共查询到15条相似文献,搜索用时 140 毫秒
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波分复用OCDMA系统的性能分析 总被引:6,自引:5,他引:1
分析了波分复用(WDM)光码分多址(OCDMA)系统的归一吞吐量性能。当同时用户数均匀分配到不同的波长时,得到了WDM OCDMA系统归一化吞吐量性能的上界;当同时用户数尽量分配到同一个波长时,得到了WDM OCDMA系统归一化吞吐量性能的下界。在所有用户均匀分配到不同波长信道的条件下,比较了WDM OCDMA与多波长(MW)OCDMA系统的归一化吞吐量性能。结果表明,当负载较小时,两者的性能基本相当;当负载较大时,WDM 0CDMA的性能优于MW OCDMA系统。同时,WDM OCDMA的归一化吞吐量峰值高于MW OCDMA系统的归一化吞吐量峰值。 相似文献
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基于光正交码,研究了WDM+OCDMA系统的性能。采用4个波长信道和3个码字的光正交码OOC(37,4,1),对12个用户的WDMA+OCDMA进行了系统仿真,用户数据速率为1Gbit/s,单模光纤长为50km,色散补偿光纤长为5km。如需增加WDMA+OCDMA的用户数,可以通过增加波长信道数或码字容量来实现。分析了色散效应对WDMA+OCDMA系统性能的影响,研究了用户之间相对延时对多址干扰和系统性能的影响。 相似文献
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采用光硬限幅器和RS码的多波长OCDMA性能分析 总被引:1,自引:1,他引:0
提出了一种采用多个光硬限幅器和RS信道编码的多波长光码多分址(MW OCDMA)系统,理论分析了其误码率和(BER)和归一化吞吐量性能.结果表明,采用光硬限幅器的MW OCDMA系统BER性能将明显改善,进一步采用RS信道编码后,MW OCDMA系统BER性能将大大改善.另一方面,采用光硬限幅器的MW OCDMA系统的归一化吞吐量明显提高,特别是归一化吞吐量峰值提高了约1倍,但进一步采用RS信道编码后,MW OCDMA系统的归一化吞吐量并没有提高,在系统负载量不是很大的情况下还略有下降. 相似文献
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在马纳可夫偏振分集(Manakov PDM)系统中采用偏振分集技术令光脉冲沿着两个正交极化方向传输,能够克服光脉冲的相互干涉,提高通信系统的传输速率.当光脉冲为超短脉冲双曲型孤子时,偏振分集系统就需考虑三阶色散和Kerr色散效应的影响,脉冲的包络满足改进的Manakov耦合方程.高阶色散效应中孤子的相干性可以利用拉格朗日6agrange)方法和微扰理论进行研究. 相似文献
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光码分多址(OCDMA)系统的误码率是评价系统性能的重要指标,由于色散和非线性效应会导致超短光脉冲在光纤传输过程中脉宽的展宽,进而影响OCDMA系统的误码率。在基于理想情况的OCDMA系统误码率定义的基础上,研究了三阶色散和三阶非线性效应对系统误码率的影响,进一步分析了有硬限幅器和二维OCDMA系统的误码率。结果表明,三阶色散和三阶非线性效应都会导致OCDMA系统误码率的增大,但三阶非线性效应对系统性能影响没有三阶色散效应明显;在系统参数相同基础上,接收端引入光硬限幅器和系统采用二维编码均可优化系统性能。 相似文献
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首先分析了基于载波抑制归零码的光载波抑制归零-开关键控(CSRZ-OOK)、载波抑制归零-差分相移键控(CSRZ-DPSK)和载波抑制归零-差分正交相移键控(CSRZ-DQPSK) 三种光调制格式的时域和频域特性,并数字仿真了其在40 Gbit/s单信道光纤系统中的传输性能.以Q值、眼图和误码率(BER)作为性能评价指标,研究了这三种调制格式对色散(CD)、偏振模色散(PMD)和非线性效应的抑制作用.结果表明:CSRZ-DQPSK相对于CSRZ-OOK、CSRZ-DPSK对色散、偏振模色散和非线性效应有非常好的容忍能力. 相似文献
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在160Gb/s光时分复用(OTDM)系统中,带内四波混频(IFWM)效应是影响系统性能的因素之一。分析了IFWM效应对160Gb/s光时分复用传输系统性能的影响,对采用强色散管理的方法抑制IFWM效应进行了理论分析和实验验证。传输链路采用大色散斜率的标准单模光纤(SSMF)和色散、色散斜率补偿光纤混合的色散管理方式,能够很好地抑制"1"比特处的脉冲幅度变化和"0"比特处产生的寄生脉冲,提升系统的整体性能。在不需要前向纠错和功率代价小于3.6dB的条件下,实现了较长时间(时间大于2h)的无误码(误码率小于10-12)传输。 相似文献
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As the wavelength resource in mainstream wavelength-division multiple-access (WDMA) systems becomes exhausted, and the bit-rate limitation within a single wavelength bandwidth is reached, alternative approaches to implementing a high-capacity optical fiber network need to be investigated. Coherent optical code-division multiple-access (OCDMA) systems, that can access many users simultaneously and asynchronously (or synchronously) across the single wavelength and same timeslot via spread spectrum techniques, are one alternative. In the longer term, the advantages of OCDMA in tandem with WDMA (OCDMA/WDMA) networks are compelling and worthy of further investigation in the goal of realising an extensive, flexible, high throughput and easily managed optical telecommunication infrastructure. In this paper, coherent OCDMA systems are introduced, and the issues of the system implementation within high-capacity optical fiber networks are discussed. A performance comparison between OCDMA and OTDMA systems is then carried out, both of them using narrow pulse laser sources. An optical fiber network utilizing coherent OCDMA techniques as one layer of a multiplexing hierarchy, in tandem with WDMA, is illustrated and a possible hybrid OCDMA/WDMA network architecture (and its performances and advantages) is described 相似文献
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The performance of optical code-division multiple-access (CDMA) systems with wavelength-hopping/time-spreading codes is compared to that of a wavelength-division multiple-access (WDMA) system. The multiple-access techniques are applied in a time-slotted broadcast local area network. The utilization, defined as the throughput per unit of time-domain bandwidth expansion, and packet delay are used as metrics of performance. When more than seven wavelengths are available, optical CDMA systems using asymmetric prime-hop codes and all-optical signal processing are shown to have higher peak utilization and lower corresponding delay than a WDMA system with the same number of wavelengths. When the encoders/decoders operate at the chip rate, the utilization of optical CDMA exceeds that of WDMA at high offered loads; however, the peak utilization of the WDMA system is still superior. 相似文献
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JI Jian-hua XU Ming YANG Shu-wen ZHANG Zhi-peng 《光电子快报》2006,2(1):55-57
Recently,because of advantages of high-speed opticalprocessing and si mple network control ,the optical codedivision multiple access (OCDMA) has become a hotscheme in LAN and access network[1-5]. According tothe spreading mode, OCDMAcan be mainly dividedi… 相似文献
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We compare the theoretical bit-error-rate (BER) and throughput performance of asynchronous time-spreading (TS) phase coding
and two-dimensional (2D) wavelength-time (WT) optical code division multiple access (OCDMA) communication systems. Particular
consideration is given, however, to both beat noise (BN) and multiple access interference (MAI) effects. BER performance of
the TS OCDMA scheme is much superior to that of the WT scheme in the MAI limited case, while the WT scheme has better tolerance
to beat noise. Improvement of BER performance and throughput can be obtained by utilization of optimum threshold detection.
The two OCDMA schemes have comparable bit-error probability, and the WT scheme achieves a higher throughput for a heavy load
when the optimum threshold is employed. 相似文献
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Chao Zuo Wenhua Ma Hongtu Pu Jintong Lin 《Lightwave Technology, Journal of》2001,19(10):1416-1419
In this paper, we develop a systematic method that employs transfer function considering encoder, fiber channel, and decoder to analyze the frequency-hopping (FH) optical code-division multiple-access (OCDMA) system. We analyze the FH-OCDMA system when both single-mode fiber and dispersion-shifted fiber are employed as the transmission medium. The difference of group velocities affects system performance more seriously than dispersion effect does. The results show that single-mode fiber is not proper for a FH-OCDMA system, even if the transmission length is no more than 1 km. The dispersion-shifted fiber is suitable for a FH-OCDMA system, especially in an access network. We also propose an optical device to compensate the group velocities 相似文献