 相似文献
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针对传统雷达电磁辐射干扰分析方法的不足,首先在时域符号级详细分析了雷达对扩频通信系统电磁辐射干扰的机理,推导得出扩频通信系统在脉冲雷达干扰下的误码率公式和曲线;然后利用建立的雷达电磁干扰仿真模型,对扩频通信系统采用不同扩频因子以及不同频率隔离度时的受扰性能进行了仿真分析,其结果与理论分析结果较为吻合。最后利用所得结论计算给出了微波频段5种典型雷达与扩频通信系统的频率-距离隔离关系。研究结果证明,本方法能在更深层次上揭示雷达辐射干扰的本质,提高频谱利用效率。 相似文献
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The capability of the time-frequency distributions (TFDs) to properly represent a single as well as multiple component signals in time and frequency permits the application of a new approach for interference excision in spread spectrum communication systems. The instantaneous frequency (IF) estimate from the TFD is used to construct a finite impulse response filter that reduces the interference power with a minimum possible distortion of the desired signal. The proposed technique is therefore a case of open-loop adaptive filtering. Three- and five-coefficient zero-phase excision filters are considered. Closed-form expressions of the improvement of SNR at the receiver correlator output using the TFD-based adaptive filtering are derived for two extreme cases of time-varying interferers, namely, those of fixed frequency sinusoids and randomly changing instantaneous frequencies. Simulation results including the bit error rates are presented for both swept and frequency hopping jammers 相似文献
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A new double-filter receiver for spread spectrum wireless systems is presented. The receiver exploits the inherent diversity due to the small delay difference between the multipaths which may not be exploited by the conventional RAKE receiver. The bit error rate performances of both the coherent and the noncoherent detectors are analyzed and compared with the ideal RAKE receiver and the matched filter bound. We also examine the best and the worst cases of a three-path fading channel for the proposed receiver. Optimum pulse shapes under various channel conditions are designed. Implementation issues in code-division multiple access systems are discussed. The numerical results show that the proposed receiver achieves significant gains for a given spreading factor under a complexity constraint. 相似文献
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