共查询到18条相似文献,搜索用时 203 毫秒
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将光CDMA技术应用到无线光通信中。提出了基于脉冲位置调制的二维大气无线光CDMA通信系统,并分析了该通信系统的性能。考虑多用户干扰、APD噪声以及热噪声等干扰因素的影响,采用数值分析的方法,详细分析了大气湍流引起的大气闪烁对二维无线光CDMA通信系统误码率的影响。结果表明,大气闪烁是影响二维无线光CDMA系统误码率性能的一个重要因素;当大气闪烁的对数方差较小(如σ2s=0.1)时,该系统可以实现高速率通信;当大气闪烁的对数方差较大(σ2s≥0.2)时,在有限的光功率条件下,该系统难以实现通信,需要采用信道编码技术来提高系统的误码率性能。 相似文献
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截短的单重合码对降低FFH-OCDMA系统差拍噪音的研究 总被引:2,自引:1,他引:1
在相同的系统结构下,提出一种截短的单重合码来有效降低差拍噪音对快跳频光码分多址(FFH-OCDMA)系统误码率性能的影响,并对其进行了理论分析和数值模拟.结果表明,当同时用户数较多时,该方案能显著改善FFH-OCDMA系统的误码率性能. 相似文献
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干扰消除是无线光码分多址(CDMA)通信系统中的一项关键技术。分析了基于递归最小二乘(RLS)算法的盲多用户检测算法的原理及性能,并将其应用于采用光正交码的无线光CDMA系统中。讨论了该系统中遗忘因子的选取原则及其对算法的收敛性和系统误码率性能的影响。为了克服固定遗忘因子所带来的矛盾,提出了一种改进的变遗忘因子RLS盲多用户检测算法,并对遗忘因子进行了修正。结果表明,采用改进的方法后系统能获得较快的收敛速度和跟踪速度,收敛时的估计误差也较小,而且信号干扰比由传统算法的6dB提高到9dB。说明采用变遗忘因子的RLS算法不仅适合于采用光正交码的无线光CDMA系统,而且跟踪期望用户信号的性能良好。 相似文献
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为了抑制光码分多址中的多址干扰及多噪音,提出了一种引入光硬限幅器及基于最大值判决的并行干扰抑制器的光码分多址系统.在系统中存在APD噪音及热噪音的情况下,研究了系统对多址干扰的抑制作用.系统采用光正交码作为地址码,APD作为光电检测器,分析推导了系统的误码率表达式.根据所得的误码率表达式,进行了数值仿真,比较了该方法与其他方法的多址干扰抑制效果.研究结果表明:与现有其他有效方法(单比特引入一个光硬限幅器、单比特引入两个光硬限幅器、多比特传输、多比特引入光硬限幅器、基于最大值判决的并行干扰抑制器等)相比,本系统对多址干扰的抑制作用优于并行干扰抑制器、多比特传输、多比特引入光硬限幅器方法;当接收功率较低时,该系统优于引入双光硬限幅器的方法,因此可以有效的抑制多址干扰及多噪音. 相似文献
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Influence of satellite vibration on optical communication performance for intersatellite laser links
For intersatellite laser links, vibration-induced pointing jitter severely influences the communication quality as a result
of intensity fluctuation. In this paper the probability density function of normalized intensity at the receiver is derived
in the presence of pointing jitter taking consideration of bias error. Accordingly, the scintillation index is developed to
identify the impact of bias error on intensity fluctuation. Furthermore the bit error rate (BER) is obtained as a function
of the beam divergence angle and vibration variance. Qualitative analysis is also given, and the numerical simulation is carried
out for demonstration. Results suggested that bias error has a significant detrimental impact on optical terminals which should
be considered in system design. This work can benefit the intersatellite optical system design. 相似文献
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In this paper, we analyze the outage probability of the radio over intersatellite optical wireless communication system in the presence of satellite vibration with bias error. The lower-based Mach–Zehnder modulator, optical booster amplifier and optical preamplifier are employed. First, the models of the proposed system and channel are given. Then the outage probability for a given bit error ratio (BER) of a quadrature phase shift keying signal is obtained in the presence of satellite vibration with bias error. Numerical results of outage probability with different bias error and average BER are given. Results indicate that the outage probability is obviously influenced by the pointing error and the optimum telescope diameter to minimize the outage probability exists. With the same pointing error condition, the value of the optimal telescope diameter will increase with the reduction of the given average BER. 相似文献
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在恒星辐照度谱模型的基础上,根据卫星轨道理论及恒星数据库建立仿真实验系统,对低轨卫星与中继卫星间(LEO_GEO)、中继卫星间(GEO_GEO)、低轨卫星间(LEO_LEO)三种典型的星间激光链路进行了仿真研究,深入分析了恒星背景噪声对卫星光通信终端跟瞄子系统的影响规律、背景光功率等特性。仿真结果表明:对于视场较大的LEO终端,恒星进入视场的概率约为7%~10%,而对于视场较小的GEO终端,恒星进入视场的概率仅为0.05%,恒星背景光功率约为10-13~10-11W。该项工作对星间激光链路设计、光通信系统参数优化等工作具有一定指导意义。 相似文献
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S. Kaur 《Opto-Electronics Review》2019,27(1):10-13
The welcome and adaptation of optical wireless technology by the modern era has brought forward the concept of an inter-satellite free-space optical communication system. In the present work, I study the combined effect of selection of different operating wavelengths and detector types along with the pointing errors at the transmitter and receiver side on the performance of an inter-satellite free-space optical link. The link performance has been optimized by measuring and analyzing the bit error rate and quality-factor of received signal under different scenarios. Performance of the inter-satellite link has also been investigated considering different modulation formats and data rates for LEO and MEO distances. 相似文献
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空间光通信中基本振动对误码率的影响分析 总被引:1,自引:0,他引:1
在探讨卫星振动对空间光通信系统误码率所产生的影响时,有必要分析不同振动类型的影响问题。为了使讨论简单,本文主要侧重对正弦振动进行分析。分析结果表明,当振动持续时间为整周期时,误码率仅为振幅的函数,此时误码率随振幅的增加迅速上升,而与振动频率无关;当振动持续时间为非整周期时,误码率随时间的增加而波动,波动的起伏逐渐减小,误码率趋于仅与振幅有关的常数。该项工作为今后研究卫星复杂振动对空间光通信的影响打下了基础,同时也为研究对卫星振动影响的补偿分析提供了有意义的参考 相似文献
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Acquisition performance analysis for intersatellite optical communications with vibration influence 下载免费PDF全文
《中国物理 B》2020,(1)
A stable and accurate pointing, acquisition system is an important part of initially building intersatellite optical communication links. Satellite platform vibration can cause the system instability and reduce the system precision in building and maintenance of a satellite optical communication system. In this paper, vibration influence is consciously discussed by acquisition time for intersatellite optical communications. Analytical expression of acquisition possibility is derived, taking the scan parameters and platform vibration into account, and vibration influence on the multi-scan acquisition time is also presented. The theoretical result calculated by the proposed analytical expression is approximate to the result by the Monte Carlo simulation. 相似文献
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The bit error rate (BER) performance of an optical soliton communication system is analyzed. Based on the jitter variance equation and the chi-square distribution for the amplified spontaneous emission noise, an analytic expression for the BER calculation is obtained. We have investigated the effects of Gordon-Haus jitter, which is due to the random phase shift of the soliton individual central wavelength induced by the amplified spontaneous emission noise of the amplifiers. Very good agreement has been obtained between our theory and the reported experimental results. 相似文献