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光码分多址(OCDMA)通信系统中的地址码 总被引:8,自引:0,他引:8
介绍了光码分多址 (OCDMA)系统中的地址码 ,包括光正交码 (OOC)、素数码 (PC)、扩展的素数码 (EPC)、二次同余码 (QC)、扩展的二次同余码 (EQC)和混合码 (HC)等。同时分析了它们各自的性能。 相似文献
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介绍了光码分复用(OCDM)通信系统的编解码器,包括光振幅、相位、频域和可调谐OCDM编解码器等,并在各种编解码器特点、结构、成本和发展前景等方面进行了比较分析。 相似文献
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本文叙述了光频分复用(OFDM)技术的特点,OFDM传输系统的组成及工作原理,扼要地分析了几个关键部件对OFDM传输系统的影响,介绍了OFDM系统中的光器件的主要类型及特性。最后介绍了光频分复用技术在各种通信网中的几种应用。 相似文献
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光纤的容量是很大的,采用波分复用(WDM)技术使网络上的所有节点分享这个巨大的带宽早已成为引人注目的课题,随之也就展开了波分多址(WDMA)媒质按入控制协议的研究。本文介绍了一些基本的媒质接入控制协议,并对它们的性能进行了分析。 相似文献
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采用光码分多址技术的高速计算机局域网 总被引:8,自引:0,他引:8
本文提出一种可行的适于高速计算机网络的光码分多址技术,该网络采用光正交码和光信号处理,以保证实时数据通信。提出的全光结构的快速可调光正交码编码器和解码器,可在光域中用电光开关和光延迟线实现,能支持超高速吞吐量且重构时间很短 相似文献
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基于超连续谱和超结构光纤光栅的波分复用/光码分复用系统 总被引:5,自引:1,他引:4
实验验证了基于超连续谱(SC)和超结构光纤光栅(SSFBG)的波分复用/光码分复用(WDM/OCDM)混合系统,超结构光纤光栅实现了对超连续谱光源的双波段同时相位编解码。由于波分复用/光码分复用系统中信道间干涉和噪声的影响,解码输出脉冲的信号波形出现劣化,自相关曲线旁瓣明显增大,自相关峰展宽至8.2 ps。在非线性放大环镜(NALM)的阈值判决作用下,解码输出脉冲的信号波形质量有了明显的改善,自相关峰宽度压缩至4.8 ps,较好地抑制了自相关曲线的旁瓣和噪声。实验中非线性放大环镜的输入信号峰值功率约为8 mW。 相似文献
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Advanced optical modulation formats have become a key ingredient to the design of modern wavelength-division-multiplexed (WDM) optically routed networks. In this paper, we review the generation and detection of multigigabit/second intensity- and phase-modulated formats and highlight their resilience to key impairments found in optical networking, such as optical amplifier noise, chromatic dispersion, polarization-mode dispersion, WDM crosstalk, concatenated optical filtering, and fiber nonlinearity 相似文献
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混合光波长转换在波分复用光网络中的应用 总被引:2,自引:2,他引:2
在全光网络中,如何合理利用波长转换来降低光网络的阻塞率是一个非常关键的问题。研究了最新的波长转换体系结构和波长转换手段,提出一种全新的混合波长转换方法,在减少网络中波长转换器个数的同时,维持拥塞概率类似于全波长转换。提出了5种不同的波长转换器使用策略,并利用数值模拟的方法,比较了这5种不同的波长转换器使用策略,分析结果,得出了最小化光网络的阻塞概率的波长转换使用策略。结合混合波长转换和波长转换器使用策略,进一步提出了光网络中优化波长转换器配置的遗传算法,通过对14个节点的美国自然科学基金网(NSF Net)的数值模拟,结果表明它是十分有效的,在减少光网络中波长转换器数量,且不增加光网络波长数量的情况下,基本保持原有网络性能。 相似文献
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Chee Kyun Ng Nor Kamariah Noordin Borhanuddin Mohd Ali Sudhanshu Shekhar Jamuar 《Wireless Personal Communications》2011,58(2):315-335
In code division multiple access (CDMA), two or more chips are grouped together to form symbols and each symbol is transmitted
during the symbol period. The phase shift keying (PSK) modulation techniques map the digital baseband data into two or more
possible signals by varying the phase of a radio frequency (RF) carrier. The recently proposed PSK scheme called ternary PSK
(TPSK) scheme can convey three possible symbols. In this paper, a novel ternary based CDMA sequence so-called large area synchronous
even ternary (LAS-ET) sequence is introduced to increase spectrum efficiency in TPSK scheme. Its sequence duty ratio and cross-correlation
are analyzed. The performance analysis of this sequence is compared with the large area synchronous (LAS) sequence in term
of symbol error rate and chip error rate (CER) over various channel models. It is shown that TPSK scheme in LAS-ET sequence
outperforms LAS sequence in terms of CER evaluation. At the same time, the spectrum efficiency is doubled when a pair of chips
in LAS-ET sequence is mapped into one symbol. 相似文献
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基于扩展二次同余码/单重合序列(EQC/OCS),利用光纤布拉格光栅(FBG)和光纤延迟线作为编解码器,对二维非相干光码分多址(OCDMA)系统进行系统仿真。通过软件仿真,实现了4个用户的EQC/OCS码字的解码相关输出结果。结果表明,低成本的FBG编/解码器实现了EQC/OCS码字的编码和相关解码,提高了二维OCDMA系统容量。 相似文献
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This paper presents a study on dynamic wavelength routed all-optical networks by simulating traffic on all-optical networks. A performance study is carried out on dynamic all-optical networks for fixed and free routing. It is explained how multiple fibers correspond to limited wavelength conversion, and it is explained why the presence of wavelength converters increase the complexity of optical cross connects. We find that both free routing and wavelength conversion lowers the blocking probability significantly. The new contribution is that we determine the gain in blocking probability as function of the number of fibers per link and the offered load. We find that multiple fibers reduce the effect of wavelength converters significantly. 相似文献
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Ying Tan Jian-Zhong Guo Yong Ai 《Photonics Technology Letters, IEEE》2009,21(2):67-69
We propose an iterative coded modulation technique with code rate flexibility for optical space communications. It is a modified version of the existing SCPPM, which consists of the serial concatenation of an outer convolutional code, an interleaver, a bit-accumulator, and pulse-position modulation (PPM), and has been demonstrated to give the best performance on an optical link modeled as PPM/Poisson channels. The primary modification is to add a single-parity-check (SPC) code. We refer to the coded modulation as SPC-SCPPM. The two codes are decoded with an iterative demodulator-decoder, using standard turbo-decoding techniques. We compare the two coded modulation techniques on a PPM/Poisson channel. The rate-1/2 SPC-SCPPM provides performance similar to the SCPPM of the same parameters. However, SPC-SCPPM has been shown to possess code rate flexibility for all rates higher than 1/2 in contrast to SCPPM. 相似文献
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针对大容量多芯光纤空分复用弹性光网络(SDM-EON)中芯间串扰导致业务传输质量下降和阻塞率上升的问题,该文提出了节点稀疏配置频谱转换器降低芯间串扰的路由纤芯频谱分配方法。该方法根据网络中节点中介中心性稀疏配置频谱转换器。在业务路由阶段,设计综合考虑光路负载和节点频谱转换能力的光路选择的权重方法;为了降低串扰,在纤芯频谱分配阶段,设计纤芯分组和频谱分区分配方法;最后,针对串扰较大的业务,采用频谱转换以降低业务串扰和改善带宽阻塞率。仿真结果表明,所提算法能有效地提高频谱利用率,降低因芯间串扰导致的带宽阻塞率。
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