光DQPSK调制原理

光DQPSK作为一种新型光纤通信系统的调制格式，具有非常窄的频谱宽度，近似恒定的包络特性，能有效抑制各类光纤的非线性效应。从它的基本原理推导入手，分析了光DQPSK编码，调制和解码过程，提出了实现光DQPSK调制的两种方式和接收模型。     

光DQPSK调制原理

光DQPSK作为一种新型光纤通信系统的调制格式,具有非常窄的频谱宽度,近似恒定的包络特性,能有效抑制各类光纤的非线性效应。从它的基本原理推导入手,分析了光DQPSK编码,调制和解码过程,提出了实现光DQPSK调制的两种方式和接收模型。     

光DQPSK调制格式原理及仿真

文章简单介绍了光差分正交相移键控(DQPSK)调制格式的调制和解调方式,对光DQPSK的预编码也进行了必要的说明.使用软件Matlab构建了光DQPSK背靠背系统,得到了不同的DQPSK调制的频谱图和眼图,并对仿真结果进行了验证,就NRZ-DQPSK和RZ33-DQPSK的差异进行了比较.     

光纤通信系统中两种新型调制格式的比较

给出了光差分正交相移键控(DQPSK)和光八差分相移键控(8DPSK)调制格式的调制和解调方式,并用Matlab仿真得到了DQPSK和8DPSK调制的NRZ、RZ33和CSRZ系统的频谱图以及解调后的眼图.结果表明,DQPSK和8DPSK作为新型调制格式,具有更窄的频谱宽度、更高的频谱效率,经传输后的眼图性能也很好.     

100Gb/s RZ-ODQPSK实现方法性能比较

光差分正交移相键控(0DQPSK)调制格式在高速光纤通信系统中有着巨大的应用潜力.文章给出了高速0DQPSK调制格式的三种实现方式(串联调制、并联调制和双驱动单调制器调制),在建立仿真模型的基础上,对光信噪比(0SNR)、色散、偏振模色散(PMD)以及光纤非线性四个方面的容纳能力进行了对比、分析和研究.     

LDPC编码的空时BICM系统中的一种优化设计方案

本文基于外附信息转移(EXIT)图的系统优化设计思想,提出了一种级联预编码器的低密度奇偶校验码(LDPC)编码的空时比特交织编码调制(BICM-MIMO)系统设计方案.该方案在调制器的前端级联一个码率为1的累加器作为预编码器,在相邻的比特之间引入相关性,从而使得联合检测器的EXIT曲线发生变化,与空时MIMO系统下优化LDPC码的译码器EXIT曲线相匹配,并使两条曲线相交于EXIT图的右上角.和已有系统设计方案相比,该方案可提高系统的译码性能并能降低误码的错误平层(error floor).     

具有线性星座预编码的差分空频码

针对传统差分空频码中常模调制符号限制系统编码增益提高的问题,提出具有线性星座预编码的差分空频码.它增大差分空频码字的最小乘积距离,提高系统编码增益.描述了线性星座预编码器的设计原则和设计方法.介绍了归一化差分调制和差分译码.通过对系统平均成对符号误码性能分析,从理论上给出相对传统差分空频码提高的编码增益.仿真实验结果也说明提出的差分空频码能够获取满分集和较大的编码增益.     

OWC中DPPM调制解调技术研究

调制解调技术一直是光无线通信(OWC)领域中的研究热点之一.较之脉冲位置调制(PPM),差分脉冲位置调制(DPPM)是一种光功率利用率和带宽利用率都较高的调制方式.本文对PPM调制和DPPM调制进行了比较分析,提出了基于FPGA的DPPM调制解调系统的设计方案.硬件仿真结果表明,该系统性能稳定,可以应用到光无线通信系统中.     

光8DPSK调制原理及仿真

光8DPSK(optical Differential 8-Phase Shift Keying)是一种多级相位调制新码型,是光通信领域研究的前沿,文章介绍了光8DPSK调制格式原理和调制解调方式,用Matlab做了仿真,绘制出了频谱图、眼图,并对占空比为0.5的RZ-8DPSK信号做了详细分析,调制和解调了64个伪随机码序列,仿真绘制了光脉冲时序图、相位差图和平衡接收后的电信号时序图.     

差分空间调制中的非恒模调制方法

差分空间调制(DSM)由于不依靠信道状态信息(CSI)而备受关注.传统的DSM采用了恒模调制的方法,例如相移键控(PSK),但是在高速传输时PSK对星座图的空间自由度利用很低.针对该问题提出了一种DSM系统中的非恒模调制方法,通过对发射信号做相关预编码处理,使之消除非恒模调制在DSM系统中存在的幅度迭代问题.除此之外,为了使之可以体现分集增益,通过减小传输速率来达到满分集增益,并且加入一个功率均衡项来使该系统可以利用非恒模调制.仿真结果表明所提算法随着信噪比的提高,性能会逐渐优于PSK.     

Implementation of area optimization precoder in a 40 Gb/s PolDM-DQPSK system

In this paper, a new model based on an improved Brent Kung (BK) parallel prefix network (PPN) algorithm is proposed and realized in the field programmable gate array (FPGA). This model is employed in the implementation of 20 Gb/s differential quadrature phase-shift keying (DQPSK) precoder in 40 Gb/s polarization division multiplex (PolDM) DQPSK system. In the computation process, the computation complexity (area) optimization with fan-out limited is achieved. In the implementation, 770 FPGA slice registers are utilized, which save about 60% logic resources compared with the previous Kogge Stone (KS) algorithm.     

Transmission Performance Comparison of Direction Detection‐Based 100‐Gb/s Modulation Formats for Metro Area Optical Networks

Transmission performances of direct detection‐based 100‐Gb/s modulation formats are investigated and compared for metro area optical networks. The effects of optical signal‐to‐noise ratio sensitivity, chromatic dispersion, cross‐channel nonlinearity, and transmission distance on the performance of differential 8‐ary phase‐shift keying (D8PSK), differential phase‐shift keying plus three‐level amplitude‐shift keying (DPSK+3ASK), and dual‐carrier differential quaternary phase‐shift keying (DC‐DQPSK) are evaluated. The performance of coherent dual‐polarization quadrature phase‐shift keying (DP‐QPSK) with block phase estimation and coherent DP‐QPSK with digital differential detection are also presented for reference. According to our analysis, all three direct detection modulation formats could transmit a 100‐Gb/s signal over several hundred kilometers of a single‐mode fiber link. The results also show that DC‐DQPSK outperforms D8PSK and DPSK+3ASK, and the performance of DC‐DQPSK is comparable to that of coherent DP‐QPSK with digital differential detection. The maximum transmission distance of DC‐DQPSK is over 1,000 km, which is enough distance for metro applications.     

Design of New SAW DQPSK Matched Filter

A new surface acoustic Wave differential quadraphase shift key（SAW DQPSK） spread spectrum （SS） signal matched filter based on the fusion of SS and differential modulation is reported. The design of multi-phase coded SAW matched filter is proposed rather than another design of SAW DQPSK filter, which can cut in a half of the delay time of SAW DQPSK matched filter and SAW fixed delay line（FDL） used for differential demodulation. This breakthrough is made the system largely reduce a size and process much easily. This method can also be feasible in other SAW MPSK matched filter design especially when the modulation phase number is larger than 4. The design example and its experimental results are given.     

基于晶体延迟干涉仪的20-Gb/sNRZ-DQPSK解调实验研究

光差分四相移键控(DQPSK)信号解调技术是相位调制光纤通信系统中的关键技术,本文利用钒酸钇(YVO4)晶体设计制作了2 bit延迟干涉仪(DI)作为DQPSK解调器。相对于传统的基于光纤结构的DI,用晶体材料制作的DI具有温度稳定性高的特点,其作为光DQPSK解调技术中的关键器件,具有广泛的应用前景。实验搭建了20 Gb/s光NRZ-DQPSK背靠背实验系统,并利用自主设计制作的DI成功实现了NRZ-DQPSK信号解调。实验结果与计算机仿真计算结果一致。     

D8PSK调制格式研究及其传输性能分析

研究了基于相位调制原理的新型调制格式差分八相相移键控(D8PSK),给出了串联和并联两种信号生成方案,对包括非归零码(NRZ)、33%占空比归零码(33%RZ)、50%占空比归零码(50%RZ)、载波抑制归零码(CSRZ)4种不同码型的生成方式进行了说明,对信号的接收过程和预编码公式进行了理论推导,并对系统进行了仿真。仿真系统中信号总速率达到100 Gbit/s,信号生成采用串联方式,信号接收采用4个马赫-曾德尔时延干涉仪(MZI)平衡检测接收机,色散补偿方式采用对称补偿,通过眼图可以看到其接收效果良好。最后对不同码型的D8PSK与DQPSK系统在抵抗群速度色散效应、非线性效应及偏振模色散效应3种主要影响系统传输性能的因素方面进行了分析比较。当眼图张开度代价为1dB时,CSRZ-D8PSK信号的群速度色散容限、非线性容限及偏振模色散容限分别为190ps/nm、4.4 dBm及24 ps,结果表明其具有较好的传输性能。     

OSNR Monitoring Technique for DPSK/DQPSK Signals Based on Self-Heterodyne Detection

We describe a new method for monitoring the “in-band” optical signal-to-noise ratio (OSNR) of differential phase-shift-keying (DPSK) and differential quadrature phase-shift-keying (DQPSK) signals. This technique estimates the OSNR by analyzing the radio frequency spectrum obtained by the self-heterodyne detection. The results show that the performance of the proposed technique is not sensitive to the effects of chromatic dispersion and polarization-mode dispersion. In addition, this technique can be used for monitoring the polarization-scrambled signals. For a demonstration, we measure the OSNR of the polarization-scrambled 10-Gb/s DPSK and 20-Gb/s DQPSK signals in a 640-km-long transmission link.      

基于马赫-曾德尔调制器的先进调制格式的产生

提出了一种基于差分马赫-曾德尔调制器(MZM)产生80 Gbit/s高速率差分相移键控归零码(RZ-DPSK)、差分相移键控载波抑制归零码(CSRZ-DPSK)、差分正交相移键控归零码(RZ-DQPSK)、差分正交相移键控载波抑制归零码(CSRZ-DQPSK)的新方法.在采用两个差分MZM级联产生数据速率为80 Gbit/s的RZ/CSRZ-DPSK光信号的基础上,仅需增加一个双驱动MZM,就可以产生RZ/CSRZ-DQPSK信号,说明提出的方法有一定的扩展性,并简化了高速RZ/CSRZ-DQPSK光信号的产生过程.对产生的80 Gbit/s RZ/CSRZ-DPSK和RZ/CSRZ-DQPSK信号进行的仿真结果表明,CSRZ-DPSK信号比RZ-DPSK信号的频谱结构更加紧凑,差分正交相移键控(DQPSK)光谱形状与差分相移键控(DPSK)相同,只是由于RZ/CSRZ-DQPSK在码元速率下传输数据,得到的光谱在频域被压缩.     

Performance evaluation of optical DQPSK using saddle point approximation

In this paper, the authors derive the moment generating function (MGF) of the decision variable for a practical optical differential quadrature phase shift keying (DQPSK) receiver affected by phase noise and the amplifier spontaneous emission noise. The effect of the different optical filters, Gaussian, Fabry-Pe/spl acute/rot (FP), and optical integrator, on the phase noise is examined. Using the saddle point approximation, the authors obtain numerically the bit error rate (BER) for the above system, as a function of the optical-signal-to-noise ratio (OSNR) and the source linewidth. The model is found to agree with previous published simulation results and the Monte Carlo simulations presented in this paper. The authors also calculate the BER floors for DQPSK inflicted by the phase noise and compare its performance with differential phase shift keying (DPSK). Finally, the authors examine the effect of interferometric demodulation on the relative intensity noise (RIN) spectra and the impact on the DQPSK system performance. In particular, the authors examine the influence of system dispersion on the receiver sensitivity.     

基于MZM的RZ/CSRZ-DQPSK信号产生的新方法

差分相移键控(DPSK)和差分正交相移键控(DQPSK)对光纤非线性具有很高的容忍度,且灵敏度高,在高速、高频谱效率系统中具有优越性。提出了一种基于双驱动马赫-曾德尔调制器(MZM)的差分正交相移键控归零码(RZ-DQPSK)和差分正交相移键控载波抑制归零码(CSRZ-DQPSK)信号产生的新方法。利用一个双驱动MZM实现DQPSK调制,另一个MZM实现波形切割,生成RZ/CSRZ-DQPSK信号。给出了详细的理论推导过程。该方法简化了高速RZ/CSRZ-DQPSK光信号的产生过程,减少了调制器个数。仿真结果表明,CSRZ-DQPSK信号载波频率分量被抑制,具有比RZ-DQPSK信号更紧凑的频谱结构,采用平衡相干检测接收方法接收到的信号有清晰的眼图。