Characterization of the Dynamic Absorption of Electroabsorption Modulators With Application to OTDM Demultiplexing

In this paper, a technique for characterizing the dynamic absorption of electroabsorption modulators (EAMs) under high-frequency sinusoidal modulation is described. By using an optical sampling oscilloscope (OSO), the nonlinear response of a modulator to 10- and 40-GHz modulation is accurately measured. The results for the dynamic absorption are used in a measurement-based model to calculate optical gating windows for the demultiplexing of a 160-Gb/s optical time-division multiplexed (OTDM) signal to its 10- and 40-Gb/s tributary signals. Good agreement is achieved between the calculated and measured gating windows.      

利用半导体光放大器环路镜实现4×2.5GHzOTDM解复用

报道了利用半导体光放大器环路镜对４×２．５ＧＨｚ光时分复用（ＯＴＤＭ）进行全光解复用的实验，实验结果表明用该方法解复用可得到具有很好消光比的解复用信号。     

4×10 GHz的OTDM系统时钟提取及解复用实验研究

对4×10 GHz光时分复用(OTDM)系统中,基于LiNbO3调制器的注入光电混合振荡器的时钟提取方法进行了实验验证,提取的时钟抖动小于0.5 ps.从实验上分析了入射光功率对时钟信号的影响.同时利用提取的时钟实现了基于电吸收调制(EAM)晶体的各个信道的解复用,解复用信号基本无邻道串扰.     

一种基于TOAD的OTDM光网络自同步方案

自同步在OTDM(光时分复用)分组网络中占有十分重要的地位，为此提出了一种简单的基于太赫兹光学非对称解复用器(TOAD)的自同步方案，给出了理论模型并进行了数值仿真，最后分析了SOA(半导体光放大器)饱和能量对该方案性能的影响。     

Analysis of Ultrafast All-Optical OTDM Demultiplexing Based on Cascaded Wavelength Conversion in PPLN Waveguides

Ultrafast all-optical optical time-division multiplexing demultiplexing based on the cascaded second-harmonic generation and difference-frequency generation wavelength conversion in quasi-phase-matched periodically poled lithium niobate waveguides are studied theoretically. For a typical 160- to 10-Gb/s demultiplexing process, conversion efficiency, pulse shape, time delay, phase variation, and crosstalk are investigated in two different arrangements of the 160-Gb/s signals, and both the wavelength conversion and pulse reshaping can be realized     

基于BICM的高效编码协作方案及性能分析

 提出一种基于比特交织编码调制(BICM)的高效编码协作(CC)方案,该方案中协作用户编码比特分为两帧,每一帧都通过BICM调制发送,通过结合比特交织器满足高阶调制星座符号的不同比特经历的衰落独立。一方面,论文分析了该协作方案在不同信道下的成对错误概率,并进一步推导了错误比特概率上界。理论分析以及仿真结果都表明：准静态衰落信道下,基于BICM的高谱效率编码协作方案仍然可以获得完全分集;而快衰落信道下,编码协作没有分集。另一方面,论文针对提出CC方案中映射方式以及交织器的设计进行研究,得出GRAY映射仍然是协作用户采用的最佳映射,且两帧的交织器不同更利于提高性能。     

Zero-Voltage-Switching PWM Hybrid Full-Bridge Three-Level Converter With Secondary-Voltage Clamping Scheme

A hybrid full-bridge (H-FB) three-level (TL) converter can realize zero-voltage-switching for switches with the use of resonant inductance (including the leakage inductance of the transformer) and intrinsic capacitors of the switches. As it can operate in three-level and two-level (2L) modes, the secondary rectified voltage is always close to the output voltage over the input-voltage range; thus, the output filter requirement is significantly less. Meanwhile, the voltage stress of the rectifier diodes can also be reduced. Therefore, the H-FB TL converter is very attractive for wide input-voltage-range applications. However, there is a serious voltage oscillation across the rectifier diodes caused by reverse recovery like the Buck-derived converters. In this paper, two clamping diodes are introduced to the H-FB TL converter to eliminate the voltage oscillation across the rectifier diodes. The arrangement of the positions of the resonant inductance and the transformer is discussed. The operation principle of the proposed converter is analyzed in details. A 1.2-kW prototype was built and tested in the laboratory to verify the operation of the proposed converter.     

A Baseband Hybrid Digital Transmission Scheme

A baseband hybrid digital transmission scheme is studied, and it is shown that the low- and high-frequency cutoffs in analog repeaters extremely degrade signal waveforms. Solutions studied are a combination of dc-constrained coding and modification of amplitude-frequency characteristics for low-frequency distortion, and a combination of flat amplitude equalization and simple phase equalization for high-frequency distortion. It is shown that these solutions reduce waveform distortions by a factor of ten. A solution of the control problem for automatic gain control (AGC) is also presented.     

A New Hybrid Random PWM Scheme

This paper proposes a new hybrid random pulsewidth modulation (PWM) scheme based on a TMS320LF2407 DSP, in order to disperse the acoustic switching noise spectra of an induction motor drive. The proposed random PWM pulses are produced through the logical comparison of a pseudorandom binary sequence (PRBS) bits with the PWM pulses corresponding to two random triangular carriers. For this reason, the PWM pulses of the proposed scheme possess the hybrid characteristics of the random pulse position PWM and the random carrier frequency PWM. In order to verify the validity of the proposed method, the simulations and experiments were conducted with a 1.5-kW three-phase induction motor under the 2.5-A load condition. The DSP generates the random numbers, the PRBS bits with a lead-lag random bit (8 bit) and the three-phase reference signals. Also, a frequency modulator MAX038 makes the randomized frequency triangular carrier (3 $pm$ 1 kHz). From the results, the proposed scheme shows good randomization effects of the voltage, current, and acoustic noise of the motor as compared with conventional scheme (3 kHz).      

Cassegrain Antenna With Hybrid Beam Steering Scheme for Mobile Satellite Communications

A hybrid antenna (HA) with a modified beam steering method is proposed. This antenna has a Cassegrain structure composed of two reflectors and a feeder. The parabolic-shaped main reflector is designed for high gain, while the subreflector is rotational and flat. The feeder is a phased array with arbitrary shaped aperture and 20 element antennas. The HA is capable of two-dimensional beam steering by means of two operations: rotation of the subreflector and phase control of the feed array. The subreflector is small in size and weight, so it can provide rapid beam scanning. Designed to be loaded in vehicles, the HA and can communicate with satellites on the move by tracking the beam control of the feed array. A prototype of the HA is fabricated with aluminum using a machining center operated by computerized numerical control. The prototype is operated at Ka-band for TX and K-band for RX with gains of 47 dBi and 44.4 dBi, respectively, at a steering angle of 0 $^{circ}$. The two-dimensional beam steering within $pm 2^{circ}$ with respect to 45$^{circ}$ elevation is realized by the subreflector and feed array. All radiation patterns in the beam steering zone meet ITU-R s.465-5 regulations.      

Demonstration of a Self-Synchronized Polyphase Sampling and Demultiplexing Scheme for Radio-Frequency Analog Signals

A novel self-synchronizing optoelectronics polyphase scheme for sampling and demultiplexing radio-frequency (RF) signals is demonstrated. One unique feature of this approach is that the optically sampled RF signal always remains in the electrical domain and thus eliminates the need for electrical-to-optical and back to electrical conversions. Furthermore, the simplicity and ease of construction of the scheme readily allows it to be scaled to obtain high sampling rates. As a proof of concept, a 100-MHz RF electrical signal sampled at the rate of 1.28 GS/s and then demultiplexed into four 320-MHz signals was experimentally demonstrated.     

Field Experiments With a Grooming Switch for OTDM Meshed Networking

Field experiments of 42.7/128.1 Gb/s wavelength-division multiplexed, optical time-division multiplexed (WDM-OTDM) transmultiplexing and all-optical dual-wavelength regeneration at the OTDM rate are presented in this paper. By using the asynchronous retiming scheme, we achieve error-free bufferless data grooming with time-slot interchange capability for OTDM meshed networking. We demonstrate excellent performance from the system, discuss scalability, applicability, and the potential reach of the asynchronous retiming scheme for transparent OTDM-domain interconnection.      

An SOA-MZI NRZ Wavelength Conversion Scheme With Enhanced 2R Regeneration Characteristics

We present a novel scheme for all-optical nonreturn-to-zero (NRZ) wavelength conversion with enhanced 2R regenerative characteristics. It employs a hybridly integrated semiconductor optical amplifier Mach-Zehnder interferometer using bidirectional data injection and an additional external continuous-wave signal for differentially biasing the interferometer arms, optimizing gain and phase conditions during the switching functionality. Experimental verification of its superior 2R regenerative capabilities are demonstrated for 10-Gb/s NRZ data signals.     

一种混合密码体制下的密钥管理方案

基于单一密码体制下的密钥管理系统都存在一些缺陷,不能完美地满足日益增长的应用需求。对于非对称密码体制的组合公钥技术,在安全性要求较高、相对封闭的应用环境下,有较好的实用特性。采用对称密码体制和公钥密码体制相结合的技术手段,设计出一个混合密码体制下的新型密钥管理系统,包括密钥管理模型、系统功能、密钥周期管理策略等,并对该系统的各项性能(安全性、高效性、灵和性、可扩展性)进行了详细的论述。     

一种多分辨率图像混合编码方案

本文提出一种基于小波变换与神经网络的多分辨率图像混合编码方案，利用小波分解对图像的多分辨率表示来消除图像空间域和频率域的相关性，由于小波图像相邻行之间的复杂关系难以用线性表示式来描述，使用多层神经网络（ＭＬＮＮ）来确定这种未知关系。实验证明，神经网络非线性预测器性能优于线性预测器，对非线性预测后的差值图像用自组织特征映射（ＳＯＦＭ）码书进行矢量量化（ＶＱ）编码，编码图像主观质量好，压缩比高，算法简     

一种新型集成解复用接收器的设计

提出了一种基于楔形F-P腔滤波器的并行探测集成解复用接收器.利用转移矩阵方法对这种新型并行解复用接收器进行了理论分析,给出了并行解复用接收器并行探测四个波长的具体设计实例.最后,使用数值模拟的方法对这种新型并行探测集成解复用接收器的解复用性能和串扰特性进行了计算,并作了分析.     

Enhanced P3HT OTFT Transport Performance Using Double Gate Modulation Scheme

Electrical properties of single-gated (bottom-gated or top-gated) and double-gated (DG) organic thin-film transistors (OTFTs) are systematically investigated in terms of threshold voltage $(V_{rm th})$, subthreshold slope, and $I_{{rm ON}/{rm OFF}}$ . We found that the device structure has significant impacts on the aforementioned electrical properties and the operation modes in a poly-3-hexyl thiophene DG OTFT. An empirical electrostatic potential model is employed to describe well $V_{rm th}$ behaviors of DG OTFTs in different modulation schemes. In addition, selective active-area coating in OTFTs is realized using an inkjet printing process, and consequently, parasitic leakage is much suppressed.      

一种基于SIC-CDM的低复杂度混合波束赋形方案

为了平衡毫米波大规模多输入多输出系统的性能和硬件开销,降低系统功耗,以频谱效率为优化目标,在部分连接结构下提出了一种收发端联合设计的低复杂度混合波束赋形方案。首先,基于连续干扰消除将原始优化问题转化为多个子阵的速率优化问题;然后,利用坐标下降法完成模拟波束赋形矩阵设计;最后,引入等效信道矩阵大幅降低矩阵维度,再对其进行奇异值分解获得数字波束赋形矩阵。仿真结果表明,与其他算法相比,所提算法在系统功耗降低的同时保持了较优的性能,且性能逼近部分连接结构的最优方案。     

一种低功耗的混合谐振时钟分布机制

提出了一种低功耗的混合谐振时钟分布机制,通过改进的旋转行波振荡器产生和分布方波形全局时钟信号,采用基于片上变压器的谐振电路产生局部谐振时钟信号.在SMIC 0.13μm CMOS工艺下,对目标频率为1 91GHz的混合时钟网络进行了设计和仿真,能够显著降低时钟系统功耗.     

CAP-DPIM可见光混合调制方案

针对可见光通信系统传输性能问题,文章提出了一种无载波幅度相位(CAP)调制与数字脉冲间隔调制(DPIM)结合的混合调制方案。该方案分别利用两者频谱效率和功率效率较高的特点,发送端在脉冲间隔调制的脉冲时隙加载直流偏置光CAP(DCO-CAP)信号,实现混合调制信号的并行生成,接收端通过门限检测和最大似然检测完成混合调制信号的串行解调。推导了室内可见光高斯信道下混合调制方案的误码率(BER)及误帧率(FER)解析表达式。此外,从频谱效率和FER两方面对比分析了该混合调制方案与传统DPIM及DCO-CAP方案的性能优劣。数值仿真结果表明:当频谱效率相同时,混合调制方案较单一调制有更高的可靠性。