基于极化状态—幅度—相位调制的高效无线传输方案

针对双极化通信场景下正交极化信号串扰导致的解调性能恶化问题,提出了一种基于正交向量的极化相关衰减效应消除方法. 该方法通过对发送信号进行设计,利用一组正交向量分别在发射端和接收端对极化信号进行处理,达到消除极化间串扰的目的,同时在发送端利用估计的信道参数处理发送信号,进一步消除非理想信道影响. 在不改变噪声功率的基础上,实现正交极化信号的无串扰接收,有效提高接收端信号解调性能. 理论分析和仿真结果表明,极化状态调制信号的解调误码率逼近高斯信道下的理论值,相比于预补偿方法和迫零矩阵法有更好的误码率性能,仿真结果与理论推导具有较好的一致性. 本文方法能有效解决无线信道中正交极化信号间串扰,提高接收端信号解调性能.     

一种自适应正交虚拟极化抗主瓣干扰方法研究

提出了基于自适应的正交虚拟极化干扰抑制算法。采用垂直与水平双极化数字阵对该自适应抗主瓣干扰算法进行了验证研究。实验结果表明,所给出的算法可以取得大于20 dB的干扰抑制比,性能与传统的单凹口极化滤波器二维搜索算法相当,而计算量减少了上万倍,具有良好的工程应用前景。     

基于极化椭圆参数的零导数正交搜索最优极化方法

针对基于极化椭圆参数的信干噪比参量等式,提出一种基于极化椭圆参数的零导数正交搜索极化优化方法并进行了详细的讨论.该方法首先沿着一条特殊的基线进行局部优化就基本接近全局最优点,接着进行两个正交方向上的零导数搜索,而且搜索过程中每一步都只需简单地利用前一步局部最优解的结果.经过大量试验,给出了参数范围.结果表明ZDOS方法是有效的,基本上只需几步计算后就找到了全局最优点.     

一种新的2CPFSK信号极化合成方法

针对低信噪比下连续相位调制信号的极化合成,提出了一种基于多符号检测技术的极 化合成新方法。通过把解调和极化合成作为一个整体进行处理,在基带上完成了通常在中频 上实现的极化合成过程,避免了连续相位调制信号在低信噪比下载波相位跟踪困难的问题。 仿真结果表明,该方法的合成效果与理论值之间的差距小于0.3 dB。     

基于支持向量机的极化SAR图像分类

与传统最大似然（ML）分类器相比，支持向量机（SVM）在小训练样本时仍具有良好的分类性能，目前已广泛应用于多个领域。该文在极化SAR特征提取的基础上，将SVM应用于极化SAR图像分类，分析了分类器参数对分类性能的影响。利用NASA／JPL实验室AIRSAR系统的L波段旧金山全极化SAR数据比较了SVM和ML的分类性能，并进一步给出了基于SVM的国内某地区双极化SAR图像分类结果。     

一种用于CDMA系统的正交序列调制方法

在宽带移动通信系统中，经常考虑采用通过ＦＦＴ实现的多载波调制，如ＯＦＤＭ。本文提出了一种利用ＦＨＴ实现的ＣＤＭＡ系统的正交序列调制方案。其基本思想为利用Ｗａｌｓｈ函数作为载波，将Ｗａｌｓｈ函数分组，从每组中选出一些作为载波，这样不同的载波组合方式本身将包含用户信息。这种方法实现简单，可提高传输效率，并容易与ＣＤＭＡ相结合，能有效地抑制多径干扰。仿真结果表明，该方案在多径衰落信道中能得到很好的性能。     

一种线性化的全双工MIMO收发器设计

针对全双工MIMO收发器发射通道非线性以及接收通道存在强烈自干扰的问题,该文提出一种使发射通道线性化并通过射频多抽头重建与数字重建消除自干扰的具有较低硬件成本与软件复杂度的设计方案：(1)基于改进的串扰消除和数字预失真(CTC-DPD)算法并复用反馈通道进行去耦合和数字预失真使发射通道线性化、等增益;(2)在接收通道加入可调衰减器并用多维梯度下降法基于接收的残留自干扰功率最小原则调整抽头参数;(3)基于频域信道估计进行数字自干扰重建。实现的20 MHz带宽LTE全双工22 MIMO通信样机,发射通道经过线性化后带内更平坦,而带外噪声抑制了约30 dB。射频和数字消除一轮调整共耗时约0.17 ms,总消除能力约75 dB。16QAM映射时全双工双向数据速率总和220 Mbps,相对单向时的110 Mbps实现了频谱效率的翻倍。通信样机证明了该方案的可行性。     

一种基于支持向量机的数字调制识别方法

自动调制方式识别是非协作通信研究中的重要内容.本文提出了一种基于支持向量机的数字通信信号调制方式识别方法.从信号的瞬时幅度,相位,频率和频谱等特性中提取了7个特征参数,用于训练支持向量机.与已有算法相比,本文算法结构简单、计算量小,同时考虑了符号成型的影响.仿真结果证明,当信噪比大于10dB时,算法的识别率可以达到95%以上.     

消除数字闭环光纤陀螺串扰的多态调制方法

针对数字闭环光纤陀螺中由串扰引起的死区问题,本文提出了一种新的在不同调制深度下消除串扰的多态调制方法。根据数字闭环光纤陀螺调制解调的原理,建立了调制序列与解调序列的相关函数,当该相关函数为零时,可以获得多态调制序列中φm与2π-φm的比例关系,从而获得了不同调制深度下消除串扰的多态调制方案。对不同调制深度下构造的多态调制方案进行实验测试,结果表明,本文提出的数字闭环光纤陀螺多态调制方案能消除由串扰引起的死区问题。     

基于多相正交序列的扩频通信系统的调制解调方法的研究

针对基于多相正交序列的CDMA通信系统中尚未解决的调制解调问题,文章提出一种调制解调方法.并对基于此调制解调方法的CDMA通信系统的性能进行了分析.经分析可知,采用此种调制解调方法的多相正交序列CDMA通信系统具有优良的相关接收性能和抗多址干扰性能,且比理论上多相正交序列的相关接收性能和抗多址干扰性能有一定程度的提高.     

Two-states method for polarization dependent loss measurement

We report a two-states method for measuring polarization dependent loss (PDL) in an optical fiber system. Based on the property that the Mueller matrix governing the transmission property of any linear, time-invariant optical system with birefringence and PDL satisfies Lorentz transformation, we prove that PDL depends on the first column of the Mueller matrix. Hence only two orthogonal input polarization states are required to explicitly determine PDL. Experiment results show the agreement of our method with previously reported methods.     

基于偏振相关损耗测量磁场的高精度方法

为提高测量精度,提出了一种利用光纤光栅测量磁场的方法.依据磁场与光纤光栅偏振相关损耗成正比的理论,运用正交共轭反射镜来消除线性双折射,以Muller矩阵为基本方法,设计磁场测量原理图.数值仿真表明,通过正交共轭反射镜可以大幅度减少测量过程中的线性双折射,从而提高磁场的测量精度.     

Polarization dependent loss vector measurement in a system with polarization mode dispersion

A polarization dependent loss (PDL) vector equation of motion in Stokes space was derived in a system interacting with polarization mode dispersion (PMD). A new PDL measurement method based on the PDL vector equation was proposed and validated by numerical simulation and experiment.     

Measurement of polarization mode dispersion in systems having polarization dependent loss or gain

The principal states of polarization and their propagation characteristics are analyzed for both unitary and nonunitary optical systems in terms of the complex plane representation of polarization. A new method for the estimation of the polarization mode dispersion of the system is proposed together with experimental and simulation results.     

Polarization dependent loss and temperature fluctuations effect on degree of orthogonality in polarization multiplexed arrayed waveguide grating based distribution networks

We analyze the effect of arrayed-waveguide grating (AWG) polarization dependent loss (PDL) on the orthogonality between polarization multiplexed channels in a cascaded AWG-based access network topology. For a single AWG, with 0.5-dB PDL, we find an experimental degradation in polarization multiplexing orthogonality to be a maximum of 0.9/spl deg/, in good agreement with theory. In addition, experimental, and numerically simulated maps of orthogonality degradation versus input states of polarization (SOP) are investigated and found to agree well. Consequently, we analyze the effect of cascaded AWGs and again find that the experimental result of maximum 2.9/spl deg/ degradation in polarization multiplexing orthogonality closely matches theoretical predictions. Thermal variations are also found to have similar effects for all SOPs, with a measured degradation in orthogonality of up to 2.5/spl deg/ for a temperature range between 20/spl deg/C and 55/spl deg/C. Overall, this indicates the robustness of polarization multiplexing, making it applicable for appropriate deployment in bandwidth/user-enhanced access networks based on cascaded AWGs.     

Polarization mode dispersion and polarization dependent loss for apulse in single-mode fibers

Polarization mode dispersion (PMD) and polarization dependent loss (PDL) for a pulse in optical fibers are calculated with a model of two concatenated fibers. Each of the two fibers has both elliptical birefringence and PDL. The results show that the PMD and PDL for a short pulse can be very different from those for a narrow-band pulse in optical fibers. Two anomalous results are reported: (1) the effective PDL for a pulse can be smaller than the PDL difference of the two fibers and (2) the effective PMD for a pulse can be either larger than the sum of the differential group delays (DGDs) of the two fibers or less than the DGD difference of the two fibers, depending on the input pulsewidth. The pulse distortions when the pulses are launched into the two principal states of polarization (PSPs) are discussed     

基于Stokes参量法测量矢量光束偏振态的方法

矢量光束的偏振态检测是矢量光束研究的关键技术。论文研究了基于Stokes参量法测量矢量光束偏振态的方法,介绍了该方法的基本原理和实现过程。基于猫眼腔激光器和马赫-曾德干涉仪生成了4种不同偏振态分布的轴对称线偏振矢量光束,并用Stokes参量法计算了生成光束的四个Stokes参量,以及光束每个像素点上的椭圆取向角和椭圆率角,得到了生成光束的偏振纯度。实验结果证明了Stokes参量法可有效实现矢量光束的偏振态检测。     

Repolarization of polarization-scrambled optical signals due to polarization dependent loss

We calculate the distribution function of the degree of polarization of an initially polarization scrambled signal propagating long distances in an optical fiber. We show that a significant repolarization can occur for modern-day parameters. We estimate how far the polarization dependent loss must be reduced before repolarization becomes negligible.     

熔锥型宽带耦合器偏振相关损耗研究

研究了熔锥型宽带耦合嚣的偏振相关损耗(PDL),发现构成宽带耦合嚣的两熔融光纤结构上的不对称是导致其PDL不能为0的根本原因。通过对宽带耦合器结构的优化设计,报道了目前PDL最低的宽带耦合器：1310nm窗口PDL≤0．05dB;1550nm窗口PDL≤0．07dB。     

Probability density function of polarization dependent loss (PDL)in optical transmission system composed of passive devices andconnecting fibers

This paper presents a probability density function formula for predicting the polarization dependent loss (PDL) in an optical transmission system composed of passive devices and connecting fibers. A new calculation technique, which enables the probability density function formula to be obtained theoretically, is used instead of the most complicated part of the Muller-matrix or Jones-matrix calculations, which has been thought to be necessary for analyzing PDL. This technique involves calculation of the transmission coefficients of the transmission system and its devices from their PDLs. In the theoretical development, the central limit theorem is used as the sole approximation. A Monte Carlo numerical simulation was done to verify the validity of the analytical theory. Very good agreement between simulation and analytical theory is obtained when the number of devices having PDL is four or more. An experiment also demonstrated the validity of the analytical theory. The theory can also explain some phenomena that occur in systems composed of optical amplifiers, even though it had originally been developed to explain PDL-related phenomena in systems composed of passive devices only