Optical Systems With High-Order DPSK and Star QAM Modulation Based on Interferometric Direct Detection

Increased interest in novel modulation formats for optical transmission has come up in recent years. Receivers with interferometric direct detection can be used to detect arbitrary modulation formats with differentially encoded phases as differential phase-shift keying (DPSK) and differentially phase-encoded star-shaped quadrature amplitude modulation (Star QAM). In this paper, two novel 16-ary modulation formats, which are the 16 DPSK and the Star 16 QAM (ASK-8 DPSK), are characterized for optical transmission for the first time. To be able to identify clear performance tendencies for high-order optical modulation, the novel formats are compared to a wide range of already investigated formats by conducting comprehensive calculations in a uniform simulation environment. The influence of different transmitter structures and decision schemes is considered, and all the systems are characterized with respect to the optical signal-to-noise ratio requirements, dispersion tolerance, and self-phase-modulation (SPM) performance for nonreturn-to-zero (NRZ) and RZ pulse shapes. Moreover, an inherent problem of Star QAM transmission concerning SPM is illustrated, and compensation techniques are examined. The results give a substantial insight into the properties of high-order optical modulation formats.     

2DPSK光纤通信系统的误码特性分析

通过把噪声展成KLSE级数的方法,得到了2DPSK光纤通信系统接收端噪声以及抽样判决变量的概率分布特性.在此基础上分析了2DPSK光纤通信系统的抗噪声特性.经过蒙特卡洛仿真验证可知,把KLSE方法用于2DPSK光纤通信系统是完全可行的.分析了2DPSK光纤通信和OOK光纤通信系统的抗噪性能,得出在同样误码率情况下2DPSK系统所需信噪比的值比OOK系统低3 dB的结论.     

Performance Evaluation of QAM for Improvement of BER

Wireless Personal Communications - This paper presents performance evaluation of the mary quadrature amplitude modulation (M-QAM). BER performance is evaluated on operation of The Binary coding,...     

TD—LTE QAM仿真和误码率性能研究

从调制解调原理出发,通过MATLAB仿真较为全面地分析了16QAM和64QAM这两种基带调制解调技术,比较了它们之间的区别,并研究了高斯和瑞利信道的理论特征、产生过程以及对通信信道的影响,讨论了QAM经过高斯和瑞利信道后的误码情况,分析了这两种QAM在同样信道路条件下的误码率,总结了0AM调制过程中的相关技术,可为今后应用更高阶QAM调制方式提供理论参考。     

在AWGN信道下星形MQAM的BER性能的研究

本文采用一种新型的信号空间轴线分析方法,根据星型MQAM信号星座在信号空间中的排列方式,将其看作为ASK与PSK的综合,从而得到了加性高斯白噪声（AWGN）信道下星型MQAM的误比特率(BER)性能的通用近似公式,蒙特-卡洛仿真结果表明其理论分析值与实际系统基本相符。     

A Tight BER Upper Bound for Bit-Interleaved Coded Modulation with Square QAM and Gray Labeling

Bit-interleaved coded modulation (BICM) is a bandwidth-efficient coded system with diversity order higher than that of Ungerboeck's trellis-coded modulation on fading channels. In this paper, we investigate the BER (bit error rate) performance of BICM in the additive white Gaussian and Rayleigh fading channels. A new upper bound is given for the square QAM constellation with gray labeling, which constitutes a large portion of practical applications of BICM systems. The new upper bound is tighter than the well-known BICM union bound proposed in G. Caire et al. (1998)     

Pulse-Position Modulation for Transmission Over Optical Fibers with Direct or Heterodyne Detection

The best monomode optical fiber links have bandwidths orders of magnitude greater than that of the information currently transmitted over them. This excess bandwidth can be exploited using digital PPM to improve receiver sensitivity. This paper analyzes the receiver sensitivity of an optical PPM system over a slightly dispersive channel, i.e., where both "wrong slot" and "false alarm" errors are important. It is shown that receiver sensitivity of better than 100 photons per binary bit-time is theoretically possible using direct detection and uncoded PPM. Ideal heterodyne detection should reduce this to below 5 photons per binary bit-time. Timing extraction and a digital modulation method are discussed.     

各向异性海洋湍流对外差式DPSK无线光通信系统的性能研究

应用广义的惠更斯-菲涅耳原理及改进的Rytov方法,采用基于Gamma-Gamma光强概率分布的海洋湍流信道模型,得到了中断概率解析式.并在此基础上对各向异性海洋湍流高斯光束外差式差分相移键控(DPSK)调制的中断概率性能进行了研究.仿真分析了不同的各向异性海洋湍流下各种海洋湍流参数(温度与盐度波动对功率谱变化贡献之比...     

一种降低光纤通信系统误码率的方法

针对光纤通信系统在传输过程中易受光纤线路、传输设备等因素干扰的问题,提出了一种利用基于卷积神经网络的编码器-解码器来降低接收端信号误码率的方法,从而提升光纤通信系统的抗干扰能力。具体地,利用伪随机二进制序列(Pseudo-Random Binary Sequence)码作为标签信号,将受干扰后的信号作为输入信号,训练出具有恢复受扰信号能力的卷积编码器-解码器。实验结果表明,卷积编码器-解码器能降低受一定程度干扰的信号误码率,具备提升光纤通信系统抗干扰性能的能力。     

Nearly Shot-Noise-Limited Performance of Dual-Channel Linear Optical Sampling for Ultrafast DPSK Signals

This paper describes a newly developed dual-channel linear optical sampling technique for observing ultrafast optical differential phase-shift keying (DPSK) signals. As the proposed measurement scheme offsets two parallel interferometers by a relative delay corresponding to 1-symbol length of the DPSK signal, the measured phase distribution reflects the signal quality which is determined by the phase difference between adjacent symbols. This technique, based on interferometric optical gating by local short-pulses, also offers ultrafast measurement at symbol rates of greater than 100 Gsymbol/s. Moreover, its detection sensitivity can reach the shot noise limit. The waveform degradation caused by the coherence of the light source and the pattern effect of the phase modulator is successfully observed in continuous waves and 10-Gsymbol/s nonreturn-to-zero DPSK signals, and the constellation measurement is demonstrated for a 160-Gsymbol/s return-to-zero DPSK signal. Measurement system noise is also discussed for characterizing the detection sensitivity, and the nearly shot-noise-limited performance is experimentally verified.      

基于SIMULINK的16QAM基带调制系统性能仿真

移动通信的物理层采用的调制方式主要有BPSK、QPSK、16PSK、16QAM等自适应数字调制解调技术。本文通过对信源产生的数字信号,经过16QAM调制解调方式对信号进行调制。通过对误码率的测试比较,来分析16QAM调制解调方式的性能。     

DPSK/FSK Hybrid Modulation Format and Analysis of Its Nonlinear Performance

We propose a novel hybrid modulation format-differential phase shift keying with frequency shift keying labeling for optical label switching. A modulation technique based on a dual-parallel Mach-Zehnder modulator and a label erasing scheme are presented. The tolerance of the new format to intrachannel four-wave mixing at high speeds is studied analytically and through simulations, which show robustness to nonlinear impairments.     

频域扩频码片级差分检测的误码率性能分析

该文提出了一种频域扩频系统中的差分检测方法:频域扩频码片级差分检测.通过利用判决变量的矩生成函数,并采用鞍点近似的分析方法,得到了频域扩频码片级差分检测的误码率性能的解析表达式,同时进行了仿真验证.分析和仿真结果表明,频域扩频码片级差分检测具有抵抗频率选择性衰落的能力,在信道的相干带宽不小于两个码片对应的频带宽度的前提下,随着信道多径时延扩展的增加,其误码率性能有进一步的提高.     

A Novel Direct Detection Microwave Photonic Vector Modulation Scheme for Radio-Over-Fiber System

This letter demonstrates the feasibility of a novel direct detection microwave photonic vector modulation scheme for the radio-over-fiber (RoF) system. Unlike the traditional double-sideband with optical carrier suppression modulation scheme, which can carry only the on-off keying data format, the proposed scheme encodes the electrical vector signal on either the upper sideband (USB) or the lower sideband (LSB) only and a pure optical subcarrier on the other sideband. Therefore, phase and amplitude information will be preserved after direct detection. A frequency doubling scheme is employed to reduce the cost of RoF systems. Additionally, the relative intensity between USB and LSB can be easily tuned by adjusting the individual power of electrical driving signals to optimize the performance of the optical radio-frequency signals. A proof-of-concept experiment is conducted by using a 1.25 Gb/s BPSK signal at a carrier frequency of 20 GHz. After transmission over 50-km single-mode fiber, the receiver sensitivity penalty is less than 0.5 dB.     

非正交多脉冲通信系统的多用户检测性能分析

随着多用户检测技术研究的深入,对非正交多脉冲调制(NMM)信号的接收机的设计是非常必要的。针对非正交多脉冲调制信号多用户干扰问题,设计了一种非相干解相关接收机前端,这种接收机将多用户信道分解成K个单用户信道,这样相当于将多用户检测问题转换成噪声加强的单用户检测问题,极大地降低了问题的复杂性。仿真结果表明了此检测算法的性能优于常规检测器。     

BER performance with soft and hard decision decoder for coherentoptical DPSK systems corrupted by phase noise

The performance of coherent optical communication systems is significantly degraded by semiconductor laser phase noise. A rate 1/2, constraint length K=7, convolutional error correcting code with Viterbi decoding is used to improve a 3.5-10 Mbit/s DPSK system. Error correcting coding demonstrates the reduction of the influence of phase noise on BER performance, and significantly lowers the BER floor. Soft decision decoding and hard decision decoding performance is investigated and compared     

无线光自适应副载波MDPSK调制系统特性分析

无线光通信中的自适应传输技术可有效抑制大气湍流引起的信道衰落.根据接收信噪比和预定目标误比特率要求,本文对通过瞬时湍流特性改变调制阶数的无线光自适应传输的通信系统进行了研究.给出采用Malaga分布湍流模型分别描述Gamma-Gamma、对数正态以及K分布湍流信道的相关参数设置;推导了Malaga湍流信道下无线光自适应多进制差分相移键控（MDPSK,M-ary Differential Phase Shift Keying）调制系统的平均误比特率、频谱效率以及中断概率表达式,以及基于MeijerG函数的渐近表达式.MDPSK自适应和非自适应两种调制系统特性分析结果表明：自适应调制系统不但在相同电信噪比下可获得更低的平均误比特率,还可以大大提高频谱效率,而不需要增加额外传输功率或牺牲误比特率.     

星间光通信振动对系统性能的影响--直接检测PPM调制方式

星间光通信中振动是影响系统性能的重要因素，即使其中一个卫星的瞄准系统的很小幅度的振动也可以引起整个网络的性能急剧恶化。分析了直接检测脉位调制（PPM）下振动对网络性能的影响。     

无线光通信调制方式性能分析

无线光通信的调制方式有多种,但缺少综合系统的分析。在详细地分析了脉冲位置调制（PPM）、数字脉冲间隔调制（DPIM）和双头脉冲间隔调制（DH—PIM）等调制方式符号结构的基础上,比较了各种凋制方式的平均发射功率和带宽效率,并在给定模型下分析了误时隙率。通过分析得出DPIM和DH—PIM更具有优势,更适合于未来无线光通信系统。     

BER Performance of NRZ-OOK and Manchester Modulation in Indoor Wireless Infrared Links

This paper describes a novel approach to theevaluation of the bit error rate (BER) performance ofoptical wireless links that takes into account shotnoise, fluorescent light interference, and intersymbol interference (ISI) from both multipathdispersion and high-pass filtering (HPF) at thereceiver. The calculation of the BER is achieved withthe use of an efficient numerical technique based onnonclassical Gauss Quadrature Rules. Fluorescent lightinterference is modeled as a Fourier series expansionwith coefficients taken from measurements, whilemultipath-induced ISI is calculated by using previouslyreported IR channel models. Application of the techniquepresented here allows for the calculation of the optimumHPF cutoff frequency that minimizes the overallperformance penalty. Finally, as an application of this method, the BER performance of NRZ-OOK andManchester (2-PPM) modulation is evaluated and numericalresults are presented for different linkscenarios.