Improved optical coding method for orthogonal ASK/DPSK modulation format

Orthogonal ASK/DPSK labeling, which encodes label information on optical carriers in a modulation format, is regarded as a competing scheme to subcarrier multiplexed optical labeling. However, the inherent cross-talk limits the extinction ratio (ER) of the payload and label sensitivity. In this paper, two optical coding methods-Manchester coding and 8B10B coding-which can remarkably improve the system quality to obtain acceptable ER are discussed. A novel optical packet encoding methodmark-insertion coding-is demonstrated to significantly reduce cross-talk between the amplitude shift keying ASK) payload and the differential phase shift keying (DPSK) label through spectrum shaping. The performance of mark-insertion coding depends on the number of inserted 'marks'. Finally, the transmission over a 40 km single mode fiber (SMF) is compared with optical label swapping for a. 40 Gbit/s ASK payload and 2.5 Gbit/s DPSK label under these coding schemes. The experimental result is consistent with the theoretical analysis.     

无信号内干扰的高效差分混沌键控通信方案

为解决高效差分混沌键控（HE-DCSK）系统判决变量中信号内干扰的不利影响问题,提出一种无信号内干扰的高效差分混沌键控通信方案。该方案通过改变混沌载波的构造方式,确保在相同信息时隙内传输的两路携带不同信息的已调混沌信号严格正交,彻底去除了接收机判决变量中的信号内干扰分量。分析和仿真表明,所提的新系统可以大大改善HE-DCSK系统的误码性能。     

符号内连续相位差分相移键控调制方法

提出了一种幅度准恒包络、相位连续的差分相移键控调制与解调方法.该方法设计了一组基带信号集合,根据输入的信息值和状态值选择基带信号来实现信号调制.在信号解调中,通过计算接收信号在一个符号持续时间内的相位变化累积量来判决发送信息.仿真结果表明,该调制方法具有良好的频谱特性和准恒包络特性,并且避免了本振偏离、多普勒频移等引起的符号间相位变化对信号解调的影响.     

DPSK色散管理孤子系统的稳定传输

DPSK调制方式和色散管理孤子(DMS)传输方案相结合的新的传输机制能抵制噪声和非线性损伤,在高速多通道光传输系统中具有突出优点。采用变分法研究同时存在光纤损耗、ASE噪声、孤子互作用等多种扰动因素的DPSK色散管理孤子系统的传输特性,在频域导频滤波控制方案下,导出了孤子各特征参数随传输距离的演化方程。对40 Gb/s长距离DPSK色散管理孤子系统的传输特性进行了数值模拟,其结果和理论分析一致。并通过Optisystem软件作进一步仿真,论证了该系统零频移稳定传输的可行性。     

一种高速差分混沌移位键控系统

差分混沌键控(DCSK)系统的最大缺点是参考信号和数据信号消耗了相同比例的比特能量和数据传输速率.为了克服这一缺点,提出了一种高速差分混沌键控系统(HR-DCSK).该系统缩短了原来DCSK参考信号的长度,同时数据信号携带2 bit数据,并将数据信号重复发送,提高了数据传输速率和能量效率.推导出在高斯信道中的比特误码率公式并进行仿真,理论分析和仿真表明,在相同信噪比下,HR-DCSK比调频差分混沌键控系统(FM-DCSK)误码率降低了10％.     

一种新型置换相关键控混沌通信系统

在现有的非相干混沌通信系统中,用于传输参考信号的比特能量无法在接收端相关器被恢复出来,因此能量效率不高。针对这一问题,利用混沌序列前、后交换得到的新序列与原序列近似正交的特性,将参考信号与信息调制信号叠加在同一时隙传输,设计了一种置换相关键控混沌通信系统。在加性高斯白噪声信道中,该系统能从接收端相关器恢复全部的发送比特能量,具有比同类方案更高的能量效率。对误码率公式做了理论推导,对噪声性能进行了仿真实验,结果表明,与现有同类非相干混沌通信方案相比该方案具有更低的误码率。     

Design of Amplitude and Phase Modulated Signals for Differential Space-Time Block Codes

A differential space-time block code (DSTBC) provides full diversity advantage and does not require any radio channel estimation in the receiver, which makes it an attractive alternative to the well-known coherent space-time block code (STBC). However the original design of DSTBC allows only pure phase shift keying (M-PSK) modulation scheme, which are not optimal for M > 4. In this paper a simultaneous amplitude and phase modulation scheme for DSTBC with 2 transmit and several receive antennas is introduced. The performance of the proposed scheme is investigated and compared with DSTBC techniques using pure M-PSK modulation. Alexandre Vanaev received B.Eng. degree in Electrical and Electronic engineering from the St. Petersburg State Polytechnic University, Russia in 1998, and M.Sc. degree in “Information and communication systems” from Technical University Hamburg-Harburg in 2002. He is currently pursuing his Ph.D. in the Technical University Hamburg-Harburg, Department of Telecommunications. His research interests include prospective OFDM-based wireless communication systems and MIMO technology. Prof. Hermann Rohling is with the Technical University Hamburg-Harburg, Germany where he has developed an international reputation for Mobile Communication (4G) and automotive radar systems. Previously Prof. Rohling was with the AEG Research Institute, Ulm as a researcher working in the area of digital signal processing for radar and communications applications. His research interests have includedWideband Mobile Communications especially based on Multicarrier Transmission Techniques (OFDM) for future broadband systems (4G), signal theory, digital radar signal processing, detection, estimation and differential GPS for high precision navigation. Prof. Rohling is a member of Informationstechnische Gesellschaft (ITG), German Institute of Navigation (DGON) and a Fellow of IEEE. He is a chairman of the September 2006 International OFDM Workshop (InOWo 2006) and the International Radar Symposium (IRS 2006) in Krakow, Poland. Prof. Rohling is theVice President of the Technical University Hamburg-Harburg.     

Simulation for all-optical format conversion from NRZ-DPSK to RZ-DPSK

We propose and simulate a simple scheme of all-optical format conversion from non-retum-to-zero differential phase-shift keying (NRZ-DPSK) to return-tozero differential phase-shift keying (RZ-DPSK) by using phase modulators and detuning filters.The operation principle is theoretically analyzed and simulated by exploiting spectra,temporal waveform and eye diagram with commerical optical design software VPI Transmission Maker 8.5.The use of electrical clock recovery and linear phase modulation in the conversion scheme may be potiental in practise use.     

An AWG based colorless WDM-PON with RZ-DPSK modulated downstream and re-modulation of DL signal for OOK upstream

We proposed an arrayed waveguide granting (AWG) based 10 Gbps full duplex wavelength division multiplexing passive optical network (WDM-PON) utilizing a retum-to-zero differential phase shift keying (R...     

Performance improvement of bandwidth-limited coherent OCDMA system

The performance of an optical code division multiplexing access (OCDMA) system employing the differential phase shift keying (DPSK) data format and turbo code is investigated and simulated. A bandwidth-limited coherent time spreading (TS) OCDMA system is considered. Theoretical results show that performance degradation due to bandwidth limitation could be effectively restrained by the application of the DPSK data format in a coherent OCDMA system, and further performance improvement could be achieved by incorporating turbo coding into the OCDMA system.

Computing the Average Symbol Error Probability of the MPSK System Having Quadrature Error

When quadrature error exists, the shape of the M‐ary phase shift keying (MPSK) signal constellation becomes skewed‐elliptic. Each MPSK symbol takes on a different symbol error probability (SEP) value. The analytical results presented thus far have been derived from studies which examined the SEP problem assuming that the SEP of each MPSK symbol is equally likely; therefore, those results should not be treated as offering a complete solution. In this letter, we present a new and more complete solution to the SEP problem of MPSK by relaxing the above assumption and finding the expressions for the average as well as individual SEP in the presence of quadrature error.     

RZ-DPSK传输系统相位噪声的比较分析

建立了单信道40Gbit／s归零-差分相移键控码（RZ-DPSK）传输系统模型,详细地分析并比较了线性相位噪声和非线性相位噪声对系统性能的影响。结果表明,由放大器自发辐射（ASE）噪声带来的线性相位噪声对传输系统的性能影响最大,ASE与自相位调制（SPM）相互作用引起的Gordon-Mollenauer（G-M）相移次之,带内四波混频（IFWM）的影响最小。在最优输入功率的条件下,由ASE带来的线性相位噪声引起的系统差分相位Q值代价大于204dB,由G-M相移引起的系统差分相位Q值代价小于7．5dB。仿真结果表明,对于采用掺铒光纤放大器（EDFA）级联放大的单信道40Gbit／s RZ-DPSK传输系统,ASE噪声是限制系统无中继传输距离的最主要因素。     

fso中一种光载波外差dpsk系统的设计

介绍了自由空间光通信中的相干通信系统,通过对相干光通信中振幅键控(ASK),频移键控(FSK),相移键控(PSK),差分相移键控(DPSK)四种光载波相干调制方式性能的分析和比较,仿真结果得出PSK调制误码性能更好,提出了一种光载波外差差分相移键控(DPSK)系统.     

基于仿真软件的DPSK光纤传输性能研究

介绍了DPSK码型的产生原理,通过仿真软件模拟级联调制器产生各种DPSK光调制码型,给出了频谱,并基于仿真软件建立了DPSK光纤传输模型,重点考虑了光放大器的自发辐射(ASE)噪声对DPSK系统的性能影响.实际仿真结果表明了ASE噪声是限制级联DPSK传输系统传输距离的最主要因素.     

基于改进的差分混沌键控（DCSK）保密系统

差分混沌键控(differential chaos shift keying,DCSK)利用了混沌信号类噪声的特性,采用非相干接收,避免了混沌同步问题。针对DCSK的保密性问题,提出一种改进的DCSK方案,通过仿真验证该方案的可行性,并对其性能进行深入分析。结论:改进的DCSK系统与传统的DCSK系统相比,误码率更低,保密性也更好。     

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。     

卫星通信中连续相位QPSK调制的带宽效率分析

连续相位调制(CPM)是一种带宽效率很高的调制技术,适用于卫星非线性信道。在将正交相移键控(QPSK)表示成CPM的基础上,提出了一种基于离散傅里叶变换(DFT)的谱密度计算公式。利用MATLAB的快速傅里叶变换(FFT)运算仿真了连续相位QPSK(CPQPSK)的功率谱,结果表明CPQPSK较QPSK具有更高的带宽效率。